8333396: Use StringBuilder internally for java.text.Format.* formatting

Reviewed-by: naoto, liach, jlu

src/java.base/share/classes/java/text/CharacterIteratorFieldDelegate.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -54,7 +54,7 @@ class CharacterIteratorFieldDelegate implements Format.FieldDelegate {
     }
 
     public void formatted(Format.Field attr, Object value, int start, int end,
-                          StringBuffer buffer) {
+                          Format.StringBuf buffer) {
         if (start != end) {
             if (start < size) {
                 // Adjust attributes of existing runs
@@ -93,7 +93,7 @@ class CharacterIteratorFieldDelegate implements Format.FieldDelegate {
     }
 
     public void formatted(int fieldID, Format.Field attr, Object value,
-                          int start, int end, StringBuffer buffer) {
+                          int start, int end, Format.StringBuf buffer) {
         formatted(attr, value, start, end, buffer);
     }
 

src/java.base/share/classes/java/text/ChoiceFormat.java

@@ -514,7 +514,13 @@ public class ChoiceFormat extends NumberFormat {
     @Override
     public StringBuffer format(long number, StringBuffer toAppendTo,
                                FieldPosition status) {
-        return format((double)number, toAppendTo, status);
+        return format((double) number, StringBufFactory.of(toAppendTo), status).asStringBuffer();
+    }
+
+    @Override
+    StringBuf format(long number, StringBuf toAppendTo,
+                     FieldPosition status) {
+        return format((double) number, toAppendTo, status);
     }
 
     /**
@@ -531,6 +537,12 @@ public class ChoiceFormat extends NumberFormat {
     @Override
     public StringBuffer format(double number, StringBuffer toAppendTo,
                                FieldPosition status) {
+        return format(number, StringBufFactory.of(toAppendTo), status).asStringBuffer();
+    }
+
+    @Override
+    StringBuf format(double number, StringBuf toAppendTo,
+                         FieldPosition status) {
         // find the number
         int i;
         for (i = 0; i < choiceLimits.length; ++i) {

src/java.base/share/classes/java/text/CompactNumberFormat.java

@@ -552,6 +552,35 @@ public final class CompactNumberFormat extends NumberFormat {
                 && ((BigInteger) number).bitLength() < 64)) {
             return format(((Number) number).longValue(), toAppendTo,
                     fieldPosition);
+        } else if (number instanceof BigDecimal) {
+            return format((BigDecimal) number, StringBufFactory.of(toAppendTo), fieldPosition).asStringBuffer();
+        } else if (number instanceof BigInteger) {
+            return format((BigInteger) number, StringBufFactory.of(toAppendTo), fieldPosition).asStringBuffer();
+        } else if (number instanceof Number) {
+            return format(((Number) number).doubleValue(), toAppendTo, fieldPosition);
+        } else {
+            throw new IllegalArgumentException("Cannot format "
+                    + number.getClass().getName() + " as a number");
+        }
+    }
+
+    @Override
+    StringBuf format(Object number,
+                     StringBuf toAppendTo,
+                     FieldPosition fieldPosition) {
+
+        if (number == null) {
+            throw new IllegalArgumentException("Cannot format null as a number");
+        }
+
+        if (number instanceof Long || number instanceof Integer
+                    || number instanceof Short || number instanceof Byte
+                    || number instanceof AtomicInteger
+                    || number instanceof AtomicLong
+                    || (number instanceof BigInteger
+                                && ((BigInteger) number).bitLength() < 64)) {
+            return format(((Number) number).longValue(), toAppendTo,
+                    fieldPosition);
         } else if (number instanceof BigDecimal) {
             return format((BigDecimal) number, toAppendTo, fieldPosition);
         } else if (number instanceof BigInteger) {
@@ -560,7 +589,7 @@ public final class CompactNumberFormat extends NumberFormat {
             return format(((Number) number).doubleValue(), toAppendTo, fieldPosition);
         } else {
             throw new IllegalArgumentException("Cannot format "
-                    + number.getClass().getName() + " as a number");
+                                                       + number.getClass().getName() + " as a number");
         }
     }
 
@@ -591,12 +620,21 @@ public final class CompactNumberFormat extends NumberFormat {
     public StringBuffer format(double number, StringBuffer result,
             FieldPosition fieldPosition) {
 
+        fieldPosition.setBeginIndex(0);
+        fieldPosition.setEndIndex(0);
+        return format(number, StringBufFactory.of(result), fieldPosition.getFieldDelegate()).asStringBuffer();
+    }
+
+    @Override
+    StringBuf format(double number, StringBuf result,
+                     FieldPosition fieldPosition) {
+
         fieldPosition.setBeginIndex(0);
         fieldPosition.setEndIndex(0);
         return format(number, result, fieldPosition.getFieldDelegate());
     }
 
-    private StringBuffer format(double number, StringBuffer result,
+    private StringBuf format(double number, StringBuf result,
             FieldDelegate delegate) {
 
         boolean nanOrInfinity = decimalFormat.handleNaN(number, result, delegate);
@@ -681,12 +719,21 @@ public final class CompactNumberFormat extends NumberFormat {
     public StringBuffer format(long number, StringBuffer result,
             FieldPosition fieldPosition) {
 
+        fieldPosition.setBeginIndex(0);
+        fieldPosition.setEndIndex(0);
+        return format(number, StringBufFactory.of(result), fieldPosition.getFieldDelegate()).asStringBuffer();
+    }
+
+    @Override
+    StringBuf format(long number, StringBuf result,
+                     FieldPosition fieldPosition) {
+
         fieldPosition.setBeginIndex(0);
         fieldPosition.setEndIndex(0);
         return format(number, result, fieldPosition.getFieldDelegate());
     }
 
-    private StringBuffer format(long number, StringBuffer result, FieldDelegate delegate) {
+    private StringBuf format(long number, StringBuf result, FieldDelegate delegate) {
         boolean isNegative = (number < 0);
         if (isNegative) {
             number = -number;
@@ -757,15 +804,15 @@ public final class CompactNumberFormat extends NumberFormat {
      *                         of the prefix and the suffix fields can be
      *                         obtained using {@link NumberFormat.Field#PREFIX}
      *                         and {@link NumberFormat.Field#SUFFIX} respectively.
-     * @return        the {@code StringBuffer} passed in as {@code result}
+     * @return        the {@code StringBuf} passed in as {@code result}
      * @throws        ArithmeticException if rounding is needed with rounding
      *                mode being set to {@code RoundingMode.UNNECESSARY}
      * @throws        NullPointerException if any of the given parameter
      *                is {@code null}
      * @see FieldPosition
      */
-    private StringBuffer format(BigDecimal number, StringBuffer result,
+    private StringBuf format(BigDecimal number, StringBuf result,
-            FieldPosition fieldPosition) {
+                             FieldPosition fieldPosition) {
 
         Objects.requireNonNull(number);
         fieldPosition.setBeginIndex(0);
@@ -773,7 +820,7 @@ public final class CompactNumberFormat extends NumberFormat {
         return format(number, result, fieldPosition.getFieldDelegate());
     }
 
-    private StringBuffer format(BigDecimal number, StringBuffer result,
+    private StringBuf format(BigDecimal number, StringBuf result,
             FieldDelegate delegate) {
 
         boolean isNegative = number.signum() == -1;
@@ -843,15 +890,15 @@ public final class CompactNumberFormat extends NumberFormat {
      *                         prefix and the suffix fields can be obtained
      *                         using {@link NumberFormat.Field#PREFIX} and
      *                         {@link NumberFormat.Field#SUFFIX} respectively.
-     * @return        the {@code StringBuffer} passed in as {@code result}
+     * @return        the {@code StringBuf} passed in as {@code result}
      * @throws        ArithmeticException if rounding is needed with rounding
      *                mode being set to {@code RoundingMode.UNNECESSARY}
      * @throws        NullPointerException if any of the given parameter
      *                is {@code null}
      * @see FieldPosition
      */
-    private StringBuffer format(BigInteger number, StringBuffer result,
+    private StringBuf format(BigInteger number, StringBuf result,
-            FieldPosition fieldPosition) {
+                             FieldPosition fieldPosition) {
 
         Objects.requireNonNull(number);
         fieldPosition.setBeginIndex(0);
@@ -859,7 +906,7 @@ public final class CompactNumberFormat extends NumberFormat {
         return format(number, result, fieldPosition.getFieldDelegate(), false);
     }
 
-    private StringBuffer format(BigInteger number, StringBuffer result,
+    private StringBuf format(BigInteger number, StringBuf result,
             FieldDelegate delegate, boolean formatLong) {
 
         boolean isNegative = number.signum() == -1;
@@ -936,7 +983,7 @@ public final class CompactNumberFormat extends NumberFormat {
      *                 {@code NumberFormat.Field.SIGN} and
      *                 {@code NumberFormat.Field.PREFIX} fields
      */
-    private void appendPrefix(StringBuffer result, String prefix,
+    private void appendPrefix(StringBuf result, String prefix,
             FieldDelegate delegate) {
         append(result, expandAffix(prefix), delegate,
                 getFieldPositions(prefix, NumberFormat.Field.PREFIX));
@@ -952,7 +999,7 @@ public final class CompactNumberFormat extends NumberFormat {
      *                 {@code NumberFormat.Field.SIGN} and
      *                 {@code NumberFormat.Field.SUFFIX} fields
      */
-    private void appendSuffix(StringBuffer result, String suffix,
+    private void appendSuffix(StringBuf result, String suffix,
             FieldDelegate delegate) {
         append(result, expandAffix(suffix), delegate,
                 getFieldPositions(suffix, NumberFormat.Field.SUFFIX));
@@ -968,7 +1015,7 @@ public final class CompactNumberFormat extends NumberFormat {
      * @param positions a list of {@code FieldPosition} in the given
      *                  string
      */
-    private void append(StringBuffer result, String string,
+    private void append(StringBuf result, String string,
             FieldDelegate delegate, List<FieldPosition> positions) {
         if (!string.isEmpty()) {
             int start = result.length();
@@ -1134,7 +1181,7 @@ public final class CompactNumberFormat extends NumberFormat {
     public AttributedCharacterIterator formatToCharacterIterator(Object obj) {
         CharacterIteratorFieldDelegate delegate
                 = new CharacterIteratorFieldDelegate();
-        StringBuffer sb = new StringBuffer();
+        StringBuf sb = StringBufFactory.of();
 
         if (obj instanceof Double || obj instanceof Float) {
             format(((Number) obj).doubleValue(), sb, delegate);

src/java.base/share/classes/java/text/DateFormat.java

@@ -346,6 +346,19 @@ public abstract class DateFormat extends Format {
             throw new IllegalArgumentException("Cannot format given Object as a Date");
     }
 
+    @Override
+    final StringBuf format(Object obj, StringBuf toAppendTo,
+                           FieldPosition fieldPosition) {
+        if (obj instanceof Date) {
+            return format((Date) obj, toAppendTo, fieldPosition);
+        } else if (obj instanceof Number) {
+            return format(new Date(((Number) obj).longValue()),
+                    toAppendTo, fieldPosition);
+        } else {
+            throw new IllegalArgumentException("Cannot format given Object as a Date");
+        }
+    }
+
     /**
      * Formats a {@link Date} into a date-time string. The formatted
      * string is appended to the given {@code StringBuffer}.
@@ -371,6 +384,11 @@ public abstract class DateFormat extends Format {
     public abstract StringBuffer format(Date date, StringBuffer toAppendTo,
                                         FieldPosition fieldPosition);
 
+    StringBuf format(Date date, StringBuf toAppendTo,
+                     FieldPosition fieldPosition) {
+        throw new UnsupportedOperationException("Subclasses should override this method");
+    }
+
     /**
      * Formats a {@link Date} into a date-time string.
      *
@@ -379,8 +397,14 @@ public abstract class DateFormat extends Format {
      */
     public final String format(Date date)
     {
-        return format(date, new StringBuffer(),
+        if ("java.text".equals(getClass().getPackageName())
-                      DontCareFieldPosition.INSTANCE).toString();
+                    && "java.text".equals(numberFormat.getClass().getPackageName())) {
+            return format(date, StringBufFactory.of(),
+                    DontCareFieldPosition.INSTANCE).toString();
+        } else {
+            return format(date, new StringBuffer(),
+                    DontCareFieldPosition.INSTANCE).toString();
+        }
     }
 
     /**

src/java.base/share/classes/java/text/DecimalFormat.java

@@ -556,9 +556,9 @@ public class DecimalFormat extends NumberFormat {
                     ((BigInteger)number).bitLength () < 64)) {
             return format(((Number)number).longValue(), toAppendTo, pos);
         } else if (number instanceof BigDecimal) {
-            return format((BigDecimal)number, toAppendTo, pos);
+            return format((BigDecimal)number, StringBufFactory.of(toAppendTo), pos).asStringBuffer();
         } else if (number instanceof BigInteger) {
-            return format((BigInteger)number, toAppendTo, pos);
+            return format((BigInteger)number, StringBufFactory.of(toAppendTo), pos).asStringBuffer();
         } else if (number instanceof Number) {
             return format(((Number)number).doubleValue(), toAppendTo, pos);
         } else {
@@ -566,6 +566,28 @@ public class DecimalFormat extends NumberFormat {
         }
     }
 
+    @Override
+    final StringBuf format(Object number,
+                           StringBuf toAppendTo,
+                           FieldPosition pos) {
+        if (number instanceof Long || number instanceof Integer ||
+                    number instanceof Short || number instanceof Byte ||
+                    number instanceof AtomicInteger ||
+                    number instanceof AtomicLong ||
+                    (number instanceof BigInteger &&
+                             ((BigInteger) number).bitLength() < 64)) {
+            return format(((Number) number).longValue(), toAppendTo, pos);
+        } else if (number instanceof BigDecimal) {
+            return format((BigDecimal) number, toAppendTo, pos);
+        } else if (number instanceof BigInteger) {
+            return format((BigInteger) number, toAppendTo, pos);
+        } else if (number instanceof Number) {
+            return format(((Number) number).doubleValue(), toAppendTo, pos);
+        } else {
+            throw new IllegalArgumentException("Cannot format given Object as a Number");
+        }
+    }
+
     /**
      * Formats a double to produce a string.
      * @param number    The double to format
@@ -588,6 +610,12 @@ public class DecimalFormat extends NumberFormat {
     @Override
     public StringBuffer format(double number, StringBuffer result,
                                FieldPosition fieldPosition) {
+        return format(number, StringBufFactory.of(result), fieldPosition).asStringBuffer();
+    }
+
+    @Override
+    StringBuf format(double number, StringBuf result,
+                     FieldPosition fieldPosition) {
         // If fieldPosition is a DontCareFieldPosition instance we can
         // try to go to fast-path code.
         boolean tryFastPath = false;
@@ -619,8 +647,8 @@ public class DecimalFormat extends NumberFormat {
      *                  mode being set to RoundingMode.UNNECESSARY
      * @return The formatted number string
      */
-    StringBuffer format(double number, StringBuffer result,
+    StringBuf format(double number, StringBuf result,
-                                FieldDelegate delegate) {
+                     FieldDelegate delegate) {
 
         boolean nanOrInfinity = handleNaN(number, result, delegate);
         if (nanOrInfinity) {
@@ -666,7 +694,7 @@ public class DecimalFormat extends NumberFormat {
      * @param delegate notified of locations of sub fields
      * @return true, if number is a NaN; false otherwise
      */
-    boolean handleNaN(double number, StringBuffer result,
+    boolean handleNaN(double number, StringBuf result,
             FieldDelegate delegate) {
         if (Double.isNaN(number)
                 || (Double.isInfinite(number) && multiplier == 0)) {
@@ -691,7 +719,7 @@ public class DecimalFormat extends NumberFormat {
      * @return true, if number is a {@code Double.NEGATIVE_INFINITY} or
      *         {@code Double.POSITIVE_INFINITY}; false otherwise
      */
-    boolean handleInfinity(double number, StringBuffer result,
+    boolean handleInfinity(double number, StringBuf result,
             FieldDelegate delegate, boolean isNegative) {
         if (Double.isInfinite(number)) {
             if (isNegative) {
@@ -720,7 +748,7 @@ public class DecimalFormat extends NumberFormat {
         return false;
     }
 
-    StringBuffer doubleSubformat(double number, StringBuffer result,
+    StringBuf doubleSubformat(double number, StringBuf result,
             FieldDelegate delegate, boolean isNegative) {
         synchronized (digitList) {
             int maxIntDigits = super.getMaximumIntegerDigits();
@@ -761,6 +789,14 @@ public class DecimalFormat extends NumberFormat {
         fieldPosition.setBeginIndex(0);
         fieldPosition.setEndIndex(0);
 
+        return format(number, StringBufFactory.of(result), fieldPosition.getFieldDelegate()).asStringBuffer();
+    }
+
+    StringBuf format(long number, StringBuf result,
+                     FieldPosition fieldPosition) {
+        fieldPosition.setBeginIndex(0);
+        fieldPosition.setEndIndex(0);
+
         return format(number, result, fieldPosition.getFieldDelegate());
     }
 
@@ -774,8 +810,8 @@ public class DecimalFormat extends NumberFormat {
      *                   mode being set to RoundingMode.UNNECESSARY
      * @see java.text.FieldPosition
      */
-    StringBuffer format(long number, StringBuffer result,
+    StringBuf format(long number, StringBuf result,
-                               FieldDelegate delegate) {
+                     FieldDelegate delegate) {
         boolean isNegative = (number < 0);
         if (isNegative) {
             number = -number;
@@ -849,8 +885,8 @@ public class DecimalFormat extends NumberFormat {
      *                   mode being set to RoundingMode.UNNECESSARY
      * @see java.text.FieldPosition
      */
-    private StringBuffer format(BigDecimal number, StringBuffer result,
+    private StringBuf format(BigDecimal number, StringBuf result,
-                                FieldPosition fieldPosition) {
+                             FieldPosition fieldPosition) {
         fieldPosition.setBeginIndex(0);
         fieldPosition.setEndIndex(0);
         return format(number, result, fieldPosition.getFieldDelegate());
@@ -865,8 +901,8 @@ public class DecimalFormat extends NumberFormat {
      *                   mode being set to RoundingMode.UNNECESSARY
      * @return The formatted number string
      */
-    StringBuffer format(BigDecimal number, StringBuffer result,
+    StringBuf format(BigDecimal number, StringBuf result,
-                                FieldDelegate delegate) {
+                     FieldDelegate delegate) {
         if (multiplier != 1) {
             number = number.multiply(getBigDecimalMultiplier());
         }
@@ -908,8 +944,8 @@ public class DecimalFormat extends NumberFormat {
      *                   mode being set to RoundingMode.UNNECESSARY
      * @see java.text.FieldPosition
      */
-    private StringBuffer format(BigInteger number, StringBuffer result,
+    private StringBuf format(BigInteger number, StringBuf result,
-                               FieldPosition fieldPosition) {
+                             FieldPosition fieldPosition) {
         fieldPosition.setBeginIndex(0);
         fieldPosition.setEndIndex(0);
 
@@ -926,8 +962,8 @@ public class DecimalFormat extends NumberFormat {
      *                   mode being set to RoundingMode.UNNECESSARY
      * @see java.text.FieldPosition
      */
-    StringBuffer format(BigInteger number, StringBuffer result,
+    StringBuf format(BigInteger number, StringBuf result,
-                               FieldDelegate delegate, boolean formatLong) {
+                     FieldDelegate delegate, boolean formatLong) {
         if (multiplier != 1) {
             number = number.multiply(getBigIntegerMultiplier());
         }
@@ -986,7 +1022,7 @@ public class DecimalFormat extends NumberFormat {
     public AttributedCharacterIterator formatToCharacterIterator(Object obj) {
         CharacterIteratorFieldDelegate delegate =
                          new CharacterIteratorFieldDelegate();
-        StringBuffer sb = new StringBuffer();
+        StringBuf sb = StringBufFactory.of();
 
         if (obj instanceof Double || obj instanceof Float) {
             format(((Number)obj).doubleValue(), sb, delegate);
@@ -1779,7 +1815,7 @@ public class DecimalFormat extends NumberFormat {
      * Complete the formatting of a finite number.  On entry, the digitList must
      * be filled in with the correct digits.
      */
-    private StringBuffer subformat(StringBuffer result, FieldDelegate delegate,
+    private StringBuf subformat(StringBuf result, FieldDelegate delegate,
             boolean isNegative, boolean isInteger,
             int maxIntDigits, int minIntDigits,
             int maxFraDigits, int minFraDigits) {
@@ -1821,7 +1857,7 @@ public class DecimalFormat extends NumberFormat {
      * @param maxFraDigits maximum fraction digits
      * @param minFraDigits minimum fraction digits
      */
-    void subformatNumber(StringBuffer result, FieldDelegate delegate,
+    void subformatNumber(StringBuf result, FieldDelegate delegate,
             boolean isNegative, boolean isInteger,
             int maxIntDigits, int minIntDigits,
             int maxFraDigits, int minFraDigits) {
@@ -2108,7 +2144,7 @@ public class DecimalFormat extends NumberFormat {
      * <p>
      * This is used by {@code subformat} to add the prefix/suffix.
      */
-    private void append(StringBuffer result, String string,
+    private void append(StringBuf result, String string,
                         FieldDelegate delegate,
                         FieldPosition[] positions,
                         Format.Field signAttribute) {

src/java.base/share/classes/java/text/DontCareFieldPosition.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -36,10 +36,10 @@ class DontCareFieldPosition extends FieldPosition {
 
     private final Format.FieldDelegate noDelegate = new Format.FieldDelegate() {
         public void formatted(Format.Field attr, Object value, int start,
-                              int end, StringBuffer buffer) {
+                              int end, Format.StringBuf buffer) {
         }
         public void formatted(int fieldID, Format.Field attr, Object value,
-                              int start, int end, StringBuffer buffer) {
+                              int start, int end, Format.StringBuf buffer) {
         }
     };
 

src/java.base/share/classes/java/text/FieldPosition.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1996, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -290,7 +290,7 @@ public class FieldPosition {
         private boolean encounteredField;
 
         public void formatted(Format.Field attr, Object value, int start,
-                              int end, StringBuffer buffer) {
+                              int end, Format.StringBuf buffer) {
             if (!encounteredField && matchesField(attr)) {
                 setBeginIndex(start);
                 setEndIndex(end);
@@ -299,7 +299,7 @@ public class FieldPosition {
         }
 
         public void formatted(int fieldID, Format.Field attr, Object value,
-                              int start, int end, StringBuffer buffer) {
+                              int start, int end, Format.StringBuf buffer) {
             if (!encounteredField && matchesField(attr, fieldID)) {
                 setBeginIndex(start);
                 setEndIndex(end);

src/java.base/share/classes/java/text/Format.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1996, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -148,7 +148,8 @@ public abstract class Format implements Serializable, Cloneable {
     }
 
     /**
-     * Formats an object to produce a string. This is equivalent to
+     * Formats an object to produce a string.
+     * This method returns a string that would be equal to the string returned by
      * <blockquote>
      * {@link #format(Object, StringBuffer, FieldPosition) format}<code>(obj,
      *         new StringBuffer(), new FieldPosition(0)).toString();</code>
@@ -160,7 +161,11 @@ public abstract class Format implements Serializable, Cloneable {
      *            object
      */
     public final String format (Object obj) {
-        return format(obj, new StringBuffer(), new FieldPosition(0)).toString();
+        if ("java.text".equals(getClass().getPackageName())) {
+            return format(obj, StringBufFactory.of(), new FieldPosition(0)).toString();
+        } else {
+            return format(obj, new StringBuffer(), new FieldPosition(0)).toString();
+        }
     }
 
     /**
@@ -185,6 +190,12 @@ public abstract class Format implements Serializable, Cloneable {
                     StringBuffer toAppendTo,
                     FieldPosition pos);
 
+    StringBuf format(Object obj,
+                     StringBuf toAppendTo,
+                     FieldPosition pos) {
+        throw new UnsupportedOperationException("Subclasses should override this method");
+    }
+
     /**
      * Formats an Object producing an {@code AttributedCharacterIterator}.
      * You can use the returned {@code AttributedCharacterIterator}
@@ -394,7 +405,7 @@ public abstract class Format implements Serializable, Cloneable {
          *        NOT modify it.
          */
         public void formatted(Format.Field attr, Object value, int start,
-                              int end, StringBuffer buffer);
+                              int end, StringBuf buffer);
 
         /**
          * Notified when a particular region of the String is formatted.
@@ -408,6 +419,38 @@ public abstract class Format implements Serializable, Cloneable {
          *        NOT modify it.
          */
         public void formatted(int fieldID, Format.Field attr, Object value,
-                              int start, int end, StringBuffer buffer);
+                              int start, int end, StringBuf buffer);
+    }
+
+    /**
+     * StringBuf is the minimal common interface of {@code StringBuffer} and {@code StringBuilder}.
+     * It is used by the various {@code Format} implementations as the internal string buffer.
+     */
+    sealed interface StringBuf
+            permits StringBufFactory.StringBufferImpl, StringBufFactory.StringBuilderImpl {
+
+        int length();
+
+        String substring(int start, int end);
+
+        String substring(int start);
+
+        StringBuf append(char c);
+
+        StringBuf append(String str);
+
+        StringBuf append(int i);
+
+        StringBuf append(char[] str, int offset, int len);
+
+        StringBuf append(CharSequence s, int start, int end);
+
+        StringBuf append(StringBuffer sb);
+
+        boolean isProxyStringBuilder();
+
+        StringBuffer asStringBuffer();
+
+        StringBuilder asStringBuilder();
     }
 }

src/java.base/share/classes/java/text/ListFormat.java

@@ -356,7 +356,7 @@ public final class ListFormat extends Format {
     public String format(List<String> input) {
         Objects.requireNonNull(input);
 
-        return format(input, new StringBuffer(),
+        return format(input, StringBufFactory.of(),
                 DontCareFieldPosition.INSTANCE).toString();
     }
 
@@ -381,6 +381,18 @@ public final class ListFormat extends Format {
         Objects.requireNonNull(obj);
         Objects.requireNonNull(toAppendTo);
 
+        return format(obj, StringBufFactory.of(toAppendTo)).asStringBuffer();
+    }
+
+    @Override
+    StringBuf format(Object obj, StringBuf toAppendTo, FieldPosition pos) {
+        Objects.requireNonNull(obj);
+        Objects.requireNonNull(toAppendTo);
+
+        return format(obj, toAppendTo);
+    }
+
+    private StringBuf format(Object obj, StringBuf toAppendTo) {
         if (obj instanceof Object[] objs) {
             return generateMessageFormat(objs).format(objs, toAppendTo, DontCareFieldPosition.INSTANCE);
         } else if (obj instanceof List<?> objs) {

src/java.base/share/classes/java/text/MessageFormat.java

@@ -1027,12 +1027,13 @@ public class MessageFormat extends Format {
     public final StringBuffer format(Object[] arguments, StringBuffer result,
                                      FieldPosition pos)
     {
-        return subformat(arguments, result, pos, null);
+        return subformat(arguments, StringBufFactory.of(result), pos, null).asStringBuffer();
     }
 
     /**
      * Creates a MessageFormat with the given pattern and uses it
-     * to format the given arguments. This is equivalent to
+     * to format the given arguments.
+     * This method returns a string that would be equal to the string returned by
      * <blockquote>
      *     <code>(new {@link #MessageFormat(String) MessageFormat}(pattern)).{@link #format(java.lang.Object[], java.lang.StringBuffer, java.text.FieldPosition) format}(arguments, new StringBuffer(), null).toString()</code>
      * </blockquote>
@@ -1076,6 +1077,12 @@ public class MessageFormat extends Format {
     public final StringBuffer format(Object arguments, StringBuffer result,
                                      FieldPosition pos)
     {
+        return subformat((Object[]) arguments, StringBufFactory.of(result), pos, null).asStringBuffer();
+    }
+
+    @Override
+    final StringBuf format(Object arguments, StringBuf result,
+                           FieldPosition pos) {
         return subformat((Object[]) arguments, result, pos, null);
     }
 
@@ -1116,7 +1123,7 @@ public class MessageFormat extends Format {
      */
     public AttributedCharacterIterator formatToCharacterIterator(Object arguments) {
         Objects.requireNonNull(arguments, "arguments must not be null");
-        StringBuffer result = new StringBuffer();
+        StringBuf result = StringBufFactory.of();
         ArrayList<AttributedCharacterIterator> iterators = new ArrayList<>();
 
         subformat((Object[]) arguments, result, null, iterators);
@@ -1472,7 +1479,7 @@ public class MessageFormat extends Format {
      *            {@code arguments} array is not of the type
      *            expected by the format element(s) that use it.
      */
-    private StringBuffer subformat(Object[] arguments, StringBuffer result,
+    private StringBuf subformat(Object[] arguments, StringBuf result,
                                    FieldPosition fp, List<AttributedCharacterIterator> characterIterators) {
         // note: this implementation assumes a fast substring & index.
         // if this is not true, would be better to append chars one by one.
@@ -1582,9 +1589,9 @@ public class MessageFormat extends Format {
 
     /**
      * Convenience method to append all the characters in
-     * {@code iterator} to the StringBuffer {@code result}.
+     * {@code iterator} to the StringBuf {@code result}.
      */
-    private void append(StringBuffer result, CharacterIterator iterator) {
+    private void append(StringBuf result, CharacterIterator iterator) {
         if (iterator.first() != CharacterIterator.DONE) {
             char aChar;
 

src/java.base/share/classes/java/text/NumberFormat.java

@@ -315,6 +315,23 @@ public abstract class NumberFormat extends Format  {
         }
     }
 
+    @Override
+    StringBuf format(Object number,
+                     StringBuf toAppendTo,
+                     FieldPosition pos) {
+        if (number instanceof Long || number instanceof Integer ||
+                    number instanceof Short || number instanceof Byte ||
+                    number instanceof AtomicInteger || number instanceof AtomicLong ||
+                    (number instanceof BigInteger &&
+                             ((BigInteger) number).bitLength() < 64)) {
+            return format(((Number) number).longValue(), toAppendTo, pos);
+        } else if (number instanceof Number) {
+            return format(((Number) number).doubleValue(), toAppendTo, pos);
+        } else {
+            throw new IllegalArgumentException("Cannot format given Object as a Number");
+        }
+    }
+
     /**
      * {@inheritDoc Format}
      *
@@ -347,8 +364,13 @@ public abstract class NumberFormat extends Format  {
         if (result != null)
             return result;
 
-        return format(number, new StringBuffer(),
+        if ("java.text".equals(getClass().getPackageName())) {
-                      DontCareFieldPosition.INSTANCE).toString();
+            return format(number, StringBufFactory.of(),
+                    DontCareFieldPosition.INSTANCE).toString();
+        } else {
+            return format(number, new StringBuffer(),
+                    DontCareFieldPosition.INSTANCE).toString();
+        }
     }
 
     /*
@@ -367,8 +389,13 @@ public abstract class NumberFormat extends Format  {
      * @see java.text.Format#format
      */
     public final String format(long number) {
-        return format(number, new StringBuffer(),
+        if ("java.text".equals(getClass().getPackageName())) {
-                      DontCareFieldPosition.INSTANCE).toString();
+            return format(number, StringBufFactory.of(),
+                    DontCareFieldPosition.INSTANCE).toString();
+        } else {
+            return format(number, new StringBuffer(),
+                    DontCareFieldPosition.INSTANCE).toString();
+        }
     }
 
     /**
@@ -394,6 +421,12 @@ public abstract class NumberFormat extends Format  {
                                         StringBuffer toAppendTo,
                                         FieldPosition pos);
 
+    StringBuf format(double number,
+                     StringBuf toAppendTo,
+                     FieldPosition pos) {
+        throw new UnsupportedOperationException("Subclasses should override this method");
+    }
+
     /**
      * Specialization of format.
      *
@@ -417,6 +450,12 @@ public abstract class NumberFormat extends Format  {
                                         StringBuffer toAppendTo,
                                         FieldPosition pos);
 
+    StringBuf format(long number,
+                     StringBuf toAppendTo,
+                     FieldPosition pos) {
+        throw new UnsupportedOperationException("Subclasses should override this method");
+    }
+
     /**
      * Parses text from the beginning of the given string to produce a {@code Number}.
      * <p>

src/java.base/share/classes/java/text/SimpleDateFormat.java

@@ -968,11 +968,18 @@ public class SimpleDateFormat extends DateFormat {
                                FieldPosition pos)
     {
         pos.beginIndex = pos.endIndex = 0;
+        return format(date, StringBufFactory.of(toAppendTo), pos.getFieldDelegate()).asStringBuffer();
+    }
+
+    @Override
+    final StringBuf format(Date date, StringBuf toAppendTo,
+                           FieldPosition pos) {
+        pos.beginIndex = pos.endIndex = 0;
         return format(date, toAppendTo, pos.getFieldDelegate());
     }
 
     // Called from Format after creating a FieldDelegate
-    private StringBuffer format(Date date, StringBuffer toAppendTo,
+    private StringBuf format(Date date, StringBuf toAppendTo,
                                 FieldDelegate delegate) {
         // Convert input date to time field list
         calendar.setTime(date);
@@ -1024,7 +1031,7 @@ public class SimpleDateFormat extends DateFormat {
      */
     @Override
     public AttributedCharacterIterator formatToCharacterIterator(Object obj) {
-        StringBuffer sb = new StringBuffer();
+        StringBuf sb = StringBufFactory.of();
         CharacterIteratorFieldDelegate delegate = new
                          CharacterIteratorFieldDelegate();
 
@@ -1130,7 +1137,7 @@ public class SimpleDateFormat extends DateFormat {
      * Private member function that does the real date/time formatting.
      */
     private void subFormat(int patternCharIndex, int count,
-                           FieldDelegate delegate, StringBuffer buffer,
+                           FieldDelegate delegate, StringBuf buffer,
                            boolean useDateFormatSymbols)
     {
         int     maxIntCount = Integer.MAX_VALUE;
@@ -1320,7 +1327,11 @@ public class SimpleDateFormat extends DateFormat {
             }
 
             int num = (value / 60) * 100 + (value % 60);
-            CalendarUtils.sprintf0d(buffer, num, width);
+            if (buffer.isProxyStringBuilder()) {
+                CalendarUtils.sprintf0d(buffer.asStringBuilder(), num, width);
+            } else {
+                CalendarUtils.sprintf0d(buffer.asStringBuffer(), num, width);
+            }
             break;
 
         case PATTERN_ISO_ZONE:   // 'X'
@@ -1340,7 +1351,11 @@ public class SimpleDateFormat extends DateFormat {
                 value = -value;
             }
 
-            CalendarUtils.sprintf0d(buffer, value / 60, 2);
+            if (buffer.isProxyStringBuilder()) {
+                CalendarUtils.sprintf0d(buffer.asStringBuilder(), value / 60, 2);
+            } else {
+                CalendarUtils.sprintf0d(buffer.asStringBuffer(), value / 60, 2);
+            }
             if (count == 1) {
                 break;
             }
@@ -1348,7 +1363,11 @@ public class SimpleDateFormat extends DateFormat {
             if (count == 3) {
                 buffer.append(':');
             }
-            CalendarUtils.sprintf0d(buffer, value % 60, 2);
+            if (buffer.isProxyStringBuilder()) {
+                CalendarUtils.sprintf0d(buffer.asStringBuilder(), value % 60, 2);
+            } else {
+                CalendarUtils.sprintf0d(buffer.asStringBuffer(), value % 60, 2);
+            }
             break;
 
         default:
@@ -1382,7 +1401,7 @@ public class SimpleDateFormat extends DateFormat {
     /**
      * Formats a number with the specified minimum and maximum number of digits.
      */
-    private void zeroPaddingNumber(int value, int minDigits, int maxDigits, StringBuffer buffer)
+    private void zeroPaddingNumber(int value, int minDigits, int maxDigits, StringBuf buffer)
     {
         // Optimization for 1, 2 and 4 digit numbers. This should
         // cover most cases of formatting date/time related items.
@@ -1425,7 +1444,17 @@ public class SimpleDateFormat extends DateFormat {
 
         numberFormat.setMinimumIntegerDigits(minDigits);
         numberFormat.setMaximumIntegerDigits(maxDigits);
-        numberFormat.format((long)value, buffer, DontCareFieldPosition.INSTANCE);
+        if (buffer.isProxyStringBuilder()) {
+            //User can set numberFormat with a user-defined NumberFormat which
+            //not override format(long, StringBuf, FieldPosition).
+            if ("java.text".equals(numberFormat.getClass().getPackageName())) {
+                numberFormat.format((long) value, buffer, DontCareFieldPosition.INSTANCE);
+            } else {
+                buffer.append(numberFormat.format((long) value, new StringBuffer(), DontCareFieldPosition.INSTANCE));
+            }
+        } else {
+            numberFormat.format((long) value, buffer.asStringBuffer(), DontCareFieldPosition.INSTANCE);
+        }
     }
 
 
@@ -2565,5 +2594,4 @@ public class SimpleDateFormat extends DateFormat {
             originalNumberFormat = numberFormat;
         }
     }
-
 }

src/java.base/share/classes/java/text/StringBufFactory.java

@@ -0,0 +1,216 @@
+/*
+ * Copyright (c) 2024, Alibaba Group Holding Limited. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package java.text;
+
+import java.text.Format.StringBuf;
+
+/**
+ * {@code StringBufFactory} creates implementations of {@code Format.StringBuf},
+ * which is an interface with the minimum overlap required to support {@code StringBuffer}
+ * and {@code StringBuilder} in {@code Format}. This allows for {@code StringBuilder} to be used
+ * in place of {@code StringBuffer} to provide performance benefits for JDK internal
+ * {@code Format} subclasses.
+ */
+final class StringBufFactory {
+
+    private StringBufFactory() {
+    }
+
+    static StringBuf of(StringBuffer sb) {
+        return new StringBufferImpl(sb);
+    }
+
+    static StringBuf of(StringBuilder sb) {
+        return new StringBuilderImpl(sb);
+    }
+
+    static StringBuf of() {
+        return new StringBuilderImpl();
+    }
+
+    final static class StringBufferImpl implements StringBuf {
+        private final StringBuffer sb;
+
+        StringBufferImpl(StringBuffer sb) {
+            this.sb = sb;
+        }
+
+        @Override
+        public int length() {
+            return sb.length();
+        }
+
+        @Override
+        public String substring(int start, int end) {
+            return sb.substring(start, end);
+        }
+
+        @Override
+        public String substring(int start) {
+            return sb.substring(start);
+        }
+
+        @Override
+        public StringBuf append(char c) {
+            sb.append(c);
+            return this;
+        }
+
+        @Override
+        public StringBuf append(String str) {
+            sb.append(str);
+            return this;
+        }
+
+        @Override
+        public StringBuf append(int i) {
+            sb.append(i);
+            return this;
+        }
+
+        @Override
+        public StringBuf append(char[] str, int offset, int len) {
+            sb.append(str, offset, len);
+            return this;
+        }
+
+        @Override
+        public StringBuf append(CharSequence s, int start, int end) {
+            sb.append(s, start, end);
+            return this;
+        }
+
+        @Override
+        public StringBuf append(StringBuffer asb) {
+            sb.append(asb);
+            return this;
+        }
+
+        @Override
+        public boolean isProxyStringBuilder() {
+            return false;
+        }
+
+        @Override
+        public StringBuffer asStringBuffer() {
+            return sb;
+        }
+
+        @Override
+        public StringBuilder asStringBuilder() {
+            throw new AssertionError("Can't cast StringBuffer to StringBuilder");
+        }
+
+        @Override
+        public String toString() {
+            return sb.toString();
+        }
+    }
+
+    final static class StringBuilderImpl implements StringBuf {
+        private final StringBuilder sb;
+
+        StringBuilderImpl(StringBuilder sb) {
+            this.sb = sb;
+        }
+
+        StringBuilderImpl() {
+            this.sb = new StringBuilder();
+        }
+
+        @Override
+        public int length() {
+            return sb.length();
+        }
+
+        @Override
+        public String substring(int start, int end) {
+            return sb.substring(start, end);
+        }
+
+        @Override
+        public String substring(int start) {
+            return sb.substring(start);
+        }
+
+        @Override
+        public StringBuf append(char c) {
+            sb.append(c);
+            return this;
+        }
+
+        @Override
+        public StringBuf append(String str) {
+            sb.append(str);
+            return this;
+        }
+
+        @Override
+        public StringBuf append(int i) {
+            sb.append(i);
+            return this;
+        }
+
+        @Override
+        public StringBuf append(char[] str, int offset, int len) {
+            sb.append(str, offset, len);
+            return this;
+        }
+
+        @Override
+        public StringBuf append(CharSequence s, int start, int end) {
+            sb.append(s, start, end);
+            return this;
+        }
+
+        @Override
+        public StringBuf append(StringBuffer asb) {
+            sb.append(asb);
+            return this;
+        }
+
+
+        @Override
+        public boolean isProxyStringBuilder() {
+            return true;
+        }
+
+        @Override
+        public StringBuffer asStringBuffer() {
+            throw new AssertionError("Can't cast StringBuilder to StringBuffer");
+        }
+
+        @Override
+        public StringBuilder asStringBuilder() {
+            return sb;
+        }
+
+        @Override
+        public String toString() {
+            return sb.toString();
+        }
+    }
+}

test/micro/org/openjdk/bench/java/text/DateFormatterBench.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 2024, Alibaba Group Holding Limited. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package org.openjdk.bench.java.text;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+import org.openjdk.jmh.runner.Runner;
+import org.openjdk.jmh.runner.options.Options;
+import org.openjdk.jmh.runner.options.OptionsBuilder;
+
+import java.text.DateFormat;
+import java.util.Date;
+import java.util.Locale;
+import java.util.concurrent.TimeUnit;
+
+@BenchmarkMode(Mode.Throughput)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
+@Warmup(iterations = 5, time = 1)
+@Measurement(iterations = 5, time = 1)
+@Fork(3)
+@State(Scope.Benchmark)
+public class DateFormatterBench {
+
+    private Date date;
+
+    private Object objDate;
+
+    @Setup
+    public void setup() {
+        date = new Date();
+        objDate = new Date();
+    }
+
+    private DateFormat dateFormat = DateFormat.getDateInstance(DateFormat.FULL, Locale.ENGLISH);
+
+    @Benchmark
+    public String testFormatDate() {
+        return dateFormat.format(date);
+    }
+
+    @Benchmark
+    public String testFormatObject() {
+        return dateFormat.format(objDate);
+    }
+
+    public static void main(String... args) throws Exception {
+        Options opts = new OptionsBuilder().include(DateFormatterBench.class.getSimpleName()).shouldDoGC(true).build();
+        new Runner(opts).run();
+    }
+}

test/micro/org/openjdk/bench/java/text/ListFormatterBench.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2024, Alibaba Group Holding Limited. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package org.openjdk.bench.java.text;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+import org.openjdk.jmh.runner.Runner;
+import org.openjdk.jmh.runner.options.Options;
+import org.openjdk.jmh.runner.options.OptionsBuilder;
+
+import java.text.ListFormat;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+
+@BenchmarkMode(Mode.Throughput)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
+@Warmup(iterations = 5, time = 1)
+@Measurement(iterations = 5, time = 1)
+@Fork(3)
+@State(Scope.Benchmark)
+public class ListFormatterBench {
+
+    private List<String> data;
+
+    @Setup
+    public void setup() {
+        data = List.of("foo", "bar", "baz", "qux", "quux", "quuz");
+    }
+
+    private ListFormat listFormat = ListFormat.getInstance();
+
+    @Benchmark
+    public String testListFormat() {
+        return listFormat.format(data);
+    }
+
+    public static void main(String... args) throws Exception {
+        Options opts = new OptionsBuilder().include(ListFormatterBench.class.getSimpleName()).shouldDoGC(true).build();
+        new Runner(opts).run();
+    }
+}

test/micro/org/openjdk/bench/java/text/MessageFormatterBench.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 2024, Alibaba Group Holding Limited. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package org.openjdk.bench.java.text;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OperationsPerInvocation;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+import org.openjdk.jmh.infra.Blackhole;
+import org.openjdk.jmh.runner.Runner;
+import org.openjdk.jmh.runner.options.Options;
+import org.openjdk.jmh.runner.options.OptionsBuilder;
+
+import java.text.MessageFormat;
+import java.util.Locale;
+import java.util.concurrent.TimeUnit;
+
+@BenchmarkMode(Mode.Throughput)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
+@Warmup(iterations = 5, time = 1)
+@Measurement(iterations = 5, time = 1)
+@Fork(3)
+@State(Scope.Benchmark)
+public class MessageFormatterBench {
+
+    private Object[][] values;
+
+    @Setup
+    public void setup() {
+        values = new Object[][]{
+                new Object[]{Integer.valueOf(13), "MyDisk1"},
+                new Object[]{Float.valueOf(25.6f), "MyDisk2"},
+                new Object[]{Double.valueOf(123.89), "MyDisk3"},
+                new Object[]{Long.valueOf(1234567), "MyDisk4"},
+        };
+    }
+
+    private MessageFormat messageFormat = new MessageFormat("There is {0} GB of free space on the {1}.", Locale.ENGLISH);
+
+    @Benchmark
+    @OperationsPerInvocation(4)
+    public void testMessageFormat(final Blackhole bh) {
+        for (Object[] value : values) {
+            bh.consume(messageFormat.format(value));
+        }
+    }
+
+    public static void main(String... args) throws Exception {
+        Options opts = new OptionsBuilder().include(MessageFormatterBench.class.getSimpleName()).shouldDoGC(true).build();
+        new Runner(opts).run();
+    }
+}