8311188: Simplify and modernize equals and hashCode in java.text

Reviewed-by: lancea, naoto, rriggs

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2023, 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
@@ -618,7 +618,7 @@ public class AttributedString {
                 int currIndex = runIndex;
                 int runStart = runStarts[currIndex];
                 while (runStart >= beginIndex &&
-                        valuesMatch(value, getAttribute(attribute, currIndex - 1))) {
+                        Objects.equals(value, getAttribute(attribute, currIndex - 1))) {
                     currIndex--;
                     runStart = runStarts[currIndex];
                 }
@@ -632,7 +632,7 @@ public class AttributedString {
                 int currIndex = runIndex;
                 int runLimit = (currIndex < runCount - 1) ? runStarts[currIndex + 1] : textLength;
                 while (runLimit <= endIndex &&
-                        valuesMatch(value, getAttribute(attribute, currIndex + 1))) {
+                        Objects.equals(value, getAttribute(attribute, currIndex + 1))) {
                     currIndex++;
                     runLimit = (currIndex < runCount - 1) ? runStarts[currIndex + 1] : textLength;
                 }
@@ -650,22 +650,13 @@ public class AttributedString {
     // returns whether all specified attributes have equal values in the runs with the given indices
     private boolean attributeValuesMatch(Set<? extends Attribute> attributes, int runIndex1, int runIndex2) {
         for (Attribute key : attributes) {
-            if (!valuesMatch(getAttribute(key, runIndex1), getAttribute(key, runIndex2))) {
+            if (!Objects.equals(getAttribute(key, runIndex1), getAttribute(key, runIndex2))) {
                 return false;
             }
         }
         return true;
     }
 
-    // returns whether the two objects are either both null or equal
-    private static final boolean valuesMatch(Object value1, Object value2) {
-        if (value1 == null) {
-            return value2 == null;
-        } else {
-            return value1.equals(value2);
-        }
-    }
-
     /**
      * Appends the contents of the CharacterIterator iterator into the
      * StringBuilder buf.
@@ -760,6 +751,7 @@ public class AttributedString {
 
         // Object methods. See documentation in that class.
 
+        @Override
         public boolean equals(Object obj) {
             if (this == obj) {
                 return true;
@@ -775,6 +767,7 @@ public class AttributedString {
             return true;
         }
 
+        @Override
         public int hashCode() {
             return text.hashCode() ^ currentIndex ^ beginIndex ^ endIndex;
         }
@@ -861,7 +854,7 @@ public class AttributedString {
                 int runStart = currentRunStart;
                 int runIndex = currentRunIndex;
                 while (runStart > beginIndex &&
-                        valuesMatch(value, AttributedString.this.getAttribute(attribute, runIndex - 1))) {
+                        Objects.equals(value, AttributedString.this.getAttribute(attribute, runIndex - 1))) {
                     runIndex--;
                     runStart = runStarts[runIndex];
                 }
@@ -902,7 +895,7 @@ public class AttributedString {
                 int runLimit = currentRunLimit;
                 int runIndex = currentRunIndex;
                 while (runLimit < endIndex &&
-                        valuesMatch(value, AttributedString.this.getAttribute(attribute, runIndex + 1))) {
+                        Objects.equals(value, AttributedString.this.getAttribute(attribute, runIndex + 1))) {
                     runIndex++;
                     runLimit = runIndex < runCount - 1 ? runStarts[runIndex + 1] : endIndex;
                 }
@@ -1081,11 +1074,10 @@ class AttributeEntry implements Map.Entry<Attribute,Object> {
         this.value = value;
     }
 
+    @Override
     public boolean equals(Object o) {
-        if (!(o instanceof AttributeEntry other)) {
+        return o instanceof AttributeEntry other
-            return false;
+                && other.key.equals(key) && Objects.equals(other.value, value);
-        }
-        return other.key.equals(key) && Objects.equals(other.value, value);
     }
 
     public Attribute getKey() {
@@ -1100,8 +1092,9 @@ class AttributeEntry implements Map.Entry<Attribute,Object> {
         throw new UnsupportedOperationException();
     }
 
+    @Override
     public int hashCode() {
-        return key.hashCode() ^ (value==null ? 0 : value.hashCode());
+        return key.hashCode() ^ Objects.hashCode(value);
     }
 
     public String toString() {

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

@@ -497,6 +497,7 @@ public class ChoiceFormat extends NumberFormat {
     /**
      * Generates a hash code for the message format object.
      */
+    @Override
     public int hashCode() {
         int result = choiceLimits.length;
         if (choiceFormats.length > 0) {
@@ -509,11 +510,11 @@ public class ChoiceFormat extends NumberFormat {
     /**
      * Equality comparison between two
      */
+    @Override
     public boolean equals(Object obj) {
-        if (obj == null) return false;
         if (this == obj)                      // quick check
             return true;
-        if (getClass() != obj.getClass())
+        if (obj == null || getClass() != obj.getClass())
             return false;
         ChoiceFormat other = (ChoiceFormat) obj;
         return (Arrays.equals(choiceLimits, other.choiceLimits)

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

@@ -530,10 +530,7 @@ public abstract class Collator
         if (this == that) {
             return true;
         }
-        if (that == null) {
+        if (that == null || getClass() != that.getClass()) {
-            return false;
-        }
-        if (getClass() != that.getClass()) {
             return false;
         }
         Collator other = (Collator) that;

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

@@ -2354,7 +2354,11 @@ public final class CompactNumberFormat extends NumberFormat {
     @Override
     public boolean equals(Object obj) {
 
-        if (!super.equals(obj)) {
+        if (this == obj) {
+            return true;
+        }
+
+        if (!super.equals(obj)) { // super does null and class checks
             return false;
         }
 
@@ -2369,9 +2373,7 @@ public final class CompactNumberFormat extends NumberFormat {
     }
 
     /**
-     * Returns the hash code for this {@code CompactNumberFormat} instance.
+     * {@return the hash code for this {@code CompactNumberFormat} instance}
-     *
-     * @return hash code for this {@code CompactNumberFormat}
      */
     @Override
     public int hashCode() {

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

@@ -683,6 +683,7 @@ public class DateFormatSymbols implements Serializable, Cloneable {
     /**
      * Override equals
      */
+    @Override
     public boolean equals(Object obj)
     {
         if (this == obj) return true;
@@ -695,10 +696,7 @@ public class DateFormatSymbols implements Serializable, Cloneable {
                 && Arrays.equals(shortWeekdays, that.shortWeekdays)
                 && Arrays.equals(ampms, that.ampms)
                 && Arrays.deepEquals(getZoneStringsWrapper(), that.getZoneStringsWrapper())
-                && ((localPatternChars != null
+                && Objects.equals(localPatternChars, that.localPatternChars));
-                  && localPatternChars.equals(that.localPatternChars))
-                 || (localPatternChars == null
-                  && that.localPatternChars == null)));
     }
 
     // =======================privates===============================

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

@@ -2918,10 +2918,13 @@ public class DecimalFormat extends NumberFormat {
     @Override
     public boolean equals(Object obj)
     {
-        if (obj == null)
+        if (this == obj) {
-            return false;
+            return true;
+        }
+
         if (!super.equals(obj))
-            return false; // super does class check
+            return false; // super does null and class checks
+
         DecimalFormat other = (DecimalFormat) obj;
         return ((posPrefixPattern == other.posPrefixPattern &&
                  positivePrefix.equals(other.positivePrefix))

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1996, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2023, 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
@@ -741,9 +741,8 @@ public class DecimalFormatSymbols implements Cloneable, Serializable {
      */
     @Override
     public boolean equals(Object obj) {
-        if (obj == null) return false;
         if (this == obj) return true;
-        if (getClass() != obj.getClass()) return false;
+        if (obj == null || getClass() != obj.getClass()) return false;
         DecimalFormatSymbols other = (DecimalFormatSymbols) obj;
         return (zeroDigit == other.zeroDigit &&
             groupingSeparator == other.groupingSeparator &&

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1996, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2023, 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
@@ -38,6 +38,8 @@
 
 package java.text;
 
+import java.util.Objects;
+
 /**
  * {@code FieldPosition} is a simple class used by {@code Format}
  * and its subclasses to identify fields in formatted output. Fields can
@@ -218,28 +220,22 @@ public class FieldPosition {
     /**
      * Overrides equals
      */
+    @Override
     public boolean equals(Object obj)
     {
-        if (obj == null) return false;
         if (!(obj instanceof FieldPosition other))
             return false;
-        if (attribute == null) {
+        if (!Objects.equals(attribute, other.attribute))
-            if (other.attribute != null) {
             return false;
-            }
-        }
-        else if (!attribute.equals(other.attribute)) {
-            return false;
-        }
         return (beginIndex == other.beginIndex
             && endIndex == other.endIndex
             && field == other.field);
     }
 
     /**
-     * Returns a hash code for this FieldPosition.
+     * {@return a hash code for this FieldPosition}
-     * @return a hash code value for this object
      */
+    @Override
     public int hashCode() {
         return (field << 24) | (beginIndex << 16) | endIndex;
     }
@@ -270,7 +266,7 @@ public class FieldPosition {
     /**
      * Return true if the receiver wants a {@code Format.Field} value and
      * {@code attribute} is equal to it, or true if the receiver
-     * represents an inteter constant and {@code field} equals it.
+     * represents an integer constant and {@code field} equals it.
      */
     private boolean matchesField(Format.Field attribute, int field) {
         if (this.attribute != null) {

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

@@ -47,6 +47,7 @@ import java.util.Arrays;
 import java.util.Date;
 import java.util.List;
 import java.util.Locale;
+import java.util.Objects;
 
 
 /**
@@ -1132,6 +1133,7 @@ public class MessageFormat extends Format {
     /**
      * Equality comparison between two message format objects
      */
+    @Override
     public boolean equals(Object obj) {
         if (this == obj)                      // quick check
             return true;
@@ -1140,8 +1142,7 @@ public class MessageFormat extends Format {
         MessageFormat other = (MessageFormat) obj;
         return (maxOffset == other.maxOffset
                 && pattern.equals(other.pattern)
-                && ((locale != null && locale.equals(other.locale))
+                && Objects.equals(locale,other.locale)
-                 || (locale == null && other.locale == null))
                 && Arrays.equals(offsets,other.offsets)
                 && Arrays.equals(argumentNumbers,other.argumentNumbers)
                 && Arrays.equals(formats,other.formats));
@@ -1150,6 +1151,7 @@ public class MessageFormat extends Format {
     /**
      * Generates a hash code for the message format object.
      */
+    @Override
     public int hashCode() {
         return pattern.hashCode(); // enough for reasonable distribution
     }

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

@@ -711,13 +711,10 @@ public abstract class NumberFormat extends Format  {
      */
     @Override
     public boolean equals(Object obj) {
-        if (obj == null) {
-            return false;
-        }
         if (this == obj) {
             return true;
         }
-        if (getClass() != obj.getClass()) {
+        if (obj == null || getClass() != obj.getClass()) {
             return false;
         }
         NumberFormat other = (NumberFormat) obj;

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1996, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2023, 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
@@ -122,18 +122,17 @@ public class ParsePosition {
     /**
      * Overrides equals
      */
+    @Override
     public boolean equals(Object obj)
     {
-        if (obj == null) return false;
+        return obj instanceof ParsePosition other
-        if (!(obj instanceof ParsePosition other))
+                && index == other.index && errorIndex == other.errorIndex;
-            return false;
-        return (index == other.index && errorIndex == other.errorIndex);
     }
 
     /**
-     * Returns a hash code for this ParsePosition.
+     * {@return a hash code for this ParsePosition}
-     * @return a hash code value for this object
      */
+    @Override
     public int hashCode() {
         return (errorIndex << 16) | index;
     }

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

@@ -729,9 +729,9 @@ public class RuleBasedCollator extends Collator{
      * @return true if the current table-based collation object is the same
      * as the table-based collation object obj; false otherwise.
      */
+    @Override
     public boolean equals(Object obj) {
-        if (obj == null) return false;
+        if (!super.equals(obj)) return false;  // super does null and class checks
-        if (!super.equals(obj)) return false;  // super does class check
         RuleBasedCollator other = (RuleBasedCollator) obj;
         // all other non-transient information is also contained in rules.
         return (getRules().equals(other.getRules()));
@@ -740,6 +740,7 @@ public class RuleBasedCollator extends Collator{
     /**
      * Generates the hash code for the table-based collation object
      */
+    @Override
     public int hashCode() {
         return getRules().hashCode();
     }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1996, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2023, 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
@@ -2409,9 +2409,7 @@ public class SimpleDateFormat extends DateFormat {
     }
 
     /**
-     * Returns the hash code value for this {@code SimpleDateFormat} object.
+     * {@return the hash code value for this {@code SimpleDateFormat} object}
-     *
-     * @return the hash code value for this {@code SimpleDateFormat} object.
      */
     @Override
     public int hashCode()
@@ -2431,7 +2429,7 @@ public class SimpleDateFormat extends DateFormat {
     public boolean equals(Object obj)
     {
         if (!super.equals(obj)) {
-            return false; // super does class check
+            return false; // super does null and class checks
         }
         SimpleDateFormat that = (SimpleDateFormat) obj;
         return (pattern.equals(that.pattern)

src/java.base/share/classes/sun/text/IntHashtable.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2023, 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
@@ -91,10 +91,11 @@ public final class IntHashtable {
         rehash();
     }
 
+    @Override
     public boolean equals (Object that) {
-        if (that.getClass() != this.getClass()) return false;
+        if (!(that instanceof IntHashtable other)) {
-
+            return false;
-        IntHashtable other = (IntHashtable) that;
+        }
         if (other.size() != count || other.defaultValue != defaultValue) {
             return false;
         }
@@ -106,6 +107,7 @@ public final class IntHashtable {
         return true;
     }
 
+    @Override
     public int hashCode() {
         // NOTE:  This function isn't actually used anywhere in this package, but it's here
         // in case this class is ever used to make sure we uphold the invariants about

src/java.base/share/classes/sun/text/RuleBasedBreakIterator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2023, 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
@@ -46,6 +46,8 @@ import java.text.BreakIterator;
 import java.text.CharacterIterator;
 import java.text.StringCharacterIterator;
 import java.util.MissingResourceException;
+import java.util.Objects;
+
 import sun.text.CompactByteArray;
 import sun.text.SupplementaryCharacterData;
 
@@ -498,24 +500,9 @@ public class RuleBasedBreakIterator extends BreakIterator {
      */
     @Override
     public boolean equals(Object that) {
-        try {
+        return that instanceof RuleBasedBreakIterator other
-            if (that == null) {
+                && checksum == other.checksum
-                return false;
+                && Objects.equals(text, other.text);
-            }
-
-            RuleBasedBreakIterator other = (RuleBasedBreakIterator) that;
-            if (checksum != other.checksum) {
-                return false;
-            }
-            if (text == null) {
-                return other.text == null;
-            } else {
-                return text.equals(other.text);
-            }
-        }
-        catch(ClassCastException e) {
-            return false;
-        }
     }
 
     /**
@@ -527,8 +514,7 @@ public class RuleBasedBreakIterator extends BreakIterator {
     }
 
     /**
-     * Compute a hashcode for this BreakIterator
+     * {@return hashcode for this BreakIterator}
-     * @return A hash code
      */
     @Override
     public int hashCode() {