8134373: use collections convenience factories in the JDK

Reviewed-by: scolebourne, prappo, dfuchs, redestad, smarks

jdk/src/java.base/share/classes/java/lang/module/ModuleFinder.java

@@ -33,7 +33,6 @@ import java.nio.file.Paths;
 import java.security.AccessController;
 import java.security.Permission;
 import java.security.PrivilegedAction;
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -333,7 +332,7 @@ public interface ModuleFinder {
      *
      * <p> When locating modules then any exceptions or errors thrown by the
      * {@code find} or {@code findAll} methods of the underlying module finders
-     * will be propogated to the caller of the resulting module finder's
+     * will be propagated to the caller of the resulting module finder's
      * {@code find} or {@code findAll} methods. </p>
      *
      * @param finders
@@ -342,8 +341,8 @@ public interface ModuleFinder {
      * @return A {@code ModuleFinder} that composes a sequence of module finders
      */
     static ModuleFinder compose(ModuleFinder... finders) {
-        final List<ModuleFinder> finderList = Arrays.asList(finders);
+        // copy the list, also checking for nulls
-        finderList.forEach(Objects::requireNonNull);
+        final List<ModuleFinder> finderList = List.of(finders);
 
         return new ModuleFinder() {
             private final Map<String, ModuleReference> nameToModule = new HashMap<>();

jdk/src/java.base/share/classes/java/net/CookieManager.java

@@ -81,7 +81,7 @@ import sun.util.logging.PlatformLogger;
  *   <li>
  *     Currently, only CookieStore.add(URI, HttpCookie) and CookieStore.get(URI)
  *     are used by CookieManager. Others are for completeness and might be needed
- *     by a more sophisticated CookieStore implementation, e.g. a NetscapeCookieSotre.
+ *     by a more sophisticated CookieStore implementation, e.g. a NetscapeCookieStore.
  *   </li>
  * </ul>
  * </blockquote>
@@ -201,10 +201,9 @@ public class CookieManager extends CookieHandler
             throw new IllegalArgumentException("Argument is null");
         }
 
-        Map<String, List<String>> cookieMap = new java.util.HashMap<>();
         // if there's no default CookieStore, no way for us to get any cookie
         if (cookieJar == null)
-            return Collections.unmodifiableMap(cookieMap);
+            return Map.of();
 
         boolean secureLink = "https".equalsIgnoreCase(uri.getScheme());
         List<HttpCookie> cookies = new java.util.ArrayList<>();
@@ -244,8 +243,7 @@ public class CookieManager extends CookieHandler
         // apply sort rule (RFC 2965 sec. 3.3.4)
         List<String> cookieHeader = sortByPath(cookies);
 
-        cookieMap.put("Cookie", cookieHeader);
+        return Map.of("Cookie", cookieHeader);
-        return Collections.unmodifiableMap(cookieMap);
     }
 
     public void

jdk/src/java.base/share/classes/java/nio/file/FileTreeIterator.java

@@ -31,11 +31,10 @@ import java.io.UncheckedIOException;
 import java.util.Arrays;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
-import java.util.Objects;
 import java.nio.file.FileTreeWalker.Event;
 
 /**
- * An {@code Iterator to iterate over the nodes of a file tree.
+ * An {@code Iterator} to iterate over the nodes of a file tree.
  *
  * <pre>{@code
  *     try (FileTreeIterator iterator = new FileTreeIterator(start, maxDepth, options)) {
@@ -62,7 +61,7 @@ class FileTreeIterator implements Iterator<Event>, Closeable {
      * @throws  SecurityException
      *          if the security manager denies access to the starting file
      * @throws  NullPointerException
-     *          if {@code start} or {@code options} is {@ocde null} or
+     *          if {@code start} or {@code options} is {@code null} or
      *          the options array contains a {@code null} element
      */
     FileTreeIterator(Path start, int maxDepth, FileVisitOption... options)

jdk/src/java.base/share/classes/java/nio/file/FileTreeWalker.java

@@ -171,7 +171,7 @@ class FileTreeWalker implements Closeable {
      *          if {@code options} contains an element that is not a
      *          {@code FileVisitOption}
      * @throws  NullPointerException
-     *          if {@code options} is {@ocde null} or the options
+     *          if {@code options} is {@code null} or the options
      *          array contains a {@code null} element
      */
     FileTreeWalker(Collection<FileVisitOption> options, int maxDepth) {

jdk/src/java.base/share/classes/java/security/Signature.java

@@ -37,7 +37,6 @@ import java.nio.ByteBuffer;
 import java.security.Provider.Service;
 
 import javax.crypto.Cipher;
-import javax.crypto.CipherSpi;
 import javax.crypto.IllegalBlockSizeException;
 import javax.crypto.BadPaddingException;
 import javax.crypto.NoSuchPaddingException;
@@ -180,15 +179,12 @@ public abstract class Signature extends SignatureSpi {
     private static final String RSA_CIPHER = "RSA/ECB/PKCS1Padding";
 
     // all the services we need to lookup for compatibility with Cipher
-    private static final List<ServiceId> rsaIds = Arrays.asList(
+    private static final List<ServiceId> rsaIds = List.of(
-        new ServiceId[] {
+        new ServiceId("Signature", "NONEwithRSA"),
-            new ServiceId("Signature", "NONEwithRSA"),
+        new ServiceId("Cipher", "RSA/ECB/PKCS1Padding"),
-            new ServiceId("Cipher", "RSA/ECB/PKCS1Padding"),
+        new ServiceId("Cipher", "RSA/ECB"),
-            new ServiceId("Cipher", "RSA/ECB"),
+        new ServiceId("Cipher", "RSA//PKCS1Padding"),
-            new ServiceId("Cipher", "RSA//PKCS1Padding"),
+        new ServiceId("Cipher", "RSA"));
-            new ServiceId("Cipher", "RSA"),
-        }
-    );
 
     /**
      * Returns a Signature object that implements the specified signature

jdk/src/java.base/share/classes/java/time/Duration.java

@@ -88,8 +88,6 @@ import java.time.temporal.Temporal;
 import java.time.temporal.TemporalAmount;
 import java.time.temporal.TemporalUnit;
 import java.time.temporal.UnsupportedTemporalTypeException;
-import java.util.Arrays;
-import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
 import java.util.regex.Matcher;
@@ -578,8 +576,7 @@ public final class Duration
      * the simple initialization in Duration.
      */
     private static class DurationUnits {
-        static final List<TemporalUnit> UNITS =
+        static final List<TemporalUnit> UNITS = List.of(SECONDS, NANOS);
-                Collections.unmodifiableList(Arrays.<TemporalUnit>asList(SECONDS, NANOS));
     }
 
     //-----------------------------------------------------------------------

jdk/src/java.base/share/classes/java/time/Period.java

@@ -83,8 +83,6 @@ import java.time.temporal.TemporalAmount;
 import java.time.temporal.TemporalQueries;
 import java.time.temporal.TemporalUnit;
 import java.time.temporal.UnsupportedTemporalTypeException;
-import java.util.Arrays;
-import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
 import java.util.regex.Matcher;
@@ -152,8 +150,7 @@ public final class Period
     /**
      * The set of supported units.
      */
-    private static final List<TemporalUnit> SUPPORTED_UNITS =
+    private static final List<TemporalUnit> SUPPORTED_UNITS = List.of(YEARS, MONTHS, DAYS);
-            Collections.unmodifiableList(Arrays.<TemporalUnit>asList(YEARS, MONTHS, DAYS));
 
     /**
      * The number of years.

jdk/src/java.base/share/classes/java/time/ZoneId.java

@@ -76,14 +76,14 @@ import java.time.temporal.UnsupportedTemporalTypeException;
 import java.time.zone.ZoneRules;
 import java.time.zone.ZoneRulesException;
 import java.time.zone.ZoneRulesProvider;
-import java.util.Collections;
-import java.util.HashMap;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
 import java.util.TimeZone;
 
+import static java.util.Map.entry;
+
 /**
  * A time-zone ID, such as {@code Europe/Paris}.
  * <p>
@@ -220,39 +220,36 @@ public abstract class ZoneId implements Serializable {
      * </ul>
      * The map is unmodifiable.
      */
-    public static final Map<String, String> SHORT_IDS;
+    public static final Map<String, String> SHORT_IDS = Map.ofEntries(
-    static {
+        entry("ACT", "Australia/Darwin"),
-        Map<String, String> map = new HashMap<>(64);
+        entry("AET", "Australia/Sydney"),
-        map.put("ACT", "Australia/Darwin");
+        entry("AGT", "America/Argentina/Buenos_Aires"),
-        map.put("AET", "Australia/Sydney");
+        entry("ART", "Africa/Cairo"),
-        map.put("AGT", "America/Argentina/Buenos_Aires");
+        entry("AST", "America/Anchorage"),
-        map.put("ART", "Africa/Cairo");
+        entry("BET", "America/Sao_Paulo"),
-        map.put("AST", "America/Anchorage");
+        entry("BST", "Asia/Dhaka"),
-        map.put("BET", "America/Sao_Paulo");
+        entry("CAT", "Africa/Harare"),
-        map.put("BST", "Asia/Dhaka");
+        entry("CNT", "America/St_Johns"),
-        map.put("CAT", "Africa/Harare");
+        entry("CST", "America/Chicago"),
-        map.put("CNT", "America/St_Johns");
+        entry("CTT", "Asia/Shanghai"),
-        map.put("CST", "America/Chicago");
+        entry("EAT", "Africa/Addis_Ababa"),
-        map.put("CTT", "Asia/Shanghai");
+        entry("ECT", "Europe/Paris"),
-        map.put("EAT", "Africa/Addis_Ababa");
+        entry("IET", "America/Indiana/Indianapolis"),
-        map.put("ECT", "Europe/Paris");
+        entry("IST", "Asia/Kolkata"),
-        map.put("IET", "America/Indiana/Indianapolis");
+        entry("JST", "Asia/Tokyo"),
-        map.put("IST", "Asia/Kolkata");
+        entry("MIT", "Pacific/Apia"),
-        map.put("JST", "Asia/Tokyo");
+        entry("NET", "Asia/Yerevan"),
-        map.put("MIT", "Pacific/Apia");
+        entry("NST", "Pacific/Auckland"),
-        map.put("NET", "Asia/Yerevan");
+        entry("PLT", "Asia/Karachi"),
-        map.put("NST", "Pacific/Auckland");
+        entry("PNT", "America/Phoenix"),
-        map.put("PLT", "Asia/Karachi");
+        entry("PRT", "America/Puerto_Rico"),
-        map.put("PNT", "America/Phoenix");
+        entry("PST", "America/Los_Angeles"),
-        map.put("PRT", "America/Puerto_Rico");
+        entry("SST", "Pacific/Guadalcanal"),
-        map.put("PST", "America/Los_Angeles");
+        entry("VST", "Asia/Ho_Chi_Minh"),
-        map.put("SST", "Pacific/Guadalcanal");
+        entry("EST", "-05:00"),
-        map.put("VST", "Asia/Ho_Chi_Minh");
+        entry("MST", "-07:00"),
-        map.put("EST", "-05:00");
+        entry("HST", "-10:00")
-        map.put("MST", "-07:00");
+    );
-        map.put("HST", "-10:00");
-        SHORT_IDS = Collections.unmodifiableMap(map);
-    }
     /**
      * Serialization version.
      */

jdk/src/java.base/share/classes/java/time/chrono/ChronoPeriodImpl.java

@@ -77,8 +77,6 @@ import java.time.temporal.TemporalQueries;
 import java.time.temporal.TemporalUnit;
 import java.time.temporal.UnsupportedTemporalTypeException;
 import java.time.temporal.ValueRange;
-import java.util.Arrays;
-import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
 
@@ -105,8 +103,7 @@ final class ChronoPeriodImpl
     /**
      * The set of supported units.
      */
-    private static final List<TemporalUnit> SUPPORTED_UNITS =
+    private static final List<TemporalUnit> SUPPORTED_UNITS = List.of(YEARS, MONTHS, DAYS);
-            Collections.unmodifiableList(Arrays.<TemporalUnit>asList(YEARS, MONTHS, DAYS));
 
     /**
      * The chronology.

jdk/src/java.base/share/classes/java/time/chrono/HijrahChronology.java

@@ -59,10 +59,7 @@ package java.time.chrono;
 
 import static java.time.temporal.ChronoField.EPOCH_DAY;
 
-import java.io.File;
-import java.io.FileInputStream;
 import java.io.FilePermission;
-import java.io.IOException;
 import java.io.InputStream;
 import java.io.InvalidObjectException;
 import java.io.ObjectInputStream;
@@ -83,7 +80,6 @@ import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.Objects;
 import java.util.Properties;
 
 import sun.util.logging.PlatformLogger;
@@ -512,7 +508,7 @@ public final class HijrahChronology extends AbstractChronology implements Serial
 
     @Override
     public List<Era> eras() {
-        return Arrays.<Era>asList(HijrahEra.values());
+        return List.of(HijrahEra.values());
     }
 
     //-----------------------------------------------------------------------

jdk/src/java.base/share/classes/java/time/chrono/IsoChronology.java

@@ -90,7 +90,6 @@ import java.time.temporal.ChronoField;
 import java.time.temporal.TemporalAccessor;
 import java.time.temporal.TemporalField;
 import java.time.temporal.ValueRange;
-import java.util.Arrays;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
@@ -492,7 +491,7 @@ public final class IsoChronology extends AbstractChronology implements Serializa
 
     @Override
     public List<Era> eras() {
-        return Arrays.<Era>asList(IsoEra.values());
+        return List.of(IsoEra.values());
     }
 
     //-----------------------------------------------------------------------

jdk/src/java.base/share/classes/java/time/chrono/JapaneseChronology.java

@@ -81,7 +81,6 @@ import java.time.temporal.TemporalAdjusters;
 import java.time.temporal.TemporalField;
 import java.time.temporal.UnsupportedTemporalTypeException;
 import java.time.temporal.ValueRange;
-import java.util.Arrays;
 import java.util.Calendar;
 import java.util.List;
 import java.util.Locale;
@@ -379,7 +378,7 @@ public final class JapaneseChronology extends AbstractChronology implements Seri
 
     @Override
     public List<Era> eras() {
-        return Arrays.<Era>asList(JapaneseEra.values());
+        return List.of(JapaneseEra.values());
     }
 
     JapaneseEra getCurrentEra() {

jdk/src/java.base/share/classes/java/time/chrono/MinguoChronology.java

@@ -72,7 +72,6 @@ import java.time.temporal.ChronoField;
 import java.time.temporal.TemporalAccessor;
 import java.time.temporal.TemporalField;
 import java.time.temporal.ValueRange;
-import java.util.Arrays;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
@@ -306,7 +305,7 @@ public final class MinguoChronology extends AbstractChronology implements Serial
 
     @Override
     public List<Era> eras() {
-        return Arrays.<Era>asList(MinguoEra.values());
+        return List.of(MinguoEra.values());
     }
 
     //-----------------------------------------------------------------------

jdk/src/java.base/share/classes/java/time/chrono/ThaiBuddhistChronology.java

@@ -342,7 +342,7 @@ public final class ThaiBuddhistChronology extends AbstractChronology implements
 
     @Override
     public List<Era> eras() {
-        return Arrays.<Era>asList(ThaiBuddhistEra.values());
+        return List.of(ThaiBuddhistEra.values());
     }
 
     //-----------------------------------------------------------------------

jdk/src/java.base/share/classes/java/time/format/DateTimeFormatter.java

@@ -1685,6 +1685,7 @@ public final class DateTimeFormatter {
     public DateTimeFormatter withResolverFields(TemporalField... resolverFields) {
         Set<TemporalField> fields = null;
         if (resolverFields != null) {
+            // Set.of cannot be used because it is hostile to nulls and duplicate elements
             fields = Collections.unmodifiableSet(new HashSet<>(Arrays.asList(resolverFields)));
         }
         if (Objects.equals(this.resolverFields, fields)) {

jdk/src/java.base/share/classes/java/time/zone/ZoneOffsetTransition.java

@@ -387,9 +387,9 @@ public final class ZoneOffsetTransition
      */
     List<ZoneOffset> getValidOffsets() {
         if (isGap()) {
-            return Collections.emptyList();
+            return List.of();
         }
-        return Arrays.asList(getOffsetBefore(), getOffsetAfter());
+        return List.of(getOffsetBefore(), getOffsetAfter());
     }
 
     //-----------------------------------------------------------------------

jdk/src/java.base/share/classes/java/time/zone/ZoneRules.java

@@ -303,7 +303,6 @@ public final class ZoneRules implements Serializable {
      * Creates an instance of ZoneRules that has fixed zone rules.
      *
      * @param offset  the offset this fixed zone rules is based on, not null
-     * @return the zone rules, not null
      * @see #isFixedOffset()
      */
     private ZoneRules(ZoneOffset offset) {
@@ -970,7 +969,7 @@ public final class ZoneRules implements Serializable {
      * @return an immutable list of transition rules, not null
      */
     public List<ZoneOffsetTransitionRule> getTransitionRules() {
-        return Collections.unmodifiableList(Arrays.asList(lastRules));
+        return List.of(lastRules);
     }
 
     /**

jdk/src/java.base/share/classes/java/util/ResourceBundle.java

@@ -2491,34 +2491,29 @@ public abstract class ResourceBundle {
         /**
          * The default format <code>List</code>, which contains the strings
          * <code>"java.class"</code> and <code>"java.properties"</code>, in
-         * this order. This <code>List</code> is {@linkplain
+         * this order. This <code>List</code> is unmodifiable.
-         * Collections#unmodifiableList(List) unmodifiable}.
          *
          * @see #getFormats(String)
          */
         public static final List<String> FORMAT_DEFAULT
-            = Collections.unmodifiableList(Arrays.asList("java.class",
+            = List.of("java.class", "java.properties");
-                                                         "java.properties"));
 
         /**
          * The class-only format <code>List</code> containing
-         * <code>"java.class"</code>. This <code>List</code> is {@linkplain
+         * <code>"java.class"</code>. This <code>List</code> is unmodifiable.
-         * Collections#unmodifiableList(List) unmodifiable}.
          *
          * @see #getFormats(String)
          */
-        public static final List<String> FORMAT_CLASS
+        public static final List<String> FORMAT_CLASS = List.of("java.class");
-            = Collections.unmodifiableList(Arrays.asList("java.class"));
 
         /**
          * The properties-only format <code>List</code> containing
-         * <code>"java.properties"</code>. This <code>List</code> is
+         * <code>"java.properties"</code>. This <code>List</code> is unmodifiable.
-         * {@linkplain Collections#unmodifiableList(List) unmodifiable}.
          *
          * @see #getFormats(String)
          */
         public static final List<String> FORMAT_PROPERTIES
-            = Collections.unmodifiableList(Arrays.asList("java.properties"));
+            = List.of("java.properties");
 
         /**
          * The time-to-live constant for not caching loaded resource bundle

jdk/src/java.base/share/classes/java/util/stream/Collectors.java

@@ -27,7 +27,6 @@ package java.util.stream;
 import java.util.AbstractMap;
 import java.util.AbstractSet;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
@@ -1720,12 +1719,12 @@ public final class Collectors {
 
         @Override
         public Set<Map.Entry<Boolean, T>> entrySet() {
-            return new AbstractSet<Map.Entry<Boolean, T>>() {
+            return new AbstractSet<>() {
                 @Override
                 public Iterator<Map.Entry<Boolean, T>> iterator() {
                     Map.Entry<Boolean, T> falseEntry = new SimpleImmutableEntry<>(false, forFalse);
                     Map.Entry<Boolean, T> trueEntry = new SimpleImmutableEntry<>(true, forTrue);
-                    return Arrays.asList(falseEntry, trueEntry).iterator();
+                    return List.of(falseEntry, trueEntry).iterator();
                 }
 
                 @Override