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Add purity annotations to Comparator. #295

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Merged
mernst merged 3 commits into from
Sep 30, 2026
Merged

Add purity annotations to Comparator. #295

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f47614d
Add purity annotations to Comparator.
smillst Sep 18, 2026
27774d5
Merge branch 'master' into side-effect-free-functional-params
mernst Sep 20, 2026
a7f32f3
Merge branch 'master' into side-effect-free-functional-params
smillst Sep 29, 2026
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15 changes: 15 additions & 0 deletions src/java.base/share/classes/java/util/Comparator.java
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Original file line number Diff line number Diff line change
Expand Up @@ -228,6 +228,7 @@ default Comparator<T> reversed() {
* @throws NullPointerException if the argument is null.
* @since 1.8
*/
@SideEffectFree
default Comparator<T> thenComparing(Comparator<? super T> other) {
Objects.requireNonNull(other);
return (Comparator<T> & Serializable) (c1, c2) -> {
Expand All @@ -253,6 +254,7 @@ default Comparator<T> thenComparing(Comparator<? super T> other) {
* @see #thenComparing(Comparator)
* @since 1.8
*/
@SideEffectFree
default <U> Comparator<T> thenComparing(
Function<? super T, ? extends U> keyExtractor,
Comparator<? super U> keyComparator)
Expand All @@ -277,6 +279,7 @@ default <U> Comparator<T> thenComparing(
* @see #thenComparing(Comparator)
* @since 1.8
*/
@SideEffectFree
default <U extends Comparable<? super U>> Comparator<T> thenComparing(
Function<? super T, ? extends U> keyExtractor)
{
Expand All @@ -298,6 +301,7 @@ default <U extends Comparable<? super U>> Comparator<T> thenComparing(
* @see #thenComparing(Comparator)
* @since 1.8
*/
@SideEffectFree
default Comparator<T> thenComparingInt(ToIntFunction<? super T> keyExtractor) {
return thenComparing(comparingInt(keyExtractor));
}
Expand All @@ -317,6 +321,7 @@ default Comparator<T> thenComparingInt(ToIntFunction<? super T> keyExtractor) {
* @see #thenComparing(Comparator)
* @since 1.8
*/
@SideEffectFree
default Comparator<T> thenComparingLong(ToLongFunction<? super T> keyExtractor) {
return thenComparing(comparingLong(keyExtractor));
}
Expand All @@ -336,6 +341,7 @@ default Comparator<T> thenComparingLong(ToLongFunction<? super T> keyExtractor)
* @see #thenComparing(Comparator)
* @since 1.8
*/
@SideEffectFree
default Comparator<T> thenComparingDouble(ToDoubleFunction<? super T> keyExtractor) {
return thenComparing(comparingDouble(keyExtractor));
}
Expand All @@ -353,6 +359,7 @@ default Comparator<T> thenComparingDouble(ToDoubleFunction<? super T> keyExtract
* @see Comparable
* @since 1.8
*/
@Pure
public static <T extends Comparable<? super T>> Comparator<T> reverseOrder() {
return Collections.reverseOrder();
}
Expand All @@ -370,6 +377,7 @@ public static <T extends Comparable<? super T>> Comparator<T> reverseOrder() {
* @see Comparable
* @since 1.8
*/
@Pure
@SuppressWarnings("unchecked")
public static <T extends Comparable<@NonNull ? super @NonNull T>> Comparator<T> naturalOrder() {
return (Comparator<T>) Comparators.NaturalOrderComparator.INSTANCE;
Expand All @@ -392,6 +400,7 @@ public static <T extends Comparable<? super T>> Comparator<T> reverseOrder() {
* {@code Comparator}.
* @since 1.8
*/
@SideEffectFree
public static <T> Comparator<@Nullable T> nullsFirst(@Nullable Comparator<? super T> comparator) {
return new Comparators.NullComparator<>(true, comparator);
}
Expand All @@ -413,6 +422,7 @@ public static <T extends Comparable<? super T>> Comparator<T> reverseOrder() {
* {@code Comparator}.
* @since 1.8
*/
@SideEffectFree
public static <T> Comparator<@Nullable T> nullsLast(@Nullable Comparator<? super T> comparator) {
return new Comparators.NullComparator<>(false, comparator);
}
Expand Down Expand Up @@ -444,6 +454,7 @@ public static <T extends Comparable<? super T>> Comparator<T> reverseOrder() {
* @throws NullPointerException if either argument is null
* @since 1.8
*/
@SideEffectFree
public static <T, U> Comparator<T> comparing(
Function<? super T, ? extends U> keyExtractor,
Comparator<? super U> keyComparator)
Expand Down Expand Up @@ -479,6 +490,7 @@ public static <T, U> Comparator<T> comparing(
* @throws NullPointerException if the argument is null
* @since 1.8
*/
@SideEffectFree
public static <T, U extends Comparable<? super U>> Comparator<T> comparing(
Function<? super T, ? extends U> keyExtractor)
{
Expand All @@ -502,6 +514,7 @@ public static <T, U extends Comparable<? super U>> Comparator<T> comparing(
* @throws NullPointerException if the argument is null
* @since 1.8
*/
@SideEffectFree
public static <T> Comparator<T> comparingInt(ToIntFunction<? super T> keyExtractor) {
Objects.requireNonNull(keyExtractor);
return (Comparator<T> & Serializable)
Expand All @@ -523,6 +536,7 @@ public static <T> Comparator<T> comparingInt(ToIntFunction<? super T> keyExtract
* @throws NullPointerException if the argument is null
* @since 1.8
*/
@SideEffectFree
public static <T> Comparator<T> comparingLong(ToLongFunction<? super T> keyExtractor) {
Objects.requireNonNull(keyExtractor);
return (Comparator<T> & Serializable)
Expand All @@ -544,6 +558,7 @@ public static <T> Comparator<T> comparingLong(ToLongFunction<? super T> keyExtra
* @throws NullPointerException if the argument is null
* @since 1.8
*/
@SideEffectFree
public static<T> Comparator<T> comparingDouble(ToDoubleFunction<? super T> keyExtractor) {
Objects.requireNonNull(keyExtractor);
return (Comparator<T> & Serializable)
Expand Down
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