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8221980: Simplify Optional implementation

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Reviewed-by: smarks, clanger
This commit is contained in:
Claes Redestad 2019-04-04 23:19:26 +02:00
parent fbba7c49b6
commit 3233a6f944
1 changed files with 9 additions and 16 deletions
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25
src/java.base/share/classes/java/util/Optional.java
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@ -61,23 +61,13 @@ public final class Optional<T> {
/**
* Common instance for {@code empty()}.
*/
private static final Optional<?> EMPTY = new Optional<>();
private static final Optional<?> EMPTY = new Optional<>(null);
/**
* If non-null, the value; if null, indicates no value is present
*/
private final T value;
/**
* Constructs an empty instance.
*
* @implNote Generally only one empty instance, {@link Optional#EMPTY},
* should exist per VM.
*/
private Optional() {
this.value = null;
}
/**
* Returns an empty {@code Optional} instance. No value is present for this
* {@code Optional}.
@ -100,11 +90,12 @@ public final class Optional<T> {
/**
* Constructs an instance with the described value.
*
* @param value the non-{@code null} value to describe
* @throws NullPointerException if value is {@code null}
* @param value the value to describe; it's the caller's responsibility to
* ensure the value is non-{@code null} unless creating the singleton
* instance returned by {@code empty()}.
*/
private Optional(T value) {
this.value = Objects.requireNonNull(value);
this.value = value;
}
/**
@ -117,7 +108,7 @@ public final class Optional<T> {
* @throws NullPointerException if value is {@code null}
*/
public static <T> Optional<T> of(T value) {
return new Optional<>(value);
return new Optional<>(Objects.requireNonNull(value));
}
/**
@ -129,8 +120,10 @@ public final class Optional<T> {
* @return an {@code Optional} with a present value if the specified value
* is non-{@code null}, otherwise an empty {@code Optional}
*/
@SuppressWarnings("unchecked")
public static <T> Optional<T> ofNullable(T value) {
return value == null ? empty() : of(value);
return value == null ? (Optional<T>) EMPTY
: new Optional<>(value);
}
/**