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8140281: add no-arg Optional.orElseThrow() as preferred alternative to get()

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Reviewed-by: alanb, bpb, forax, darcy
This commit is contained in:
Stuart Marks 2017-12-13 18:47:20 -08:00
parent 0214135fde
commit feffd15dc2
8 changed files with 118 additions and 31 deletions
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26
src/java.base/share/classes/java/util/Optional.java
View file

@ -32,8 +32,9 @@ import java.util.stream.Stream;
/**
* A container object which may or may not contain a non-{@code null} value.
* If a value is present, {@code isPresent()} returns {@code true} and
* {@code get()} returns the value.
* If a value is present, {@code isPresent()} returns {@code true}. If no
* value is present, the object is considered <i>empty</i> and
* {@code isPresent()} returns {@code false}.
*
* <p>Additional methods that depend on the presence or absence of a contained
* value are provided, such as {@link #orElse(Object) orElse()}
@ -137,14 +138,10 @@ public final class Optional<T> {
* {@code NoSuchElementException}.
*
* @apiNote
* The methods {@link #orElse(Object) orElse} and
* {@link #orElseGet(Supplier) orElseGet}
* are generally preferable to this method, as they return a substitute
* value if the value is absent, instead of throwing an exception.
* The preferred alternative to this method is {@link #orElseThrow()}.
*
* @return the non-{@code null} value described by this {@code Optional}
* @throws NoSuchElementException if no value is present
* @see Optional#isPresent()
*/
public T get() {
if (value == null) {
@ -361,6 +358,21 @@ public final class Optional<T> {
return value != null ? value : supplier.get();
}
/**
* If a value is present, returns the value, otherwise throws
* {@code NoSuchElementException}.
*
* @return the non-{@code null} value described by this {@code Optional}
* @throws NoSuchElementException if no value is present
* @since 10
*/
public T orElseThrow() {
if (value == null) {
throw new NoSuchElementException("No value present");
}
return value;
}
/**
* If a value is present, returns the value, otherwise throws an exception
* produced by the exception supplying function.

28
src/java.base/share/classes/java/util/OptionalDouble.java
View file

@ -30,9 +30,10 @@ import java.util.function.Supplier;
import java.util.stream.DoubleStream;
/**
* A container object which may or may not contain a {@code double} value. If a
* value is present, {@code isPresent()} returns {@code true} and
* {@code getAsDouble()} returns the value.
* A container object which may or may not contain a {@code double} value.
* If a value is present, {@code isPresent()} returns {@code true}. If no
* value is present, the object is considered <i>empty</i> and
* {@code isPresent()} returns {@code false}.
*
* <p>Additional methods that depend on the presence or absence of a contained
* value are provided, such as {@link #orElse(double) orElse()}
@ -117,14 +118,10 @@ public final class OptionalDouble {
* {@code NoSuchElementException}.
*
* @apiNote
* The methods {@link #orElse(double) orElse} and
* {@link #orElseGet(DoubleSupplier) orElseGet}
* are generally preferable to this method, as they return a substitute
* value if the value is absent, instead of throwing an exception.
* The preferred alternative to this method is {@link #orElseThrow()}.
*
* @return the value described by this {@code OptionalDouble}
* @throws NoSuchElementException if no value is present
* @see OptionalDouble#isPresent()
*/
public double getAsDouble() {
if (!isPresent) {
@ -225,6 +222,21 @@ public final class OptionalDouble {
return isPresent ? value : supplier.getAsDouble();
}
/**
* If a value is present, returns the value, otherwise throws
* {@code NoSuchElementException}.
*
* @return the value described by this {@code OptionalDouble}
* @throws NoSuchElementException if no value is present
* @since 10
*/
public double orElseThrow() {
if (!isPresent) {
throw new NoSuchElementException("No value present");
}
return value;
}
/**
* If a value is present, returns the value, otherwise throws an exception
* produced by the exception supplying function.

28
src/java.base/share/classes/java/util/OptionalInt.java
View file

@ -30,9 +30,10 @@ import java.util.function.Supplier;
import java.util.stream.IntStream;
/**
* A container object which may or may not contain an {@code int} value. If a
* value is present, {@code isPresent()} returns {@code true} and
* {@code getAsInt()} returns the value.
* A container object which may or may not contain an {@code int} value.
* If a value is present, {@code isPresent()} returns {@code true}. If no
* value is present, the object is considered <i>empty</i> and
* {@code isPresent()} returns {@code false}.
*
* <p>Additional methods that depend on the presence or absence of a contained
* value are provided, such as {@link #orElse(int) orElse()}
@ -117,14 +118,10 @@ public final class OptionalInt {
* {@code NoSuchElementException}.
*
* @apiNote
* The methods {@link #orElse(int) orElse} and
* {@link #orElseGet(IntSupplier) orElseGet}
* are generally preferable to this method, as they return a substitute
* value if the value is absent, instead of throwing an exception.
* The preferred alternative to this method is {@link #orElseThrow()}.
*
* @return the value described by this {@code OptionalInt}
* @throws NoSuchElementException if no value is present
* @see OptionalInt#isPresent()
*/
public int getAsInt() {
if (!isPresent) {
@ -224,6 +221,21 @@ public final class OptionalInt {
return isPresent ? value : supplier.getAsInt();
}
/**
* If a value is present, returns the value, otherwise throws
* {@code NoSuchElementException}.
*
* @return the value described by this {@code OptionalInt}
* @throws NoSuchElementException if no value is present
* @since 10
*/
public int orElseThrow() {
if (!isPresent) {
throw new NoSuchElementException("No value present");
}
return value;
}
/**
* If a value is present, returns the value, otherwise throws an exception
* produced by the exception supplying function.

28
src/java.base/share/classes/java/util/OptionalLong.java
View file

@ -30,9 +30,10 @@ import java.util.function.Supplier;
import java.util.stream.LongStream;
/**
* A container object which may or may not contain a {@code long} value. If a
* value is present, {@code isPresent()} returns {@code true} and
* {@code getAsLong()} returns the value.
* A container object which may or may not contain a {@code long} value.
* If a value is present, {@code isPresent()} returns {@code true}. If no
* value is present, the object is considered <i>empty</i> and
* {@code isPresent()} returns {@code false}.
*
* <p>Additional methods that depend on the presence or absence of a contained
* value are provided, such as {@link #orElse(long) orElse()}
@ -117,14 +118,10 @@ public final class OptionalLong {
* {@code NoSuchElementException}.
*
* @apiNote
* The methods {@link #orElse(long) orElse} and
* {@link #orElseGet(LongSupplier) orElseGet}
* are generally preferable to this method, as they return a substitute
* value if the value is absent, instead of throwing an exception.
* The preferred alternative to this method is {@link #orElseThrow()}.
*
* @return the value described by this {@code OptionalLong}
* @throws NoSuchElementException if no value is present
* @see OptionalLong#isPresent()
*/
public long getAsLong() {
if (!isPresent) {
@ -224,6 +221,21 @@ public final class OptionalLong {
return isPresent ? value : supplier.getAsLong();
}
/**
* If a value is present, returns the value, otherwise throws
* {@code NoSuchElementException}.
*
* @return the value described by this {@code OptionalLong}
* @throws NoSuchElementException if no value is present
* @since 10
*/
public long orElseThrow() {
if (!isPresent) {
throw new NoSuchElementException("No value present");
}
return value;
}
/**
* If a value is present, returns the value, otherwise throws an exception
* produced by the exception supplying function.