8050820: Please add java.util.Optional.stream() to convert Optional<T> to Stream<T>
Reviewed-by: alundblad, forax, chegar, jrose
--- a/jdk/src/java.base/share/classes/java/util/Optional.java Mon Feb 02 14:19:00 2015 +0100
+++ b/jdk/src/java.base/share/classes/java/util/Optional.java Mon Feb 02 14:19:12 2015 +0100
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2015, 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
@@ -28,6 +28,7 @@
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.Supplier;
+import java.util.stream.Stream;
/**
* A container object which may or may not contain a non-null value.
@@ -155,8 +156,9 @@
* null
*/
public void ifPresent(Consumer<? super T> consumer) {
- if (value != null)
+ if (value != null) {
consumer.accept(value);
+ }
}
/**
@@ -172,10 +174,11 @@
*/
public Optional<T> filter(Predicate<? super T> predicate) {
Objects.requireNonNull(predicate);
- if (!isPresent())
+ if (!isPresent()) {
return this;
- else
+ } else {
return predicate.test(value) ? this : empty();
+ }
}
/**
@@ -209,9 +212,9 @@
*/
public<U> Optional<U> map(Function<? super T, ? extends U> mapper) {
Objects.requireNonNull(mapper);
- if (!isPresent())
+ if (!isPresent()) {
return empty();
- else {
+ } else {
return Optional.ofNullable(mapper.apply(value));
}
}
@@ -235,14 +238,37 @@
*/
public<U> Optional<U> flatMap(Function<? super T, Optional<U>> mapper) {
Objects.requireNonNull(mapper);
- if (!isPresent())
+ if (!isPresent()) {
return empty();
- else {
+ } else {
return Objects.requireNonNull(mapper.apply(value));
}
}
/**
+ * If a value is present return a sequential {@link Stream} containing only
+ * that value, otherwise return an empty {@code Stream}.
+ *
+ * @apiNote This method can be used to transform a {@code Stream} of
+ * optional elements to a {@code Stream} of present value elements:
+ *
+ * <pre>{@code
+ * Stream<Optional<T>> os = ..
+ * Stream<T> s = os.flatMap(Optional::stream)
+ * }</pre>
+ *
+ * @return the optional value as a {@code Stream}
+ * @since 1.9
+ */
+ public Stream<T> stream() {
+ if (!isPresent()) {
+ return Stream.empty();
+ } else {
+ return Stream.of(value);
+ }
+ }
+
+ /**
* Return the value if present, otherwise return {@code other}.
*
* @param other the value to be returned if there is no value present, may
--- a/jdk/src/java.base/share/classes/java/util/OptionalDouble.java Mon Feb 02 14:19:00 2015 +0100
+++ b/jdk/src/java.base/share/classes/java/util/OptionalDouble.java Mon Feb 02 14:19:12 2015 +0100
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2015, 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
@@ -27,6 +27,7 @@
import java.util.function.DoubleConsumer;
import java.util.function.DoubleSupplier;
import java.util.function.Supplier;
+import java.util.stream.DoubleStream;
/**
* A container object which may or may not contain a {@code double} value.
@@ -138,8 +139,32 @@
* null
*/
public void ifPresent(DoubleConsumer consumer) {
- if (isPresent)
+ if (isPresent) {
consumer.accept(value);
+ }
+ }
+
+ /**
+ * If a value is present return a sequential {@link DoubleStream} containing
+ * only that value, otherwise return an empty {@code DoubleStream}.
+ *
+ * @apiNote This method can be used to transform a {@code Stream} of
+ * optional doubles to a {@code DoubleStream} of present doubles:
+ *
+ * <pre>{@code
+ * Stream<OptionalDouble> os = ..
+ * DoubleStream s = os.flatMapToDouble(OptionalDouble::stream)
+ * }</pre>
+ *
+ * @return the optional value as a {@code DoubleStream}
+ * @since 1.9
+ */
+ public DoubleStream stream() {
+ if (isPresent) {
+ return DoubleStream.of(value);
+ } else {
+ return DoubleStream.empty();
+ }
}
/**
--- a/jdk/src/java.base/share/classes/java/util/OptionalInt.java Mon Feb 02 14:19:00 2015 +0100
+++ b/jdk/src/java.base/share/classes/java/util/OptionalInt.java Mon Feb 02 14:19:12 2015 +0100
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2015, 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
@@ -27,6 +27,7 @@
import java.util.function.IntConsumer;
import java.util.function.IntSupplier;
import java.util.function.Supplier;
+import java.util.stream.IntStream;
/**
* A container object which may or may not contain a {@code int} value.
@@ -138,8 +139,32 @@
* null
*/
public void ifPresent(IntConsumer consumer) {
- if (isPresent)
+ if (isPresent) {
consumer.accept(value);
+ }
+ }
+
+ /**
+ * If a value is present return a sequential {@link IntStream} containing
+ * only that value, otherwise return an empty {@code IntStream}.
+ *
+ * @apiNote This method can be used to transform a {@code Stream} of
+ * optional integers to an {@code IntStream} of present integers:
+ *
+ * <pre>{@code
+ * Stream<OptionalInt> os = ..
+ * IntStream s = os.flatMapToInt(OptionalInt::stream)
+ * }</pre>
+ *
+ * @return the optional value as an {@code IntStream}
+ * @since 1.9
+ */
+ public IntStream stream() {
+ if (isPresent) {
+ return IntStream.of(value);
+ } else {
+ return IntStream.empty();
+ }
}
/**
--- a/jdk/src/java.base/share/classes/java/util/OptionalLong.java Mon Feb 02 14:19:00 2015 +0100
+++ b/jdk/src/java.base/share/classes/java/util/OptionalLong.java Mon Feb 02 14:19:12 2015 +0100
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2015, 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
@@ -27,6 +27,7 @@
import java.util.function.LongConsumer;
import java.util.function.LongSupplier;
import java.util.function.Supplier;
+import java.util.stream.LongStream;
/**
* A container object which may or may not contain a {@code long} value.
@@ -138,8 +139,32 @@
* null
*/
public void ifPresent(LongConsumer consumer) {
- if (isPresent)
+ if (isPresent) {
consumer.accept(value);
+ }
+ }
+
+ /**
+ * If a value is present return a sequential {@link LongStream} containing
+ * only that value, otherwise return an empty {@code LongStream}.
+ *
+ * @apiNote This method can be used to transform a {@code Stream} of
+ * optional longs to a {@code LongStream} of present longs:
+ *
+ * <pre>{@code
+ * Stream<OptionalLong> os = ..
+ * LongStream s = os.flatMapToLong(OptionalLong::stream)
+ * }</pre>
+ *
+ * @return the optional value as a {@code LongStream}
+ * @since 1.9
+ */
+ public LongStream stream() {
+ if (isPresent) {
+ return LongStream.of(value);
+ } else {
+ return LongStream.empty();
+ }
}
/**
--- a/jdk/test/java/util/Optional/Basic.java Mon Feb 02 14:19:00 2015 +0100
+++ b/jdk/test/java/util/Optional/Basic.java Mon Feb 02 14:19:12 2015 +0100
@@ -29,6 +29,7 @@
import java.util.NoSuchElementException;
import java.util.Optional;
+import java.util.stream.Stream;
import static org.testng.Assert.*;
import org.testng.annotations.Test;
@@ -54,8 +55,8 @@
assertSame(null, empty.orElse(null));
RuntimeException orElse = new RuntimeException() { };
assertSame(Boolean.FALSE, empty.orElse(Boolean.FALSE));
- assertSame(null, empty.orElseGet(()-> null));
- assertSame(Boolean.FALSE, empty.orElseGet(()-> Boolean.FALSE));
+ assertSame(null, empty.orElseGet(() -> null));
+ assertSame(Boolean.FALSE, empty.orElseGet(() -> Boolean.FALSE));
}
@Test(expectedExceptions=NoSuchElementException.class)
@@ -104,15 +105,15 @@
try {
present.ifPresent(v -> { throw new ObscureException(); });
fail();
- } catch(ObscureException expected) {
+ } catch (ObscureException expected) {
}
assertSame(Boolean.TRUE, present.orElse(null));
assertSame(Boolean.TRUE, present.orElse(Boolean.FALSE));
assertSame(Boolean.TRUE, present.orElseGet(null));
- assertSame(Boolean.TRUE, present.orElseGet(()-> null));
- assertSame(Boolean.TRUE, present.orElseGet(()-> Boolean.FALSE));
- assertSame(Boolean.TRUE, present.<RuntimeException>orElseThrow( null));
+ assertSame(Boolean.TRUE, present.orElseGet(() -> null));
+ assertSame(Boolean.TRUE, present.orElseGet(() -> Boolean.FALSE));
+ assertSame(Boolean.TRUE, present.<RuntimeException>orElseThrow(null));
assertSame(Boolean.TRUE, present.<RuntimeException>orElseThrow(ObscureException::new));
}
@@ -226,6 +227,26 @@
assertSame(l, fixture);
}
+ @Test(groups = "unit")
+ public void testStream() {
+ {
+ Stream<String> s = Optional.<String>empty().stream();
+ assertFalse(s.isParallel());
+
+ Object[] es = s.toArray();
+ assertEquals(es.length, 0);
+ }
+
+ {
+ Stream<String> s = Optional.of("Duke").stream();
+ assertFalse(s.isParallel());
+
+ String[] es = s.toArray(String[]::new);
+ assertEquals(es.length, 1);
+ assertEquals(es[0], "Duke");
+ }
+ }
+
private static class ObscureException extends RuntimeException {
}
--- a/jdk/test/java/util/Optional/BasicDouble.java Mon Feb 02 14:19:00 2015 +0100
+++ b/jdk/test/java/util/Optional/BasicDouble.java Mon Feb 02 14:19:12 2015 +0100
@@ -29,6 +29,7 @@
import java.util.NoSuchElementException;
import java.util.OptionalDouble;
+import java.util.stream.DoubleStream;
import static org.testng.Assert.*;
import org.testng.annotations.Test;
@@ -109,6 +110,26 @@
assertEquals(1.0, present.<RuntimeException>orElseThrow(ObscureException::new));
}
+ @Test(groups = "unit")
+ public void testStream() {
+ {
+ DoubleStream s = OptionalDouble.empty().stream();
+ assertFalse(s.isParallel());
+
+ double[] es = s.toArray();
+ assertEquals(es.length, 0);
+ }
+
+ {
+ DoubleStream s = OptionalDouble.of(42.0).stream();
+ assertFalse(s.isParallel());
+
+ double[] es = s.toArray();
+ assertEquals(es.length, 1);
+ assertEquals(es[0], 42.0);
+ }
+ }
+
private static class ObscureException extends RuntimeException {
}
--- a/jdk/test/java/util/Optional/BasicInt.java Mon Feb 02 14:19:00 2015 +0100
+++ b/jdk/test/java/util/Optional/BasicInt.java Mon Feb 02 14:19:12 2015 +0100
@@ -29,6 +29,7 @@
import java.util.NoSuchElementException;
import java.util.OptionalInt;
+import java.util.stream.IntStream;
import static org.testng.Assert.*;
import org.testng.annotations.Test;
@@ -53,36 +54,36 @@
assertEquals(2, empty.orElseGet(()-> 2));
}
- @Test(expectedExceptions=NoSuchElementException.class)
- public void testEmptyGet() {
- OptionalInt empty = OptionalInt.empty();
+ @Test(expectedExceptions=NoSuchElementException.class)
+ public void testEmptyGet() {
+ OptionalInt empty = OptionalInt.empty();
- int got = empty.getAsInt();
- }
+ int got = empty.getAsInt();
+ }
- @Test(expectedExceptions=NullPointerException.class)
- public void testEmptyOrElseGetNull() {
- OptionalInt empty = OptionalInt.empty();
+ @Test(expectedExceptions=NullPointerException.class)
+ public void testEmptyOrElseGetNull() {
+ OptionalInt empty = OptionalInt.empty();
- int got = empty.orElseGet(null);
- }
+ int got = empty.orElseGet(null);
+ }
- @Test(expectedExceptions=NullPointerException.class)
- public void testEmptyOrElseThrowNull() throws Throwable {
- OptionalInt empty = OptionalInt.empty();
+ @Test(expectedExceptions=NullPointerException.class)
+ public void testEmptyOrElseThrowNull() throws Throwable {
+ OptionalInt empty = OptionalInt.empty();
- int got = empty.orElseThrow(null);
- }
+ int got = empty.orElseThrow(null);
+ }
- @Test(expectedExceptions=ObscureException.class)
- public void testEmptyOrElseThrow() throws Exception {
- OptionalInt empty = OptionalInt.empty();
+ @Test(expectedExceptions=ObscureException.class)
+ public void testEmptyOrElseThrow() throws Exception {
+ OptionalInt empty = OptionalInt.empty();
- int got = empty.orElseThrow(ObscureException::new);
- }
+ int got = empty.orElseThrow(ObscureException::new);
+ }
- @Test(groups = "unit")
- public void testPresent() {
+ @Test(groups = "unit")
+ public void testPresent() {
OptionalInt empty = OptionalInt.empty();
OptionalInt present = OptionalInt.of(1);
@@ -109,6 +110,26 @@
assertEquals(1, present.<RuntimeException>orElseThrow(ObscureException::new));
}
+ @Test(groups = "unit")
+ public void testStream() {
+ {
+ IntStream s = OptionalInt.empty().stream();
+ assertFalse(s.isParallel());
+
+ int[] es = s.toArray();
+ assertEquals(es.length, 0);
+ }
+
+ {
+ IntStream s = OptionalInt.of(42).stream();
+ assertFalse(s.isParallel());
+
+ int[] es = OptionalInt.of(42).stream().toArray();
+ assertEquals(es.length, 1);
+ assertEquals(es[0], 42);
+ }
+ }
+
private static class ObscureException extends RuntimeException {
}
--- a/jdk/test/java/util/Optional/BasicLong.java Mon Feb 02 14:19:00 2015 +0100
+++ b/jdk/test/java/util/Optional/BasicLong.java Mon Feb 02 14:19:12 2015 +0100
@@ -29,6 +29,7 @@
import java.util.NoSuchElementException;
import java.util.OptionalLong;
+import java.util.stream.LongStream;
import static org.testng.Assert.*;
import org.testng.annotations.Test;
@@ -109,6 +110,24 @@
assertEquals(1, present.<RuntimeException>orElseThrow(ObscureException::new));
}
+ @Test(groups = "unit")
+ public void testStream() {
+ {
+ LongStream s = OptionalLong.empty().stream();
+
+ long[] es = s.toArray();
+ assertEquals(es.length, 0);
+ }
+
+ {
+ LongStream s = OptionalLong.of(42L).stream();
+
+ long[] es = s.toArray();
+ assertEquals(es.length, 1);
+ assertEquals(es[0], 42L);
+ }
+ }
+
private static class ObscureException extends RuntimeException {
}