getFirst and getLast on Iterable (original) (raw)
Otávio Gonçalves de Santana otaviopolianasantana at gmail.com
Thu Apr 17 04:30:31 UTC 2014
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I would to add for news methods on Iterable, I believe it will helpful for many Java Developers.
diff -r 3dd165facde7 test/java/util/Iterator/IteratorDefaults.java
--- a/test/java/util/Iterator/IteratorDefaults.java Wed Apr 09 12:26:00 2014 -0700
+++ b/test/java/util/Iterator/IteratorDefaults.java Wed Apr 16 23:25:56 2014 -0300
@@ -399,6 +399,48 @@
}
}public void testgetFirst() {List<Integer> source = Arrays.asList(1, 2, 3, 4);int first = source.getFirst();assertEquals(first, 1);List<String> emptySource = Collections.<String>emptyList();assertNull(emptySource.getFirst());}
public void testgetFirstWithDefaultElement() {
List<Integer> source = Arrays.asList(1, 2, 3, 4);Integer defaultElement = 5;assertEquals(source.getFirst(defaultElement), Integer.valueOf(1));List<Integer> emptySource = Collections.<Integer>emptyList();assertEquals(emptySource.getFirst(defaultElement), defaultElement);}
public void testgetLast() {
List<Integer> source = Arrays.asList(1, 2, 3, 4);int last = source.getLast();assertEquals(last, 4);List<String> emptySource = Collections.<String>emptyList();assertNull(emptySource.getLast());}
public void testgetLastWithDefaultElement() {
List<Integer> source = Arrays.asList(1, 2, 3, 4);Integer defaultElement = 5;assertEquals(source.getLast(defaultElement), Integer.valueOf(4));List<Integer> emptySource = Collections.<Integer>emptyList();assertEquals(emptySource.getLast(defaultElement), defaultElement);}
static class IteratorWithRemove implements Iterator {
public boolean removed;diff -r 3dd165facde7 src/share/classes/java/lang/Iterable.java
--- a/src/share/classes/java/lang/Iterable.java Wed Apr 09 12:26:00 2014 -0700
+++ b/src/share/classes/java/lang/Iterable.java Wed Apr 16 23:16:21 2014 -0300
@@ -100,4 +100,55 @@
default Spliterator<T> spliterator() {
return Spliterators.spliteratorUnknownSize(iterator(), 0);
}/**
* returns the first element, if empty will return {@code null}* @return the first element or {@code null}* @since 1.8*/default T getFirst() {
return getFirst(null);}
/**
* returns the first element, if empty will return the default* @param defaultValue - the default value to return if the iterable
is empty
* @return the first element or default element* @since 1.8*/default T getFirst(T defaultValue) {
for (T element : this) {return element;}return defaultValue;}
/**
* returns the last element, if empty will return {@code null}* @return the first element or {@code null}* @since 1.8*/default T getLast() {
return getLast(null);}
/**
* returns the last element, if empty will return the default* @param defaultValue - the default value to return if the iterable
is empty
* @return the last element or default element* @since 1.8*/default T getLast(T defaultValue) {
T last = null;for (T element : this) {last = element;}if (Objects.isNull(last)) {return defaultValue;}return last;}
}
-- Atenciosamente.
Otávio Gonçalves de Santana
blog: http://otaviosantana.blogspot.com.br/ twitter: http://twitter.com/otaviojava site: http://www.otaviojava.com.br (11) 98255-3513
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