JDK1.8中新增的特性:
1. void forEach(Consumer<? super E> action)
:JDK8中新特性,對list中每個元素分別進行操作,如:
ArrayList<Integer> al = new ArrayList<>();
al.add(0);
al.add(1);
al.add(2);
al.add(3);
al.forEach(line -> System.out.println(line));
2.Spliterator<E> spliterator()
:返回一個並行迭代器
return new ArrayListSpliterator<>(this, 0, -1, 0);
示例如下:
ArrayList<String> a1 = new ArrayList<String>();
a1.add("asd");
a1.add("zxc");
a1.add("xfgj");
a1.add("asd");
Spliterator<String> spliterator = a1.spliterator();
spliterator.forEachRemaining(ele -> System.out.print(ele + " "));
結果如下:
asd zxc xfgj asd
3.boolean removeIf(Predicate<? super E> filter)
:移除集合中滿足給定條件的所有元素。filter是令元素移除成功的條件過濾器,示例如下:
ArrayList<String> a1 = new ArrayList<String>();
a1.add("asd");
a1.add("zxc");
a1.add("xfgj");
a1.add("adsw");
a1.forEach(element -> System.out.print(element + " "));
System.out.println();
a1.removeIf(element -> element.startsWith("a"));// 過濾掉以"a"開頭的元素
a1.forEach(element -> System.out.print(element + " "));
System.out.println();
Predicate<String> predicate = (element) -> element.contains("j"); // 這裏單獨定義了過濾器
a1.removeIf(predicate); // 過濾掉包含"j"的元素
a1.forEach(line -> System.out.println(line)); // 輸出 zxc
4.void replaceAll(UnaryOperator<E> operator)
:替換list中的元素
Objects.requireNonNull(operator);
final int expectedModCount = modCount;
final int size = this.size;
for (int i=0; modCount == expectedModCount && i < size; i++) {
elementData[i] = operator.apply((E) elementData[i]);
}
if (modCount != expectedModCount) {
throw new ConcurrentModificationException();
}
modCount++;
示例如下:
ArrayList<String> a1 = new ArrayList<String>();
a1.add("asd");
a1.add("zxc");
a1.add("xfgj");
a1.add("asd");
a1.replaceAll(element -> element.contains("a")?"111": "000");
a1.forEach(elemet -> System.out.print(elemet + " "));
輸出結果如下:
111 000 000 111
5.void sort(Comparator<? super E> c)
:用於list集合排序,使用了Comparator比較器來比較,實現裏面的compare方法,compareTo比較之後,返回的參數是int類型,0則表示相等,1表示大於,-1負數則表示小於。
@Override
@SuppressWarnings("unchecked")
public void sort(Comparator<? super E> c) {
final int expectedModCount = modCount;
Arrays.sort((E[]) elementData, 0, size, c);
if (modCount != expectedModCount) {
throw new ConcurrentModificationException();
}
modCount++;
}
示例如下:
ArrayList<String> a1 = new ArrayList<String>();
a1.add("asd");
a1.add("zxc");
a1.add("xfgj");
a1.add("adsw");
a1.sort(new Comparator<String>() {
@Override
public int compare(String o1, String o2) {
return o1.compareTo(o2);
}
});
a1.forEach(line -> System.out.print(line + " "));