我正在研究 ArrayList 實現并找到了 forEachRemaining 方法。這個或者什么時候調用這個方法有什么用？public class ArrayList<E> extends AbstractList<E> implements List<E>, RandomAccess, Cloneable, java.io.Serializable{ //... //... private class Itr implements Iterator<E> { //... @Override @SuppressWarnings("unchecked") public void forEachRemaining(Consumer<? super E> consumer) { Objects.requireNonNull(consumer); final int size = ArrayList.this.size; int i = cursor; if (i >= size) { return; } final Object[] elementData = ArrayList.this.elementData; if (i >= elementData.length) { throw new ConcurrentModificationException(); } while (i != size && modCount == expectedModCount) { consumer.accept((E) elementData[i++]); } // update once at end of iteration to reduce heap write traffic cursor = i; lastRet = i - 1; checkForComodification(); } }}
2 回答
幕布斯6054654
TA貢獻1876條經驗 獲得超7個贊
ArrayList沒有forEachRemaining，迭代器等它返回做。
對每個剩余元素執行給定的操作，直到處理完所有元素或操作引發異常。如果指定了該順序，則操作按迭代順序執行。動作拋出的異常被轉發給調用者。
汪汪一只貓
TA貢獻1898條經驗 獲得超8個贊
如果使用迭代器遍歷列表，next()則它將返回該列表中的下一個元素。因此，假設您沒有遍歷完整列表并調用forEachRemaining()它，那么它將列表中未遍歷的剩余元素。
演示
List<String> list = new ArrayList<>();
list.add("one");
list.add("two");
list.add("three");
list.add("four");
list.add("five");
//added five element in list
Iterator<String> iterator = list.iterator();
//visiting two elements by called next()
System.out.println("Printed by next():" + iterator.next());
System.out.println("Printed by next():" + iterator.next());
//remaining un-visited elements can be accessed using forEachRemaining()
iterator.forEachRemaining(s -> {System.out.println( "Printed by forEachRemaining():" + s);});
輸出：
Printed by next():one
Printed by next():two
Printed by forEachRemaining():three
Printed by forEachRemaining():four
Printed by forEachRemaining():five
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