？是“任意类”的意思，extends继承不多说，E是指定类型，是泛型;通常出现在将一个集合赋值给另一个集合的情景中，如：public LinkedList(Collection<? extends E> c )、addAll(Collection<? extends E> c)；下面请看代码：//解释***public LinkedList(Collection<? extends E> c )LinkedList<Strin...
？是“任意类”的意思，extends继承不多说，E是指定类型。首先，楼上说的不错，是泛型。这是java 1.5以后引入的。从此以后，定义一个空的ArrayList需要这样，比如我需要一个MyClass的顺序表，则：ArrayList<MyClass> myList = new ArrayList<MyClass>();这是因为ArrayList类的声明是public class Arra...
当然、这一块涉及的知识很广泛、在这里小白只是简单表述 addAll(Collection<? extends E> c) 方法; 回归正题: 这个方法、如图的结果。很好理解,将一个泛型集合添加到另外一个泛型集合当中去、那么当这个目标集合【即:被添加的集合】的元素和添加的集合内的元素发生重复、则不将重复的这个元素添加到目标集合中; 再...
addAll(Collection<? extends E> c)的方法源码 publicclassArrayList<E>extendsAbstractList<E>implementsList<E>,RandomAccess,Cloneable, java.io.Serializable{// 长度为0的空数组privatestaticfinalObject[]EMPTY_ELEMENTDATA= {};// 默认容量为空的数组privatestaticfinalObject[]DEFAULTCAPACITY_EMPTY_ELEMENTDATA= ...
描述(Description) java.util.ArrayList.addAll(Collection《? extends E》 c)方法将指定集合中的所有元素按指定集合的Iterator返回的顺序附加到…
boolean addAll(Collection<? extendsE> c) Adds all of the elements in the specified collection to this collection (optional operation). The behavior of this operation is undefined if the specified collection is modified while the operation is in progress. (This implies that the behavior of this...
Example In the following code shows how to use LinkedHashSet.LinkedHashSet(Collection <? extends E > c) constructor. //fromwww.java2s.comimportjava.util.LinkedHashSet;publicclassMain {publicstaticvoidmain(String[] args) { LinkedHashSet<Integer> lhashSet =newLinkedHashSet<...
public boolean addAll(int index, Collection<? extends E> c) { if (index < 0 || index > size) throw new IndexOutOfBoundsException("Index: "+index+ ", Size: "+size); Object[] a = c.toArray(); int numNew = a.length;
Syntax ArrayList.addAll(Collection <? extends E > c) has the following syntax. publicbooleanaddAll(Collection <?extendsE> c) Example In the following code shows how to use ArrayList.addAll(Collection <? extends E > c) method. /*www.java2s.com*/importjava.util.ArrayList;publicclassMain...