Java.util.ArrayList.addAll(int index, Collection<? extends E> c)方法实例

描述

The java.util.ArrayList.addAll(int index, Collection<? extends E> c) method inserts all of the elements in the specified collection into this list, starting at the specified position. It shifts the element currently at that position (if any) and any subsequent elements to the right (increases their indices). The new elements will appear in the list in the order that they are returned by the specified collection's iterator.

声明

Following is the declaration for java.util.ArrayList.addall(index, c) method

public boolean addAll(int index, Collection<? extends E> c)

参数

• index -- The index at which to insert the first element from the specified collection.

• c -- This is the collection containing elements to be added to this list.

返回值

This method returns true if this list changed as a result of the call.

异常

• IndexOutOfBoundsException -- If the index is out of range

• NullPointerException -- If the specified collection is null

实例一

以下例子将告诉你如何使用 java.util.Arraylist.addall(index, c) method.

package gitbook.net;

import java.util.ArrayList;

public class ArrayListDemo {
  public static void main(String args[]) {

    // create an empty array list1 with an initial capacity
    ArrayList<Integer> arrlist = new ArrayList<Integer>(5);
	
    // use add() method to add elements in the list
    arrlist.add(12);
    arrlist.add(20);
    arrlist.add(45);

    // let us print all the elements available in list1
    System.out.println("Printing list1:");
    for (Integer number : arrlist) {
      System.out.println("Number = " + number);
    }

    // create an empty array list2 with an initial capacity
    ArrayList<Integer> arrlist2 = new ArrayList<Integer>(5);
	
    // use add() method to add elements in list2
    arrlist2.add(25);
    arrlist2.add(30);
    arrlist2.add(31);
    arrlist2.add(35);

    // let us print all the elements available in list2
    System.out.println("Printing list2:");
    for (Integer number : arrlist2) {
      System.out.println("Number = " + number);
    }

    // inserting all elements of list2 at third position
    arrlist.addAll(2, arrlist2);
	
    System.out.println("Printing all the elements");
    // let us print all the elements available in list1
    for (Integer number : arrlist) {
      System.out.println("Number = " + number);
    }
  }
}

编译和执行以上程序，将得到以下的结果：

Printing list1:
Number = 12
Number = 20
Number = 45
Printing list2:
Number = 25
Number = 30
Number = 31
Number = 35
Printing all the elements
Number = 12
Number = 20
Number = 25
Number = 30
Number = 31
Number = 35
Number = 45

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