Java ArrayList clear()方法

java.util.ArrayList.clear() 用于移除ArrayList的所有元素。

1 语法

public void clear()

2 参数

无

3 返回值

无

4 示例 

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 *java.util.ArrayList.clear()方法的例子
 */
import java.util.ArrayList;

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

        // create an empty array list with an initial capacity
        ArrayList<Integer> arrlist = new ArrayList<Integer>(5);

        // use add() method to add elements in the list
        arrlist.add(20);
        arrlist.add(30);
        arrlist.add(10);
        arrlist.add(50);

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

        // finding size of this list
        int retval = arrlist.size();
        System.out.println("List consists of "+ retval +" elements");

        System.out.println("Performing clear operation !!");
        arrlist.clear();
        retval = arrlist.size();
        System.out.println("Now, list consists of "+ retval +" elements");
    }
}

输出结果为：

Number = 20
Number = 30
Number = 10
Number = 50
List consists of 4 elements
Performing clear operation !!
Now, list consists of 0 elements