Java.util.ArrayList.clear()

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描述

该java.util.ArrayList.clear()方法移除此调用返回后,所有从这个list.The列表中的元素将是空的。

声明

以下是java.util.ArrayList.clear()方法的声明

public void clear()

参数

NA

返回值

此方法不返回任何值。

异常

NA

实例

以下示例显示了java.util.Arraylist.clear()方法的用法。

package com.tutorialspoint;

import java.util.ArrayList;

public class ArrayListDemo {
   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");
   }
}

让我们编译并运行上面的程序,这将产生以下结果

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