java.util.ArrayList.contains(Object) method

描述


The java.util.ArrayList.contains(Object) method returns true if this list contains the specified element.


声明


Following is the declaration for java.util.ArrayList.contains() method


public boolean contains(Object o)
参数


o -- The element whose presence in this list is to be tested.


返回值


This method returns true if this list contains the specified element.


异常


NA




 
实例一编辑+分享实例
以下例子将告诉你如何使用 java.util.Arraylist.contains method.


package yiibai.com;


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<(8);


      // use add() method to add elements in the list
      arrlist.add(20);
      arrlist.add(25);
      arrlist.add(10);
      arrlist.add(15);        
       
      // let us print all the elements available in list
      for (Integer number : arrlist) {
         System.out.println("Number = " + number);
       }


      // list contains element 10
      boolean retval = arrlist.contains(10); 
 
      if (retval == true) {
        System.out.println("element 10 is contained in the list");
       }
      else {
        System.out.println("element 10 is not contained in the list");
       }

      // list does not contain element 30
      boolean retval2 = arrlist.contains(30);
 
      if (retval2 == true) {
        System.out.println("element 30 is contained in the list");
       }
      else {
        System.out.println("element 30 is not contained in the list");    
       }
   }
}
编译和执行以上程序，将得到以下的结果：


Number = 20
Number = 25
Number = 10
Number = 15
element 10 is contained in the list
element 30 is not contained in the list