%uA0java.util.ArrayList.contains(Object)%uA0如果此列表包含指定的元素方法返回true。
声明
以下是java.util.ArrayList.contains()方法的声明
public boolean contains(Object o)
参数
-
o%uA0-- 其存在于该列表用来进行测试的元素。
返回值
如果此列表包含指定的元素,此方法返回true。
异常
-
NA
例子
下面的示例演示java.util.Arraylist.contains方法的用法。
package com.yiibai 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") } } }
让我们来编译和运行上面的程序,这将产生以下结果:
Number = 20 Number = 25 Number = 10 Number = 15 element 10 is contained in the list element 30 is not contained in the list