Java教程

Java Vector contains()

Java Vector类的 contains()方法用于检查正在使用的Vector 是否包含指定的元素与否。如果此向量包含指定的元素,则返回true,否则返回false。

语法:

以下是 contains()的声明>方法:
public boolean contains(Object o)

参数:

参数 说明 必需/可选
o 该元素将在此向量中被测试。 必需

返回:

如果此向量包含指定的元素,则 contains()方法返回true,否则返回false。

例外:

NA

兼容版本:

Java 1.2及更高版本

示例1:

import java.util.Vector;
public class VectorContainsExample1 {  
    public static void main(String arg[]) {
        //Create an empty Vector
            Vector<String> vec = new Vector<>();       
            //Add elements to the Vector
            vec.add("Python");
            vec.add("Java");
            vec.add("COBOL");
            vec.add("Ruby"); 
            //Checking if Java is present or not        
            if(vec.contains("Java"))
            {
                 System.out.println("Java is present at the index " +vec.indexOf("Java"));
            }
            else
            {
               System.out.println("Java is not present in the list");
            }
      }            
}
输出:
Java is present at the index 1

示例2:

import java.util.Vector;
public class VectorContainsExample2 {  
    public static void main(String arg[]) {
       //Create an empty Vector
       Vector<Integer>  vec = new Vector<Integer>(4);        
       vec.add(11);
       vec.add(22);
       vec.add(33);
       vec.add(44);
       vec.add(55);
       //Here we check the existence of number 33 in the vector
       System.out.println("Existence: "+vec.contains(33)); 
       }            
}
输出:
Existence: true

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