java.util.Hashtable.containsKey(Object key)方法实例

http://www.yiibai.com/java/util/ashtable_containskey.html

描述

The containsKey(Object key) method is used to test if the specified object is a key in this hashtable.

声明

Following is the declaration for java.util.Hashtable.containsKey() method.

public boolean containsKey(Object key)

参数

key--This is the a key to be searched.

返回值

The method call returns true if and only if the specified object is a key in this hashtable.

异常

NullPointerException--This is thrown if the key is null.

以下例子将告诉你如何使用 java.util.Hashtable.containsKey()

package yiibai.com;

import java.util.*;

public class HashTableDemo {
public static void main(String args[]) {
// create hash table
Hashtable htable = new Hashtable();

// put values into the table
htable.put(1, "A");
htable.put(2, "B");
htable.put(3, "C");
htable.put(4, "D");

// check if table contains key "3"
boolean isavailable=htable.containsKey(3);

// display search result
System.out.println("Hash table contains key '3': "+isavailable);
}
}

Let us compile and run the above program, this will produce the following result.

Hash table contains key '3': true