Basic Java Example program Check if a particular key exists HashMap

Minggu, 13 Maret 2016

1.Basic Java example program to check particular key exists in hashmap

package com.javacheckkeyhashmap;
import java.util.Hashmap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
public class HashmapExample{
public static void main(String[] args) {
//create an Hashmap object
HashMap<String, String> hashmap = new HashMap();
//Add key values pairs to hashmap
hashmap.put("1","One");
hashmap.put("2","Two");
hashmap.put("3","Three");
hashmap.put("4","Four");
hashmap.put("5","Five");
hashmap.put("6","Six");
/*
To check whether a particular key exists in HashMap use
boolean containsKey(Object key) method of HashMap class.
containsKey(Object key) returns true if the HashMap contains mapping for specified key
otherwise false.
*/
boolean isExists = hashmap.containsKey("4");
System.out.println("4 exists in HashMap ? : " + isExists);
if(!hashmap.isEmpty()){
Iterator it=hashmap.entrySet().iterator();
while(it.hasNext()){
Map.Entry obj=(Entry) it.next();
System.out.print(obj.getKey()+" ");
System.out.println(obj.getValue());
}
}
}
}