1.Basic java example program to check particular element is exists in hashset

• boolean contains(Object o)   This method Returns true if this set contains the specified element

1. package com.checkelementhashset;
2.  
3. import java.util.HashSet;
4. import java.util.Iterator;
5.  
6. public class HashsetExample{
7.  
8. public static void main(String[] args) {
9.   
10. //create object of HashSet
11.  HashSet<Integer> hashSet = new HashSet();
12.        
13.  //add elements to HashSet object
14.  hashSet.add(1);
15.  hashSet.add(2);
16.  hashSet.add(3);
17.  hashSet.add(4);
18.  hashSet.add(5);
19.      
20.  /*
21.  To check whether a particular value exists in HashSetwe need to use
22.   boolean contains(Object value) method of HashSet class.
23.  this method returns true if the HashSet contains the value, otherwise returns false.
24.  */
25.        
26.         boolean isExists = hashSet.contains(5);
27.         System.out.println("5 exists in HashSet ? : " + isExists);    
28.  
29. 
    
30.  
31. Iterator it=hashSet.iterator();
32.              
33. while(it.hasNext()){
34. System.out.println(it.next());
35.                      
36. }   
37.  
38. }
39.  
40. }
     

Output:

1. 3 exists in HashSet ? : true
2. 1
3. 2
4. 3
5. 4
6. 5

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

1. package com.javacheckkeyhashmap;
2.  
3. import java.util.Hashmap;
4. import java.util.Iterator;
5. import java.util.Map;
6. import java.util.Map.Entry;
7.  
8. public class HashmapExample{
9.  
10. public static void main(String[] args) {
11.   
12. //create an Hashmap object
13. HashMap<String, String> hashmap = new HashMap();
14.        
15. //Add key values pairs to hashmap
16.         
17. hashmap.put("1","One");
18. hashmap.put("2","Two");
19. hashmap.put("3","Three");
20. hashmap.put("4","Four");
21. hashmap.put("5","Five");
22. hashmap.put("6","Six");       
23.         
24.  
25.  /*
26.   To check whether a particular key exists in HashMap use
27.    boolean containsKey(Object key) method of HashMap class.
28.   containsKey(Object key) returns true if the HashMap contains mapping for specified key
29.   otherwise false.
30.  */
31.  
32. boolean isExists = hashmap.containsKey("4");
33. System.out.println("4 exists in HashMap ? : " + isExists);
34.     
35.  
36. if(!hashmap.isEmpty()){
37.  
38. Iterator it=hashmap.entrySet().iterator();
39.              
40. while(it.hasNext()){
41. 
    
42. Map.Entry obj=(Entry) it.next();
43. System.out.print(obj.getKey()+" ");
44. System.out.println(obj.getValue());
45.              
46. }           
47. }   
48.  
49. }
50.  
51. }
     

Output:

1. 4 exists in HashMap ? : true
2. 1 One
3. 2 Two
4. 3 Three
5. 4 Four
6. 5 Five
7. 6 Six