1.Basic java example program to iterate keys of hashtable

• Enumeration keys()   This method used to get keys of hashmap
  

1. package com.iteartekeysHashtable;
2.  
3. import java.util.Hashtable;
4. 
   
5. import java.util.Enumeration;
6.  
7. public class HashtableExample{
8.  
9. public static void main(String[] args) {
10.   
11.  //create Hashtable object
12.        Hashtable<String,String> hashtable = new Hashtable<String,String>();
13.        
14. //add key value pairs to Hashtable
15. hashtable.put("1","Java Interview Questions");
16. hashtable.put("2","Java Interview Programs");
17. hashtable.put("3","Concept and exampe program");
18. hashtable.put("4","Concept and interview Questions");
19. hashtable.put("5","Java Quiz");
20. hashtable.put("6","Real time examples");
21.  
22.  
23.  
24. Enumeration e=hashtable.keys();
25.           
26.  
27.            
28. // display search result
29.  while (e.hasMoreElements()) {
30.         System.out.println(e.nextElement());
31. }    
32. 
    
33. }
34.  
35. }
     

Output:

1. 6
2. 5
3. 4
4. 3
5. 2
6. 1

1.Basic java example program to check particular value exist in hashtable

• boolean contains(Object value)   This method used to check  particular value exist in hashtable

1. package com.CheckElelemtHashtable;
2.  
3. import java.util.Hashtable;
4. 
   
5. import java.util.Enumeration;
6.  
7. public class HashtableExample{
8.  
9. public static void main(String[] args) {
10.   
11.  //create Hashtable object
12.        Hashtable<String,String> hashtable = new Hashtable<String,String>();
13.        
14. //add key value pairs to Hashtable
15. hashtable.put("1","Java Interview Questions");
16. hashtable.put("2","Java Interview Programs");
17. hashtable.put("3","Concept and exampe program");
18. hashtable.put("4","Concept and interview Questions");
19. hashtable.put("5","Java Quiz");
20. hashtable.put("6","Real time examples");
21.  
22.  /*
23.  To check whether a particular value exists in Hashtable we need to use
24.  boolean containsKey(Object value) method of Hashtable class.
25. if the Hashtable contains mapping for specified value It returns true
26. otherwise returns false.
27. */
28.        
29.  boolean isExists = hashtable.contains("Java Quiz");
30.  System.out.println("Java Quiz exists in Hashtable ? : " + isExists);
31. 
    
32. System.out.println("Hashtable values : ");
33.  
34. Enumeration e=hashtable.elements();
35.           
36.  
37.            
38. // display search result
39.  while (e.hasMoreElements()) {
40.         System.out.println(e.nextElement());
41. }    
42. 
    
43. }
44.  
45. }
     

Output:

1. Java Quiz exists in Hashtable ? : true
2. Hashtable values : 
3. Real time examples
4. Java Quiz
5. Concept and interview Questions
6. Concept and exampe program
7. Java Interview Programs
8. Java Interview Questions

1.Basic java example program to check particular element exist in hashtable.

• boolean containsKey(Object key)   This method used to check  particular key exist in hashtable

1. package com.CheckElelemtHashtable;
2.  
3. import java.util.Hashtable;
4. import java.util.Iterator;
5.  
6. public class HashtableExample{
7.  
8. public static void main(String[] args) {
9.   
10.  //create Hashtable object
11.        Hashtable<String,String> hashtable = new Hashtable<String,String>();
12.        
13. //add key value pairs to Hashtable
14. hashtable.put("1","Java Interview Questions");
15. hashtable.put("2","Java Interview Programs");
16. hashtable.put("3","Concept and exampe program");
17. hashtable.put("4","Concept and interview Questions");
18. hashtable.put("5","Java Quiz");
19. hashtable.put("6","Real time examples");
20.  
21.  /*
22.  To check whether a particular key exists in Hashtable we need to use
23.  boolean containsKey(Object key) method of Hashtable class.
24. if the Hashtable contains mapping for specified key It returns true
25. otherwise returns false.
26. */
27.        
28.  boolean isExists = hashtable.containsKey("5");
29.  System.out.println("5 exists in Hashtable ? : " + isExists);
30. 
    
31.  
32.  
33. Enumeration e=hashtable.elements();
34.           
35.  System.out.println("Display result:"); 
36.            
37. // display search result
38.  while (e.hasMoreElements()) {
39.         System.out.println(e.nextElement());
40. }    
41. 
    
42. }
43.  
44. }
     

Output:

1. 5 exists in Hashtable ? : true
2. Hashtable values : 
3. Display result:
4. Real time examples
5. Java Quiz
6. Concept and interview Questions
7. Concept and exampe program
8. Java Interview Programs
9. Java Interview Questions

1.Basic java example program to remove all elements in linkedhashset

• clear()   This method used to remove all elements from Linkedhashset.

1. package com.removeelementLinkedhashset;
2.  
3. import java.util.LinkedHashSet;
4. import java.util.Iterator;
5.  
6. public class LinkedHashsetExample{
7.  
8. public static void main(String[] args) {
9.   
10. LinkedHashSet<String> linkedhashset = new LinkedHashSet<>();
11.        
12.         linkedhashset.add("Java Interview Questions");
13.         linkedhashset.add("Java interview program");
14.         linkedhashset.add("Concept and example program");
15.         linkedhashset.add("Concept and interview questions");
16.         linkedhashset.add("Java Quiz");
17.     
18.       
19. System.out.println("LinkedHashSet before removal : " + linkedhashset);
20.  
21.   boolean blnRemoved = linkedhashset.remove("Java Quiz");
22.   System.out.println("Was Java Quiz removed from LinkedHashSet ? " + blnRemoved);
23.   
24. 
    
25.  
26. System.out.println("LinkedHashSet after removal : ");
27.  
28. Iterator it=linkedhashset.iterator();
29.              
30. while(it.hasNext()){
31. System.out.println(it.next());
32.                      
33. }   
34.  linkedhashset.clear();
35.  System.out.println("LinkedHashSet after removal  all elements"); 
36.  
37. }
38.  
39. }
     

Output:

1. LinkedHashSet before removal : [Java Interview Questions, Java interview program, Concept
2. and example program, Concept and interview questions, Java Quiz]
3. Was Java Quiz removed from LinkedHashSet ? true
4. LinkedHashSet after removal :
5. Java Interview Questions
6. Java interview program
7. Concept and example program
8. Concept and interview questions
9. LinkedHashSet after removal all elements  :[]

1.Basic java example program to remove particular element in linkedhashset

• boolean remove(Object o)    This method used to remove specified element from Linkedhashset.

1. package com.removeelementLinkedhashset;
2.  
3. import java.util.LinkedHashSet;
4. import java.util.Iterator;
5.  
6. public class LinkedHashsetExample{
7.  
8. public static void main(String[] args) {
9.   
10. LinkedHashSet<String> linkedhashset = new LinkedHashSet<>();
11.        
12.         linkedhashset.add("Java Interview Questions");
13.         linkedhashset.add("Java interview program");
14.         linkedhashset.add("Concept and example program");
15.         linkedhashset.add("Concept and interview questions");
16.         linkedhashset.add("Java Quiz");
17.     
18.       
19. System.out.println("LinkedHashSet before removal : " + linkedhashset);
20.  
21.   boolean blnRemoved = linkedhashset.remove("Java Quiz");
22.   System.out.println("Was Java Quiz removed from LinkedHashSet ? " + blnRemoved);
23.   
24. 
    
25.  
26. System.out.println("LinkedHashSet after removal : ");
27.  
28. Iterator it=linkedhashset.iterator();
29.              
30. while(it.hasNext()){
31. System.out.println(it.next());
32.                      
33. }   
34.  
35. }
36.  
37. }
     

Output:

1. LinkedHashSet before removal : [Java Interview Questions, Java interview program, Concept
2. and example program, Concept and interview questions, Java Quiz]
3. Was Java Quiz removed from LinkedHashSet ? true
4. Java Interview Questions
5. Java interview program
6. Concept and example program
7. Concept and interview questions