Get collection values from hashtable example

Posted by: Instanceofjava Posted date: March 17, 2016 / comment : 0 ,

1.Basic java collection framework example program to get Value collection from hashtable

  •   Collection values()   This method used to get collection of values
  •  Important note is that if any value is removed from set the original hashtable key also removed
  1. package com.setviewHashtable;
  2.  
  3. import java.util.Hashtable;

  5. import java.util.Enumeration;
  6. import java.util.Iterator;
  7. import java.util.Set;
  8.  
  9. public class HashtableExample{
  10.  
  11. public static void main(String[] args) {
  12.   
  13.  //create Hashtable object
  14.        Hashtable<String,String> hashtable = new Hashtable<String,String>();
  15.        
  16. //add key value pairs to Hashtable
  17. hashtable.put("1","Java Interview Questions");
  18. hashtable.put("2","Java Interview Programs");
  19. hashtable.put("3","Concept and example program");
  20. hashtable.put("4","Concept and interview Questions");
  21. hashtable.put("5","Java Quiz");
  22. hashtable.put("6","Real time examples");
  23.  
  24.  
  25.  Collection c = hashtable.values();
  26.  System.out.println("Values of Collection created from Hashtable are :");
  27. //iterate through the Set of keys
  28.  
  29.  Iterator itr = c.iterator();
  30.  while(itr.hasNext())
  31.  System.out.println(itr.next());
  32.            
  33.  c.remove("Java Quiz");
  34.            
  35. System.out.println("Elements in hash table");
  36. Enumeration e=hashtable.elements();
  37.         
  38.  
  39.  while (e.hasMoreElements()) {
  40.         System.out.println(e.nextElement());
  41. }    

  43. }
  44.  
  45. }
     



Output:

  1. Values of Collection created from Hashtable are :
  2. Real time examples
  3. Java Quiz
  4. Concept and interview Questions
  5. Concept and example program
  6. Java Interview Programs
  7. Java Interview Questions
  8. Elements in hash table
  9. Real time examples
  10. Concept and interview Questions
  11. Concept and example program
  12. Java Interview Programs
  13. Java Interview Questions


Java Collections example program Get Set view of Keys from Hashtable example

Posted by: Instanceofjava Posted date: March 17, 2016 / comment : 0 ,

1.Basic java collection framework example program to get set view from hashtable

  • Set keySet()   This method used to get set view of the keys of hashtable
  •  Important note is that if any key is removed from set the original hashtable key also removed
  1. package com.setviewHashtable;
  2.  
  3. import java.util.Hashtable;

  5. import java.util.Enumeration;
  6. import java.util.Iterator;
  7. import java.util.Set;
  8.  
  9. public class HashtableExample{
  10.  
  11. public static void main(String[] args) {
  12.   
  13.  //create Hashtable object
  14.        Hashtable<String,String> hashtable = new Hashtable<String,String>();
  15.        
  16. //add key value pairs to Hashtable
  17. hashtable.put("1","Java Interview Questions");
  18. hashtable.put("2","Java Interview Programs");
  19. hashtable.put("3","Concept and example program");
  20. hashtable.put("4","Concept and interview Questions");
  21. hashtable.put("5","Java Quiz");
  22. hashtable.put("6","Real time examples");
  23.  
  24.  
  25.  Set st = hashtable.keySet();       
  26.  System.out.println("Set created from Hashtable Keys contains :");
  27. //iterate through the Set of keys
  28.  
  29.  Iterator itr = st.iterator();
  30.  while(itr.hasNext())
  31.  System.out.println(itr.next());
  32.            
  33.  st.remove("1");
  34.            
  35. System.out.println("Elements in hash table");
  36. Enumeration e=hashtable.keys();
  37.         
  38.  
  39.  while (e.hasMoreElements()) {
  40.         System.out.println(e.nextElement());
  41. }    

  43. }
  44.  
  45. }
     



Output:

  1. Set created from Hashtable Keys contains :
  2. 6
  3. 5
  4. 4
  5. 3
  6. 2
  7. 1
  8. Elements in hash table
  9. 6
  10. 5
  11. 4
  12. 3
  13. 2

Java collections interview programming questions

Posted by: Instanceofjava Posted date: March 16, 2016 / comment : 0

java collections interview programs


Top 100 Java Programs asked in Interviews
  1. Introduction to Collection Framework  

  2. Collection Interface in Java 
  3. Top 20 collection framework interview questions for freshers and experienced

Collection set interface: 

  1. Collection Set Interface    

Hashset Class in Collection framework: (Java programming questions)

  1. Hashset class in java  
  2.  
  4.  
  5.  

LinkedHashSet Class in Collection framework: (Java programming questions)

  2.  

Treeset Class in Collection framework: (Java programming questions)
 
  1.  
  4.  

 Collection List Interface:

  1. Collection List Interface 

ArrayList Class in Collection framework: (Java programming questions)

  1.    
  2.  
  4.  
  5.  
  11. Top 100 Java Programs asked in Interviews 

Map Interface In java

  1. Map interface  

HashMap Class in Collection framework: (Java programming questions)

  1.  
  2.  
  5. Convert keys of a map to List 
  6. Convert Values of a map to List 

 Hashtable Class in Collection framework: (Java interview programming questions)

  3.  
  5.  
  6.  
  8. Top 100 Java Programs asked in Interviews  

Java collections programming interview questions 

  1. Top 20 collection framework interview questions for freshers and experienced  
  2. Collection vs Collections
  3. Difference between enumeration and iterator and list iterator? 
  4. Difference between arraylist and vector 
  5. Differences between HashMap and Hash-table  
  6. Comparable vs Comparator 
  7. Custom iterator in java   
  9. Top 100 Java Programs asked in Interviews 

Remove all elements from hashtable java example

Posted by: Instanceofjava Posted date: March 16, 2016 / comment : 0 ,

1.Basic java example program to remove all elements from hashtable
  • Object remove(Object key)    This method used to remove value pair from hashtable
  • void clear() this method removes all elements from hashtable
  •  
  1. package com.removevalueHashtable;
  2.  
  3. import java.util.Hashtable;

  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 example program");
  18. hashtable.put("4","Concept and interview Questions");
  19. hashtable.put("5","Java Quiz");
  20. hashtable.put("6","Real time examples");
  21.  
  22. Object obj = ht.remove("2");
  23. System.out.println(obj + " Removed from Hashtable");
  24.  
  25. Enumeration e=hashtable.elements();
  26.           
  27.  
  28.  while (e.hasMoreElements()) {
  29.         System.out.println(e.nextElement());
  30. }    
  31. hashtable.clear();
  32.  
  33.  System.out.println("Total key value pairs in Hashtable are : " + hashtable.size());

  35. }
  36.  
  37. }
     



Output:

  1. Java Interview Programs Removed from Hashtable
  2. Real time examples
  3. Java Quiz
  4. Concept and interview Questions
  5. Concept and exampe program
  6. Java Interview Questions
  7. Total key value pairs in Hashtable are : 0

Remove key value pair from hashtable java example

Posted by: Instanceofjava Posted date: March 16, 2016 / comment : 0 ,

1.Basic java example program to iterate keys of hashtable
  • Object remove(Object key)    This method used to remove value pair from hashtable
  1. package com.removevalueHashtable;
  2.  
  3. import java.util.Hashtable;

  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 example program");
  18. hashtable.put("4","Concept and interview Questions");
  19. hashtable.put("5","Java Quiz");
  20. hashtable.put("6","Real time examples");
  21.  
  22. Object obj = ht.remove("2");
  23. System.out.println(obj + " Removed from Hashtable");
  24.  
  25. Enumeration e=hashtable.elements();
  26.           
  27.  
  28.            
  29. // display search result
  30.  while (e.hasMoreElements()) {
  31.         System.out.println(e.nextElement());
  32. }    

  34. }
  35.  
  36. }
     



Output:

  1. Java Interview Programs Removed from Hashtable
  2. Real time examples
  3. Java Quiz
  4. Concept and interview Questions
  5. Concept and exampe program
  6. Java Interview Questions

Iterate through values of hashtable java

Posted by: Instanceofjava Posted date: March 16, 2016 / comment : 0 ,

1.Basic java example program to iterate keys of hashtable
  • Enumeration elements()   This method used to get values of hashmap

  1. package com.iteartekeysHashtable;
  2.  
  3. import java.util.Hashtable;

  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 example 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.elements();
  25.           
  26.  
  27.            
  28. // display search result
  29.  while (e.hasMoreElements()) {
  30.         System.out.println(e.nextElement());
  31. }    

  33. }
  34.  
  35. }
     



Output:

  1. Real time examples
  2. Java Quiz
  3. Concept and interview Questions
  4. Concept and example program
  5. Java Interview Programs
  6. Java Interview Questions

Method overloading interview questions java

Posted by: Instanceofjava Posted date: March 16, 2016 / comment : 0

1.What is Method in java?

  • Method is a sub block of a class that contains logic of that class.
  • logic must be placed inside a method, not directly at class level, if we place logic at class level compiler throws an error.
  • So class level we are allowed to place variables and methods.
  • The logical statements such as method calls, calculations and printing related statements must be placed inside method, because these statements are considered as logic. 
  • For more information @ Methods in java



  1. package com.instanceofjava;
  2. class sample{
  3.  
  4. int a;
  5. int b;
  6.  
  7. System.out.println("instance of java"); // compiler throws an error.
  8.  
  9. }
  10.  

  1. package com.instanceofjava;
  2. class sample{
  3.  
  4. static int a=10;
  6.    
  7. public static void main(String args[]){

  9. System.out.println(a); // works fine,prints a value:10
  10.  
  11.  }
  12. }

2.What is meant by method overloading in java?


  • Defining multiple methods with same name is known as polymorphism.
  • Defining multiple methods with same name and with different arguments known as method overloading.

  1. package com.instanceofjava;
  2. class A{
  3.  
  4. public void show(int a){
  5. System.out.println("saidesh");
  6. }
  7.  
  8. public void show(int a,int b){
  9. System.out.println("ajay");
  10. }
  11.  
  12. public void show(float a){
  13. System.out.println("vinod");
  14. }
  15. public static void main(String args[]){
  16.  
  17. A a=new A();
  18.  
  19. a.show(10);
  20. a.show(1,2);
  21. a.show(1.2);
  22.  
  23. }
  24. }
Output:

  1. saidesh
  2. ajay
  3. vinod


3.What are the other names for method overloading?


  • Method overloading also known as static polymorphism or compile time polymorphism because at compile time itself we can tell which method going to get executed based on method arguments.
  • So method overloading also called as static binding. 

4.What are the basic rules of method overloading?

  • Defining a method with same name and differ in number of arguments
  • Defining a method with same name and differ in type of arguments
  • Defining a method with same name and differ in order of type of arguments
  • Return type of the method not involved in method overloading.

5.Can we overload static methods in java?

  • Yes. We can overload static methods in java.
  • Method overriding is not possible but method overloading is possible for static methods.
  • Before that lets see about method overloading in java.
  • lets see an example java program which explains static method overloading.
  1. class StaticMethodOverloading{
  2.  
  3. public static void staticMethod(){
  4.  
  5. System.out.println("staticMethod(): Zero arguments");
  6.  
  7. } 
  8.  
  9. public static void staticMethod(int a){
  10.  
  11. System.out.println("staticMethod(int a): one argument");
  12.  
  13. } 
  14.  
  15. public static void staticMethod(String str, int x){
  16.  
  17. System.out.println("staticMethod(String str, int x): two arguments");
  18.  
  19. }
  20.  
  21. public static void main(String []args){
  22.   
  23.   StaticMethodOverloading.staticMethod();
  24.   StaticMethodOverloading.staticMethod(12);
  25.   StaticMethodOverloading.staticMethod("Static method overloading",10);
  26.  
  27. }
  28. }


 Output:

  1. staticMethod(): Zero arguments
  2. staticMethod(int a): one argument
  3. staticMethod(String str, int x): two arguments


6.Can we overload main method in java?

Yes we can overload main method in java

Java Program to overload main method in java

  1. class mainMethodOverloading{
  2.  
  3. public static void main(boolean x){
  4.  
  5. System.out.println("main(boolean x) called ");
  6.  
  7. } 
  8.  
  9. public static void main(int x){
  10.  
  11. System.out.println("main(int x) called");
  12.  
  13. } 
  14.  
  15. public static void main(int a, int b){
  16.  
  17. System.out.println("main(int a, int b) called");
  18.  
  19. }
  20.  
  21. public static void main(String []args){
  22.    
  23.  
  24. System.out.println("main(String []args) called ");
  25.  
  26.   mainMethodOverloading.main(true);
  27.   mainMethodOverloading.main(10);
  28.  mainMethodOverloading.main(37,46);
  29.  
  30.  
  31. }
  32. }




 Output:

  1. main(String []args) called
  2. main(boolean x) called
  3. main(int x) called
  4. main(int a, int b) called

method overloading interview questions





7.Can we overload constructors in java?

  • Yes we can overload constructor in java

  1. package instanceofjava;
  2. class ConstructorChaining{
  3. int a,b 
  4. ConstructorChaining(){
  5. this(1,2);
  6.  System.out.println("Default constructor");
  7.  
  8. } 
  9.  
  10. ConstructorChaining(int x , int y){
  11.  
  12. this(1,2,3); 
  13. a=x;
  14. b=y;
  15.  System.out.println("Two argument constructor");
  16.  
  17. }
  18.  
  19. ConstructorChaining(int a , int b,int c){
  20.  System.out.println("Three argument constructor")
  21. } 
  22.  
  23. public static void main(String[] args){
  24.  
  25.  ConstructorChaining obj=new ConstructorChaining();
  26.   System.out.println(obj.a);
  27.   System.out.println(obj.b);
  28.  
  29. }
  30. }


You Might Like:



Subscribe to: Posts ( Atom )
Select Menu
Copyright © 2015-2025 instanceofjava.com , All rights reserved | Privacy policy | About Us