Java Example Program to convert binary to decimal

Posted by: Instanceofjava Posted date: March 21, 2016 / comment : 2


  • Famous interview java question on conversions . 
  • We can convert binary to decimal in two ways
    1.Using Integer.parseInt() method
    2.Using custom logic



1.Write a Java Program to convert binary to decimal number in java without using Integer.parseInt() method.

  1. import java.util.Scanner;
  2. public class DecimalFromBinary {
  3.  
  4.     /**
  5.      *www.instanceofjava.com
  6.      */
  7.  
  8.  public static void main(String[] args) {
  9.         
  10.  Scanner in = new Scanner( System.in );
  11.  System.out.println("Enter a binary number: ");
  12.  
  13.   int  binarynum =in.nextInt();
  14.   int binary=binarynum;
  15.         
  16. int decimal = 0;
  17. int power = 0;
  18.  
  19. while(true){
  20.  
  21.  if(binary == 0){
  22.  
  23.         break;
  24.  
  25.  } else {
  26.  
  27.    int tmp = binary%10;
  28.    decimal += tmp*Math.pow(2, power);
  29.    binary = binary/10;
  30.    power++;
  31.  
  32.  }
  33. }
  34.         System.out.println("Binary="+binary+" Decimal="+decimal); ;
  35. }
  36.  
  37. }

Output:


  1. Enter a binary number: 
  2. 101
  3. Binary=101 Decimal=5




2.Write a Java Program to convert binary to decimal number in java using Integer.parseInt() method.



  1. import java.util.Scanner;
  2. public class ConvertBinaryToDecimal{
  3.  
  4.     /**
  5.      *www.instanceofjava.com
  6.      */
  7.  
  8.  public static void main(String[] args) {
  9.         
  10.  Scanner in = new Scanner( System.in );
  11.  
  12.  System.out.println("Enter a binary number: ");
  13.  String binaryString =input.nextLine();
  14.  
  15.  System.out.println("Result: "+Integer.parseInt(binaryString,2));

  17.  
  18. }
  19.  
  20. }


Output:


  1. Enter a binary number:
  2. 001
  3. Result: 1

java program to convert binary to decimal


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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

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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
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