» » Integer Wrapper class

  • Integer  class is present in java.lang package.
  • java.lang.Integer  is used to represent integer primitive value in form of object.

Class Definition

  1. public final class Integer
  2. extends Number 
  3. implements Comparable<Integer>

Integer Class Constructors

1.public Integer(int value):
  • It takes int primitive value as an argument.
Java code to convert int primitive to Integer object


  1. package com.instanceofjavatutorial;
  2.  
  3. public class IntegerDemo {
  4.  
  5. public static void main(String[] args) {
  6.  


  7.  Integer obj=new Integer (37);
  8.  
  9.  System.out.println(obj);
  10.  
  11.  
  12. }
  13. }

Output:
  1. 37

2.public Integer(String s)  throws NumberFormatException:

  • It takes String value as an argument. 

Java code to convert String to Integer object


  1. package com.instanceofjavatutorial;
  2.  
  3. public class IntegerDemo {
  4.  
  5. public static void main(String[] args) {
  6.  


  7.  Integer obj=new Integer ("123");
  8.  
  9.  System.out.println(obj);
  10.  
  11.  
  12. }
  13. }

Output:
  1. 123

Integer Class Methods:

3.public static int parseInt(String s) throws NumberFormatException :
  • This method takes String as an argument and converts to the int value
  • Static method present in Integer Class used to parse the string to the corresponding int value.in
  • We can use this method by class name Integer.parseInt("number").
  • If the String contains non numeric value then this method throws NumberFormatException 

 Java Program to parse a string or convert String to Integer value

  1. package com.instanceofjavatutorial;
  2.  
  3. public class IntegerParseIntDemo {
  4.  
  5. public static void main(String[] args) {
  6.  

  7.  int x= Integer.parseInt("34");
  8.   System.out.println(x);
  9.  
  10.  int y=  Integer.parseInt("56");
  11.    System.out.println(y);
  12.  
  13.  int z=  Integer.parseInt("98");
  14.  System.out.println(z);
  15.  
  16. }
  17. }

Output:
  1. 34
  2. 56
  3. 98
4.public int intValue()

  • This method returns the int value from the Integer Object.
  • obj.intValue()- returns a int value of Object obj.



Java Program to get int value from a Integer Object.

  1. package com.instanceofjavatutorial;
  2.  
  3. public class IntegerIntValueDemo {
  4.  
  5. public static void main(String[] args) {
  6.  

  7.  Integer obj= new Integer(25);

  8.  
  9.  int y= obj.intValue();
  10.  
  11.  System.out.println(y);
  12.  
  13. }
  14. }

Output:
  1. 25

3.public int compareTo(Integer anotherInteger) 

  •  This method is used to compare two Integer Objects and returns int value
  •  0- Integer is equal to the argument Integer
  • < 0 if this Integer is numerically less than the argument Integer
  • > 0 if this Integer is numerically greater than the argument

Java Program to compare two Integer Objects.

  1. package com.instanceofjavatutorial;
  2.  
  3. public class IntegercompareToDemo {
  4.  
  5. public static void main(String[] args) {
  6.  

  7.    Integer obj1 = new Integer("34");
  8.    Integer obj2 = new Integer("08");
  9.  
  10.   int val =  obj1.compareTo(obj2);
  11.  
  12.    if(val > 0) {
  13.  
  14.    System.out.println("obj1 is greater than obj2");
  15.  
  16.    }
  17.    else if(val < 0) {
  18.  
  19.    System.out.println("obj1 is less than obj2");
  20.  
  21.    }
  22.    else {
  23.  
  24.    System.out.println("obj1 is equal to obj2");
  25.  
  26.    }
  27. }
  28. }

Output:
  1. obj1 is greater than obj2


4.public float floatValue()

  • This method used to convert integer value to float value.

Java Program to convert Integer to float

  1. package com.instanceofjavatutorial;
  2.  
  3. public class IntegerfloatValueDemo {
  4.  
  5. public static void main(String[] args) {
  6.  

  7.    Integer obj1 = new Integer("34");
  8.    Integer obj2 = new Integer("23");
  9.    
  10.     float f 1= obj1.floatValue();
  11.     float f 2= obj2.floatValue();
  12.  
  13.    System.out.println(f1);
  14.    System.out.println(f2); 

  15. }
  16. }

Output:
  1. 34.0
  2. 23.0

5.public String toString()

  • This method used to convert Integer to string object.

Java Program to convert Integer to String Object.

  1. package com.instanceofjavatutorial;
  2.  
  3. public class IntegerfloatValueDemo {
  4.  
  5. public static void main(String[] args) {
  6.  

  7.    Integer obj1 = new Integer("12");
  8.    Integer obj2 = new Integer("34");
  9.    
  10.     String  str1= obj1.toString();
  11.     String  f 2= obj2.toString();
  12.  
  13.    System.out.println(str1);
  14.    System.out.println(str2); 

  15. }
  16. }

Output:
  1. 12
  2. 34

Instance Of Java

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