What are the differences between an Integer and an int in Java?

Integer (Wrapper class) and int (primitive data type)

• The major difference between an Integer and an int is that Integer is a wrapper class whereas int is a primitive data type.
• An int is a data type that stores 32-bit signed two’s complement integer whereas an Integer is a class that wraps a primitive type int in an object.
• An Integer can be used as an argument to a method that requires an object, whereas int can be used as an argument to a method that requires an integer value, that can be used for arithmetic expression.
• An int datatype helps to store integer values in memory whereas Integer helps to convert int into an object and to convert an object into an int.
• The variable of int type is mutable unless it is marked as final and the Integer class contains one int value and is immutable.

Example1

Live Demo

public class PrimitiveDataTypeTest {
   public static void main(String []args) {
      // Declaration of int
      int a = 20;
      int b = 40;
      int result = a+b;
      System.out.println("Result is: " + result);
   }
}

Output

Result is: 60

Example2

Live Demo

public class WrapperClassTest {
   public static void main(String []args) {
      int a = 20;
      Integer b = Integer.valueOf(a);
      System.out.println("Converted Value of b is: " + b);
      Integer c = new Integer(30);
      int d = c.intValue();
      System.out.println("Converted Value of d is: " + d);
   }
}

Output

Converted Value of b is: 20
Converted Value of d is: 30