Type Conversion of data Type

Assigning a value of one type to a variable of another type is known as Type Casting. If the data types are compatible, then Java will perform the conversion automatically known as Automatic Type Conversion and if not then they need to be casted or converted explicitly.
Example :

int x = 10;
byte y = (byte)x;

In Java, type casting is classified into two types,

• Widening Casting(Implicit)

• Narrowing Casting(Explicitly done)
 

Widening or Automatic type converion

Automatic Type casting take place when,

• the two types are compatible
• the target type is larger than the source type

Example :

public class Test
{
    public static void main(String[] args)
    {
      int i = 100;
      long l = i; //no explicit type casting required
      float f = l; //no explicit type casting required
      System.out.println("Int value "+i);
      System.out.println("Long value "+l);
      System.out.println("Float value "+f);
    }

}

O/P :- 

Int value 100 

Long value 100 

Float value 100.0 

Narrowing or Explicit type conversion

When you are assigning a larger type value to a variable of smaller type, then you need to perform explicit type casting.
Example :

public class Test
{
    public static void main(String[] args)
    {
      double d = 100.04;
      long l = (long)d;  //explicit type casting required
      int i = (int)l; //explicit type casting required

      System.out.println("Double value "+d);
      System.out.println("Long value "+l);
      System.out.println("Int value "+i);
    }

}

O/P : 

Double value 100.04 

Long value 100 

Int value 100