Widening casting is done automatically when passing a smaller size type to a larger size type:

for ex:

public class Main {

  public static void main(String[] args) {

    int myInt = 9;

    double myDouble = myInt; // Automatic casting: int to double

​

    System.out.println(myInt);      // Outputs 9

    System.out.println(myDouble);   // Outputs 9.0

  }

}

Narrowing casting must be done manually by placing the type in parentheses in front of the value:

for ex:

public class Main {

  public static void main(String[] args) {

    double myDouble = 9.78d;

    int myInt = (int) myDouble; // Manual casting: double to int

​

    System.out.println(myDouble);   // Outputs 9.78

    System.out.println(myInt);      // Outputs 9

  }

}