Casting Incompatible Types

A narrowing conversion is to explicitly make the value narrower. A cast is an explicit type conversion. It has this general form:


(target-type) value

target-type specifies the desired type. The following code casts int type value to byte type value.


public class Main {
  public static void main(String[] argv) {
    int a = 1234;
    byte b;

    b = (byte) a;

    System.out.println("a is " + a);
    System.out.println("b is " + b);
  }
}

The output:


a is 1234
b is -46

Truncation happens when assigning a floating-point value to an integer value. For example, if the value 1.23 is assigned to an integer, the resulting value will simply be 1.


public class Main {

  public static void main(String args[]) {
    byte b;
    int i = 1;
    double d = 1.123;

    System.out.println("Conversion of double to int.");
    i = (int) d;
    System.out.println("d: " + d + " i: " + i);

    System.out.println("Conversion of double to byte.");
    b = (byte) d;
    System.out.println("d: " + d + " b: " + b);

  }
}

This program generates the following output:


Conversion of double to int.
d: 1.123 i: 1
Conversion of double to byte.
d: 1.123 b: 1

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