Java Type Casting

Type casting in Java is a process of assigning a value of one primitive data type to another. It is an essential concept in Java programming, enabling flexibility and precision in handling different data types. There are two main types of casting in Java: Widening Casting (automatic) and Narrowing Casting (manual).

Widening Casting

Widening casting happens automatically when converting a smaller data type to a larger one. This process is seamless and does not require explicit conversion by the programmer. The order of data types from smaller to larger is as follows:

byte -> short -> char -> int -> long -> float -> double

byte -> short -> char -> int -> long -> float -> double

Example of Widening Casting

In this example, the integer smallNum is automatically cast to a double largeNum without any explicit conversion.

public class Main {
    public static void main(String[] args) {
        int smallNum = 9;
        double largeNum = smallNum; // Automatic casting: int to double
        System.out.println(smallNum); // Outputs 9
        System.out.println(largeNum); // Outputs 9.0
    }
}

public class Main {

    public static void main(String[] args) {

        int smallNum = 9;

        double largeNum = smallNum; // Automatic casting: int to double

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

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

    }

}

Narrowing Casting

Narrowing casting must be performed manually, as it involves converting a larger data type to a smaller one. This process requires the programmer to use explicit conversion by placing the target type in parentheses before the value.

double -> float -> long -> int -> char -> short -> byte

double -> float -> long -> int -> char -> short -> byte

Example of Narrowing Casting

In this example, the double bigNum is manually cast to an integer smallNum using explicit conversion.

public class Main {
    public static void main(String[] args) {
        double bigNum = 9.78;
        int smallNum = (int) bigNum; // Manual casting: double to int
        System.out.println(bigNum); // Outputs 9.78
        System.out.println(smallNum); // Outputs 9
    }
}

public class Main {

    public static void main(String[] args) {

        double bigNum = 9.78;

        int smallNum = (int) bigNum; // Manual casting: double to int

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

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

    }

}

Real-Life Application of Type Casting

Type casting can be useful in various real-world scenarios. Consider a program that calculates the percentage of a user’s score in relation to the maximum score in a game. Type casting ensures the result is a floating-point number rather than an integer.

Example

In this example, the integer userPoints is cast to a float before performing the division, ensuring an accurate floating-point result.

public class GameScore {
    public static void main(String[] args) {
        int maxPoints = 500; // Maximum possible score in the game
        int userPoints = 423; // User's actual score

        // Calculate the user's percentage score
        float percentageScore = (float) userPoints / maxPoints * 100;
        System.out.println("User's percentage score is " + percentageScore);
    }
}

public class GameScore {

    public static void main(String[] args) {

        int maxPoints = 500; // Maximum possible score in the game

        int userPoints = 423; // User's actual score

​

        // Calculate the user's percentage score

        float percentageScore = (float) userPoints / maxPoints * 100;

        System.out.println("User's percentage score is " + percentageScore);

    }

}