Java Type Casting
Java Type Casting
Type casting is when you assign a value of one primitive data type to another type.
In Java, there are two types of casting:
- Widening Casting (automatically) - converting a smaller type
to a larger type size
byte->short->char->int->long->float->double
- Narrowing Casting (manually) - converting a larger type
to a smaller size type
double->float->long->int->char->short->byte
Widening Casting
Widening casting is done automatically when passing a smaller size type to a larger size type:
Example
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
Narrowing casting must be done manually by placing the type in parentheses ()
in front of the value:
Example
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
}
}
Real-Life Example
Here's a real-life example of type casting where we create a program to calculate the percentage of a user's score in relation to the maximum score in a game.
We use type casting to make sure that the result is a floating-point value, rather than an integer:
Example
// Set the maximum possible score in the game to 500
int maxScore = 500;
// The actual score of the user
int userScore = 423;
/* Calculate the percantage of the user's score in relation to the maximum available score.
Convert userScore to float to make sure that the division is accurate */
float percentage = (float) userScore / maxScore * 100.0f;
System.out.println("User's percentage is " + percentage);
