Type casting in Java

 

✅ What is Type Casting?

Type Casting in Java is the process of converting a value from one data type to another.

Java has two types of type casting:

1. Widening (Implicit) Casting – small → large type

2. Narrowing (Explicit) Casting – large → small type

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🔹 1. Widening Type Casting (Automatic)

Definition: Converting a smaller data type to a larger one.
👉 Safe conversion – done automatically by Java.

🔸 Example:

public class WideningExample {
    public static void main(String[] args) {
        int a = 10;
        double b = a;  // int → double

        System.out.println("int value: " + a);
        System.out.println("double value: " + b);
    }
}

Output:

int value: 10  
double value: 10.0

✅ Widening Order:

byte → short → int → long → float → double

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🔹 2. Narrowing Type Casting (Manual)

Definition: Converting a larger data type to a smaller one.
👉 Not safe automatically, so explicit casting is required.

🔸 Example:

public class NarrowingExample {
    public static void main(String[] args) {
        double a = 9.78;
        int b = (int) a;  // double → int

        System.out.println("double value: " + a);
        System.out.println("int value: " + b);
    }
}

Output:

double value: 9.78  
int value: 9

⚠️ Decimal part is lost during narrowing.

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🔸 Example with Character

public class CharCasting {
    public static void main(String[] args) {
        char c = 'A';
        int ascii = c;  // char → int (widening)
        System.out.println("ASCII of A is: " + ascii);

        int n = 66;
        char ch = (char) n;  // int → char (narrowing)
        System.out.println("Character of 66 is: " + ch);
    }
}

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🔹 Summary Table

Type	Conversion Example	Casting Needed?
Widening	int → double	❌ No
Narrowing	double → int	✅ Yes
Char to Int	'A' → 65	❌ No
Int to Char	65 → 'A'	✅ Yes