In this tutorial, you will learn how to convert a float value to a double in Java, with examples to demonstrate implicit and explicit conversion methods.

Java – Convert float to double

Converting float to double in Java – In Java, a float value can be converted to a double in two ways: implicitly and explicitly. Since double has a larger range than float, this conversion is straightforward and can be handled by Java automatically.

Implicit Conversion from float to double

Java automatically performs an implicit (widening) conversion from float to double. This happens because double has a larger memory size and range than float, so there’s no risk of data loss.

Example of Implicit Conversion

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public class FloatToDoubleExample {

    public static void main(String[] args) {
        float floatVal = 3.14f;
        double doubleVal = floatVal; // Implicit conversion from float to double
        System.out.println("Float value: " + floatVal);
        System.out.println("Double value after conversion: " + doubleVal);
    }
}

Output

Float value: 3.14
Double value after conversion: 3.140000104904175

In this example, the float value 3.14 is automatically converted to a double without any explicit cast.

Explicit Conversion from float to double

Although implicit conversion is straightforward, you can also explicitly cast a float to double to make your code more readable.

Example of Explicit Conversion

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public class FloatToDoubleExample {

    public static void main(String[] args) {
        float floatVal = 3.14f;
        double doubleVal = (double) floatVal; // Explicit conversion
        System.out.println("Float value: " + floatVal);
        System.out.println("Double value after explicit conversion: " + doubleVal);
    }
}

Output

Float value: 3.14
Double value after explicit conversion: 3.140000104904175

In this example, the float value is explicitly cast to a double, even though this is unnecessary for widening conversions. This can sometimes enhance code readability.

Conclusion

Converting a float to a double in Java is simple due to implicit widening. Java handles this conversion automatically, but explicit casting is also an option if you prefer clarity in your code.