double

Double Types in Java

Overview

In Java, the double type is used to store decimal numbers with double precision. It is particularly useful for mathematical calculations, scientific data, and when dealing with numbers that require more precision than the float type.

Double Type in Java:

1. double: 64-bit double-precision floating-point number.

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Double Comparison Table

Type	Size (bits)	Range	Default Value
double	64	~±4.9E-324 to ±1.8E308	0.0

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Operations on Double Types

Arithmetic Operations

Operation	Symbol	Example
Addition	+	doubleValue + doubleValue
Subtraction	-	doubleValue - doubleValue
Multiplication	*	doubleValue * doubleValue
Division	/	doubleValue / doubleValue
Modulo	%	doubleValue % doubleValue

Relational Operations

Operation	Symbol	Example
Equal to	==	doubleValue == doubleValue
Not equal to	!=	doubleValue != doubleValue
Greater than	>	doubleValue > doubleValue
Less than	<	doubleValue < doubleValue
Greater than or equal to	>=	doubleValue >= doubleValue
Less than or equal to	<=	doubleValue <= doubleValue

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Type Casting

Implicit Casting (Widening)

• Automatically converts smaller types (e.g., float) to larger types (e.g., double).
  • Example:

    float floatValue = 10.5f;
    double doubleValue = floatValue;  // No explicit cast needed

Explicit Casting (Narrowing)

• Converts larger types (e.g., double) to smaller types (e.g., float) explicitly.
  • Example:

    double doubleValue = 100.99;
    float floatValue = (float) doubleValue;  // May lead to precision loss

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Precision and Rounding Issues

Floating-point types may introduce rounding errors due to the way numbers are stored in memory. It’s important to consider precision when using these types.

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Example Code

public class DoubleExamples {
    public static void main(String[] args) {
        // Initialize variable
        double doubleValue = 10.5;

        // Arithmetic Operations
        double sum = doubleValue + doubleValue;
        System.out.println("Sum: " + sum);

        // Relational Operations
        boolean isEqual = (doubleValue == doubleValue);
        System.out.println("Is Equal: " + isEqual);

        // Type Casting
        // Implicit casting (float to double)
        float floatValue = 10.5f;
        double implicitCast = floatValue;
        System.out.println("Implicit cast from float to double: " + implicitCast);

        // Explicit casting (double to float)
        double anotherDoubleValue = 100.99;
        float explicitCast = (float) anotherDoubleValue;
        System.out.println("Explicit cast from double to float: " + explicitCast);

        // Precision Issue Example
        double result = 0.1 + 0.2;
        System.out.println("0.1 + 0.2 == 0.3? " + (result == 0.3));  // Output: false
    }
}

For more: DoubleDataType.java