Double byteValue() Method in Java with Examples

The java.lang.Double.byteValue() is a built-in method in Java that returns the value of this Double as a byte(by casting to a byte). Basically it used for narrowing primitive conversion of Double type to a byte value.

Syntax:

public byte byteValue()

Parameters: The function does not accept any parameter.

Return Value: This method returns the double value represented by this object converted to type byte.

Examples:

Input : 12
Output : 12

Input : 1023
Output : -1

Below programs illustrates the use of java.lang.Double.byteValue() function:

Program 1:

// Program to illustrate the Double.byteValue() method
import java.lang.*;

public class GFG {

    public static void main(String[] args)
    {

        Double value = 1023d;

        // Returns the value of Double as a byte
        byte byteValue = value.byteValue();
        System.out.println("Byte Value of num = " + byteValue);

        // Another example
        value = 12d;
        byteValue = value.byteValue();
        System.out.println("Byte Value of num = " + byteValue);
    }
}

Output:

Byte Value of num = -1
Byte Value of num = 12

Program 2 : Demonstrates the byte value for a negative number.

// Java code to illustrate java.lang.Double.byteValue() method
import java.lang.*;

public class GFG {

    public static void main(String[] args)
    {

        Double value = -1023d;

        // Returns the value of Double as a byte
        byte byteValue = value.byteValue();
        System.out.println("Byte Value of num = " + byteValue);

        // Another example
        value = -12d;
        byteValue = value.byteValue();
        System.out.println("Byte Value of num = " + byteValue);
    }
}

Output:

Byte Value of num = 1
Byte Value of num = -12

Program 3 : When a decimal value is passed in argument.

// Program to illustrate java.lang.Double.byteValue() method

import java.lang.*;

public class GFG {

    public static void main(String[] args)
    {

        Double value = 11.24;

        // Returns the value of Double as a byte
        byte byteValue = value.byteValue();
        System.out.println("Byte Value of num = " + byteValue);

        // Another example
        value = 6.0;
        byteValue = value.byteValue();
        System.out.println("Byte Value of num = " + byteValue);
    }
}

Output:

Byte Value of num = 11
Byte Value of num = 6

Program 4 : When a string value is passed as argument.

// Code to illustrate Double.byteValue()
import java.lang.*;

public class GFG {

    public static void main(String[] args)
    {

        Double value = "45";

        // Returns the value of Double as a byte
        byte byteValue = value.byteValue();
        System.out.println("Byte Value of num = " + byteValue);
    }
}

Compile Errors:

prog.java:9: error: incompatible types: String cannot be converted to Double
        Double value = "45";
                       ^
1 error

Reference: https://docs.oracle.com/javase/8/docs/api/java/lang/Double.html#byteValue–