Java Double.byteValue() Method
Last Updated :
15 May, 2025
The Double.byteValue() is a built-in method in Java Double class. This method converts the value of a Double object to a byte type. Basically, it is used for narrowing the primitive conversion of the Double type to a byte value.
In this article, we are going to learn about the Double.byteValue() method in Java with syntax and examples.
Syntax of byteValue() Method
public byte byteValue()
- Parameters: The function does not accept any parameters.
- Return Value: This method returns the double value represented by this object converted to type byte.
Examples of Java Double.byteValue() Method
Example 1: In this example, we are going to convert large positive numbers.
Java
// Java program showing byteValue() with a large number
import java.lang.Double;
public class Geeks {
public static void main(String[] args) {
Double value = 1023d;
byte b = value.byteValue();
System.out.println("Byte value of 1023d: " + b);
value = 12d;
b = value.byteValue();
System.out.println("Byte value of 12d: " + b);
}
}
OutputByte value of 1023d: -1
Byte value of 12d: 12
Explanation: Here, the value 1023 exceeds the byte range, so the output wraps around to -1.
Example 2: In this example, we are going to see what happens with negative values.
Java
// Java program showing byteValue() with negative values
import java.lang.Double;
public class Geeks {
public static void main(String[] args) {
Double value = -1023d;
byte b = value.byteValue();
System.out.println("Byte value of -1023d: " + b);
value = -12d;
b = value.byteValue();
System.out.println("Byte value of -12d: " + b);
}
}
OutputByte value of -1023d: 1
Byte value of -12d: -12
Explanation: Here, when -1023 is converted, it also wraps around due to overflow and produces an unexpected result i.e. 1.
Example 3: In this example, we are going to see what happens with decimal values.
Java
// Java program showing byteValue() with decimal values
import java.lang.Double;
public class Geeks {
public static void main(String[] args) {
Double value = 11.24;
byte b = value.byteValue();
System.out.println("Byte value of 11.24: " + b);
value = 6.0;
b = value.byteValue();
System.out.println("Byte value of 6.0: " + b);
}
}
OutputByte value of 11.24: 11
Byte value of 6.0: 6
Explanation: Here, the decimal part is truncated, not rounded and 11.24 becomes 11.
Example 4: In this example, we are going to see what happens when we do invalid conversion from string.
Java
// Invalid conversion from string
import java.lang.Double;
public class Geeks {
public static void main(String[] args) {
// cannot assign String to Double
Double value = "45";
byte b = value.byteValue();
System.out.println("Byte value: " + b);
}
}
Output:
error: incompatible types: String cannot be converted to Double
Explanation: We cannot assign a string directly to a Double variable.