How to Convert a String value to Byte value in Java with Examples

Last Updated : 4 Sep, 2026

A String in Java may contain a numeric value as text, while byte is a primitive data type used to store small integer values. Java provides methods in the Byte wrapper class to convert a numeric String into a byte.

  • The byte data type stores values from -128 to 127.
  • The input String must contain a valid byte value; otherwise, the conversion throws a NumberFormatException.
  • Byte.parseByte() returns a primitive byte, while Byte.valueOf() returns a Byte object.

Examples:

Input: String = "25"
Output: 25

Input: String = "-100"
Output: -100

Methods to Convert String to Byte

1. Using Byte.parseByte() Method

The parseByte() method of the Byte class converts a numeric String into a primitive byte value.

Syntax

Byte.parseByte(str);

Java 
public class Main {

    // Convert String to byte
    public static byte convertStringToByte(String str) {
        return Byte.parseByte(str);
    }

    public static void main(String[] args) {

        String stringValue = "25";

        byte byteValue = convertStringToByte(stringValue);

        System.out.println(
            stringValue + " after converting into byte = "
            + byteValue
        );
    }
}

Output
25 after converting into byte = 25

Explanation: Byte.parseByte() reads the numeric value from the String and returns its equivalent primitive byte value. If the String does not contain a valid byte value, it throws NumberFormatException.

2. Using Byte.valueOf() Method

The valueOf() method of the Byte class converts a numeric String into a Byte object. The returned Byte object can also be automatically unboxed when assigned to a primitive byte.

Syntax

Byte.valueOf(str);

Java 
public class Main {

    // Convert String to byte
    public static byte convertStringToByte(String str) {
        return Byte.valueOf(str);
    }

    public static void main(String[] args) {

        String stringValue = "50";

        byte byteValue = convertStringToByte(stringValue);

        System.out.println(
            stringValue + " after converting into byte = "
            + byteValue
        );
    }
}

Output
50 after converting into byte = 50

Explanation: Byte.valueOf() converts the numeric String into a Byte object. In this program, Java automatically converts the returned Byte object into a primitive byte through unboxing.

Handling Invalid Input

If the String contains a value outside the byte range or a non-numeric value, Java throws NumberFormatException.

Java 
public class Main {

    public static void main(String[] args) {

        String str = "200";

        try {
            byte value = Byte.parseByte(str);
            System.out.println("Byte value: " + value);
        } catch (NumberFormatException e) {
            System.out.println("Invalid byte value: " + str);
        }
    }
}

Output
Invalid byte value: 200

Explanation: Here, 200 cannot be represented by a Java byte because the valid range is -128 to 127.

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