Convert String to Byte Array in Java Using getBytes(Charset) Method

Last Updated : 22 Nov, 2024

To convert a string to a byte array, we use the getBytes(Charset) method In Java that transforms the string into a sequence of bytes based on a specified character encoding. This method returns the byte array and relies on the Charset class to handle character-to-byte mappings.

Example:

Java

// Java program to convert a String to a byte array 
// using getBytes(Charset) method with UTF-8 encoding
import java.nio.charset.StandardCharsets;

public class StringToByteArray {
  
    public static void main(String[] args) {
        
        // sample string
        String s = "hello";

        // Convert string to byte array using UTF-8 encoding
        byte[] b = s.getBytes(StandardCharsets.UTF_8);

        // Print the byte array
        for (byte b1 : b) {
            System.out.print(b1 + " ");
        }
    }
}

Output

104 101 108 108 111

Explanation: The above program converts the string “hello” into a byte array using UTF-8 encoding by using the getBytes(StandardCharsets.UTF_8) method. Then it prints each byte of the resulting byte array.

Syntax of getBytes(Charset) Method

byte[] byteArray = string.getBytes(Charset charset);

Parameter: charset is the character set used to encode the string. For example, StandardCharsets.UTF_8 or Charset.forName("UTF-8").

Return type: This function returns the resulting byte array.

Important Points:

This method always replaces malformed input and unmappable character sequence with its charset’s default replacement byte array.
If the given charset is not a valid charset, then this method will throw UnsupportedEncodingException.
The length of the byte array is not the same as the given string, it depends upon the character encoding.

Other Ways to Convert a String to Byte Array Using getBytes(Charset)

1. Convert String to Byte Array Using UTF-16 Charset

Example:

Java

// Java Program to illustrate how to
// convert a string to byte array
// Using getBytes(Charset charset)
import java.io.*;

class GFG {
    public static void main (String[] args) {
        String s = "Hello GeeksforGeeks";

        // Display the string before conversion
        System.out.println("String: " + s);

        try {
            // Converting string to byte array
            // Using getBytes(Charset charset) method
            // Here, we convert the string into UTF-16 values
            byte[] r = s.getBytes("UTF-16");

            // Displaying the converted string after 
            // conversion into UTF-16
            System.out.println("Result: ");
            for (int i = 0; i < r.length; i++) {
                System.out.print(r[i] + " ");
            }
        } catch (Exception e) {
            System.out.println("Error: " + e);
        }
    }
}

Output

String: Hello GeeksforGeeks
Result: 
-2 -1 0 72 0 101 0 108 0 108 0 111 0 32 0 71 0 101 0 101 0 107 0 115 0 102 0 111 0 114 0 71 0 101 0 101 0 107 0 115

Explanation: The above example converts the string "Hello GeeksforGeeks" into a byte array using the UTF-16 charset with the getBytes("UTF-16") method. Then it prints each byte of the resulting byte array to the console.

2. Convert String to Byte Array Using US-ASCII Charset

Example:

Java

// Java Program to illustrate how to
// convert a string to byte array
// Using getBytes(Charset charset)
import java.io.*;
import java.util.Arrays;

class GFG{
    
public static void main (String[] args) 
{
    
    String s1 = "Hello GFG";
    
    // Display the string before conversion
    System.out.println("String: " + s1);
    
    try
    { 
        // Converting string to byte array
        // Using getBytes(Charset charset) method
        // Here, we converts into US-ASCII values
        byte[] r = s1.getBytes("US-ASCII"); 

        // Displaying converted string after conversion 
        // into US-ASCII 
        System.out.println("Byte Array: " + Arrays.toString(r));
    } 
  
    catch (UnsupportedEncodingException g) 
    {
        System.out.println("Unsupported character set" + g); 
    } 
}
}

Output

String: Hello GFG
Byte Array: [72, 101, 108, 108, 111, 32, 71, 70, 71]

Explanation: The above example converts the string "Hello GFG" into a byte array using the US-ASCII charset with the getBytes("US-ASCII") method. Then it prints the resulting byte array using Arrays.toString() to display the ASCII values of the characters.

Java Program to Convert Byte Array to Hex String

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Practice Tags :

Convert String to Byte Array in Java Using getBytes(Charset) Method

Syntax of getBytes(Charset) Method

Other Ways to Convert a String to Byte Array Using getBytes(Charset)

1. Convert String to Byte Array Using UTF-16 Charset

2. Convert String to Byte Array Using US-ASCII Charset

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