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Java Program to Convert Byte Array to String

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  • Difficulty Level : Easy
  • Last Updated : 03 May, 2022
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A byte is 8 bits of binary data so do byte array is an array of bytes used to store the collection of binary data. There are multiple ways to change byte array to String in Java, you can either use methods from JDK, or you can use open-source complementary APIs like Apache commons and Google Guava. These APIs provide at least two sets of methods to create a String from a byte array; one, which uses default platform encoding, and the other which takes character encoding.

Different Methods to Convert Byte Array to String

  1. Using UTF-8 encoding
  2. Using String Class Constructor  

Method 1: Using UTF-8 encoding

It’s also one of the best practices for specifying character encoding while converting bytes to the character in any programming language. It might be possible that your byte array contains non-printable ASCII characters. Let’s first see JDK’s way of converting byte[] to a string. Some programmers, also recommend using Charset over String for specifying character encoding, e.g. instead of “UTF-8” use StandardCharsets.UTF_8 mainly to avoid Unsupported Encoding Exception in the worst case.

Case 1: Without character encoding

We can convert the byte array to String for the ASCII character set without even specifying the character encoding. The idea is to pass the byte[] to the string. It is as shown in the below example which is as follows:

Example:

Java




// Java Program to Convert Byte Array to String
// Without character encoding
  
// Importing required classes
import java.io.IOException;
import java.util.Arrays;
  
// Main class
class GFG {
    // Main driver method
    public static void main(String[] args)
        throws IOException
    {
        // Getting bytes from the custom input string
        // using getBytes() method and
        // storing it in a byte array
        byte[] bytes = "Geeksforgeeks".getBytes();
  
        System.out.println(Arrays.toString(bytes));
  
        // Creating a string from the byte array
        // without specifying character encoding
        String string = new String(bytes);
  
        // Printing the string
        System.out.println(string);
    }
}

Output

[71, 101, 101, 107, 115, 102, 111, 114, 103, 101, 101, 107, 115]
Geeksforgeeks

Case 2: With character encoding

We know that a byte holds 8 bits, which can have up to 256 distinct values. This works fine for the ASCII character set, where only the first 7 bits are used. For character sets with more than 256 values, we should explicitly specify the encoding, which tells how to encode characters into sequences of bytes. 

Note: Here we are using StandardCharsets.UTF_8 to specify the encoding. Before Java 7, we can use the Charset. for Name(“UTF-8”).

Example 2:

Java




// Java Program to Convert Byte Array to String
// With character encoding
  
// Importing required classes
import java.io.IOException;
import java.nio.charset.StandardCharsets;
  
// Main class
class GFG {
  
    // Main driver method
    public static void main(String[] args)
        throws IOException
    {
  
        // Custom input string is converted into array of
        // bytes and stored
        byte[] bytes = "Geeksforgeeks".getBytes(
            StandardCharsets.UTF_8);
  
        // Creating a string from the byte array with
        // "UTF-8" encoding
        String string
            = new String(bytes, StandardCharsets.UTF_8);
  
        // Print and display the string
        System.out.println(string);
    }
}

Output

Geeksforgeeks

Method 2: Using String Class Constructor  

Java




// Java Program to Illustrate Conversion of
// Byte Array to String
// Using String Class Constructor
  
// Class
class GFG {
  
    // Main driver method
    public static void main(String[] args)
    {
  
        // Try block to check for exceptions
        try {
  
            // Getting bytes of input byte array
            // using getBytes() method
            byte[] input = "GeeksforGeeks".getBytes();
  
            // Creating a corresponding string
            String str = new String(input);
  
            // Printing the above string
            System.out.println(str);
        }
  
        // Catch block to handle exceptions
        catch (Exception e) {
  
            // Display exceptions along with line number
            // using printStackTrace() method
            e.printStackTrace();
        }
    }
}

Output

GeeksforGeeks

Conclusion: We should focus on the type of input data when working with conversion between byte[] array and String in Java.

  • Use String class when you input data is string or text content.
  • Use Base64 class when you input data in a byte array.

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