How to convert String to byte[] in Java?

In Java, we can use str.getBytes(StandardCharsets.UTF_8) to convert a String into a byte[].

  String str = "This is a String";

  //  default charset, a bit dangerous
  byte[] output1 = str.getBytes();

  // in old days, before java 1.7
  byte[] output2 = str.getBytes(Charset.forName("UTF-8"));

  // the best , java 1.7+ , new class StandardCharsets
  byte[] output3 = str.getBytes(StandardCharsets.UTF_8);

1. Convert String to byte[]

Below is a complete example of converting a String to a byte[] type, and Base64 encodes it.

ConvertStringToBytes.java

package com.favtuts.string;

import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.Base64;

public class ConvertStringToBytes {
    
    public static void main(String[] args) {
        String example = "This is an example";

        //  default charset, a bit dangerous
        byte[] output1 = example.getBytes();

        // in old days, before java 1.7
        byte[] output2 = example.getBytes(Charset.forName("UTF-8"));

        // the best , java 1.7+
        byte[] output3 = example.getBytes(StandardCharsets.UTF_8);

        System.out.println("Text : " + example);

        // base64 encode
        String base64encoded = Base64.getEncoder().encodeToString(output3);

        System.out.println("Text [Base64] : " + base64encoded);
    }
}

Output

Text : This is an example
Text [Base64] : VGhpcyBpcyBhbiBleGFtcGxl

2. Convert byte[] to String

In Java, we can use new String(bytes, StandardCharsets.UTF_8) to convert byte[] to a String.

ConvertBytesToString.java

package com.favtuts.string;

import java.nio.charset.StandardCharsets;

public class ConvertBytesToString {
    
    public static void main(String[] args) {
        // String to byte[]
        byte[] bytes = "tuts.heomi.net".getBytes(StandardCharsets.UTF_8);

        // byte[] to String
        String s = new String(bytes, StandardCharsets.UTF_8);
        
        // tuts.heomi.net
        System.out.println(s);
    }
}

Output

tuts.heomi.net

Download Source Code

$ git clone https://github.com/favtuts/java-core-tutorials-examples

$ cd java-string

4. References

• How to create Zip file in Java
• How to convert byte arrays to String in Java
• Java 11 – String JavaDoc
• Wikipedia – UTF-8