Encode a String into a byte array in Java

This post will discuss how to encode a string into a byte array in Java.

There are several ways to encode a string into a byte array in Java, which is the process of translating the sequence of characters in the string into a sequence of bytes using a specific character set. Here are some possible methods:

1. Using `getBytes()` method

We can encode the string into a sequence of bytes using the String.getBytes() method, which is an overloaded method that can encode a string using the platform’s default character set. This method returns a byte array that contains the encoded string. For example:

import java.util.Arrays;

public class Main

{

public static void main(String[] args)

{

String str = "Java";

// encode the string using the platform's default character set

byte[] bytes = str.getBytes();

System.out.println(Arrays.toString(bytes)); // [74, 97, 118, 97]

}

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If our string uses a different encoding than the default charset, specify that character encoding in the second argument to the String.getBytes() method. The second argument can accept a named character set or a provided character set.

import java.nio.charset.StandardCharsets;

import java.util.Arrays;

public class Main

{

public static void main(String[] args)

{

String str = "Java";

// encode a string using the UTF_16 character set

byte[] bytes = str.getBytes(StandardCharsets.UTF_16);

System.out.println(Arrays.toString(bytes)); // [-2, -1, 0, 74, 0, 97, 0, 118, 0, 97]

}

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To convert a byte array back to a string, we can pass the byte array to the String() constructor with the charset used for encoding. Here’s an example of this approach:

import java.nio.charset.StandardCharsets;

public class Main

{

public static void main(String[] args)

{

String str = "Java";

byte[] bytes = str.getBytes(StandardCharsets.UTF_8);

String decodedStr = new String(bytes, StandardCharsets.UTF_8);

System.out.println(decodedStr); // Java

}

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2. Using Apache Commons Library

Another option to encode a string into a byte array in Java is to use the StringUtils.getBytes(String, Charset) utility method from the org.apache.commons.lang3 package. This method converts a string to a byte array using the specified character set. This internally calls the String.getBytes(Charset) method, but handles null input gracefully. For example:

import org.apache.commons.lang3.StringUtils;

import java.nio.charset.Charset;

import java.util.Arrays;

public class Main

{

public static void main(String[] args) {

String str = "Java";

byte[] bytes = StringUtils.getBytes(str, Charset.defaultCharset());

System.out.println(Arrays.toString(bytes)); // [74, 97, 118, 97]

}

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We can also leverage the Apache Commons Codec StringUtils class to convert the String to and from bytes using the respective getBytes*() and newString*() utility methods from the org.apache.commons.codec.binary package.

import org.apache.commons.codec.binary.StringUtils;

import java.util.Arrays;

public class Main

{

public static void main(String[] args) {

String str = "Java";

byte[] bytes = StringUtils.getBytesUtf8(str);

System.out.println(Arrays.toString(bytes)); // [74, 97, 118, 97]

String decodedStr = StringUtils.newStringUtf8(bytes);

System.out.println(decodedStr); // Java

}

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3. Using `Charset.encode()` method

Use the Charset.encode() method, which is a method that can encode a string using a specific character set. This method returns a ByteBuffer that contains the encoded string. We can then convert the ByteBuffer to a byte array using the array() method. For example:

import java.nio.ByteBuffer;

import java.nio.charset.StandardCharsets;

import java.util.Arrays;

public class Main

{

public static void main(String[] args)

{

String str = "Java";

// encode a string using a specific character set

ByteBuffer buffer = StandardCharsets.UTF_8.encode(str);

// convert the ByteBuffer to a byte array

byte[] bytes = buffer.array();

System.out.println(Arrays.toString(bytes)); // [74, 97, 118, 97]

}

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That’s all about encoding a string into a byte array in Java.

Encode a String into a byte array in Java

1. Using getBytes() method

2. Using Apache Commons Library

3. Using Charset.encode() method

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1. Using `getBytes()` method

3. Using `Charset.encode()` method