Convert Unicode to UTF-8 in Java

Before moving onto their conversions, let us learn about Unicode and UTF-8.

Unicode is an international standard of character encoding which has the capability of representing a majority of written languages all over the globe. Unicode uses hexadecimal to represent a character. Unicode is a 16-bit character encoding system. The lowest value is \u0000 and the highest value is \uFFFF.

UTF-8 is a variable width character encoding. UTF-8 has the ability to be as condensed as ASCII but can also contain any Unicode characters with some increase in the size of the file. UTF stands for Unicode Transformation Format. The '8' signifies that it allocates 8-bit blocks to denote a character. The number of blocks needed to represent a character varies from 1 to 4.

In order to convert Unicode to UTF-8 in Java, we use the getBytes() method. The getBytes() method encodes a String into a sequence of bytes and returns a byte array.

Declaration - The getBytes() method is declared as follows.

public byte[] getBytes(String charsetName)

where charsetName is the specific charset by which the String is encoded into an array of bytes.

Let us see a program to convert Unicode to UTF-8 in Java using the getBytes() method.

Example

 Live Demo

public class Example {
   public static void main(String[] args) throws Exception {
      String str1 = "\u0000";
      String str2 = "\uFFFF";
      byte[] arr = str1.getBytes("UTF-8");
      byte[] brr = str2.getBytes("UTF-8");
      System.out.println("UTF-8 for \u0000");
      for(byte a: arr) {
         System.out.print(a);
      }
      System.out.println("\nUTF-8 for \uffff" );
      for(byte b: brr) {
         System.out.print(b);
      }
   }
}

Output

UTF-8 for \u0000
0
UTF-8 for \uffff
-17-65-65

Let us understand the above program. We have created two Strings.

String str1 = "\u0000";
String str2 = "\uFFFF";

String str1 is assigned \u0000 which is the lowest value in Unicode. String str2 is assigned \uFFFF which is the highest value in Unicode.

To convert them into UTF-8, we use the getBytes(“UTF-8”) method. This gives us an array of bytes as follows −

byte[] arr = str1.getBytes("UTF-8");
byte[] brr = str2.getBytes("UTF-8");

Then to print the byte array, we use an enhanced for loop as follows −

for(byte a: arr) {
   System.out.print(a);
}
for(byte b: brr) {
   System.out.print(b);
}