Unicode System in Java

What is Unicode?

Unicode provides a unique number (called a code point) for every character in every language, including symbols, digits, and special characters. It supports over 143,000 characters across more than 150 modern and historic scripts.

• Code Point Range: Unicode code points range from U+0000 to U+10FFFF.
• Examples:
  • 'A': U+0041
  • 'अ': U+0905
  • '你': U+4F60

Why Unicode in Java?

Before Unicode, different systems used different encoding standards, such as ASCII or ISO-8859. These systems had limitations, particularly when representing non-English characters. Unicode solves these problems by providing a consistent encoding system.

Characteristics of Unicode in Java

1. Default Character Encoding:

   • Java uses Unicode to represent char data type and String objects.
   • Each char is 16 bits (2 bytes) in Java, based on the UTF-16 encoding scheme.

2. Wide Character Support:

   • Java can handle characters from multiple languages, symbols, and emojis.

3. Compatibility:

   • Unicode ensures that Java programs can be executed on any platform with consistent results.

How Java Implements Unicode

1. Using the char Data Type:

   • The char type in Java is a 16-bit Unicode character.
   • Example:

     
     public class UnicodeExample {
         public static void main(String[] args) {
             char letter = 'A'; // Unicode: U+0041
             char hindiChar = 'अ'; // Unicode: U+0905
             System.out.println("Letter: " + letter);
             System.out.println("Hindi Character: " + hindiChar);
         }
     }
     

2. Using Unicode Escapes:

   • Unicode characters can also be represented using escape sequences in the form uXXXX, where XXXX is the hexadecimal code point.
   • Example:

     
     public class UnicodeEscapeExample {
         public static void main(String[] args) {
             char letter = 'u0041'; // Unicode for 'A'
             char smiley = 'u263A'; // Unicode for ☺
             System.out.println("Letter: " + letter);
             System.out.println("Smiley: " + smiley);
         }
     }
     

Unicode Encoding Schemes

Java primarily uses the UTF-16 encoding scheme, which:

1. Encodes most common characters (Basic Multilingual Plane) in 16 bits.
2. Encodes supplementary characters using 4 bytes (2 code units).

Other Unicode encoding schemes include:

• UTF-8: Variable-length encoding (1–4 bytes) and backward compatible with ASCII.
• UTF-32: Fixed-length encoding (4 bytes for all characters).

Advantages of Unicode in Java

1. Global Language Support:

   • Enables applications to support multiple languages in a single program.
   • Example: A Java application can process text in English, Hindi, Chinese, and Arabic simultaneously.

2. Platform Independence:

   • Java’s Unicode support ensures consistent character representation across different platforms.

3. Ease of Use:

   • Built-in support for Unicode in char and String simplifies handling characters.

Examples of Unicode Usage

Example 1: Printing Unicode Characters

public class UnicodePrintExample {
    public static void main(String[] args) {
        System.out.println("English: Hello");
        System.out.println("Hindi: u0928u092Eu0938u094Du0924u0947");
        System.out.println("Chinese: u4F60u597D");
        System.out.println("Smiley: u263A");
    }
}

Output:

English: Hello
Hindi: नमस्ते
Chinese: 你好
Smiley: ☺

Example 2: Supplementary Characters

public class SupplementaryExample {
    public static void main(String[] args) {
        String emoji = "uD83DuDE00"; // Unicode for 😀
        System.out.println("Emoji: " + emoji);
    }
}

Key Points

1. UTF-16 Encoding: Java’s char and String are based on UTF-16.
2. Unicode Escapes: Use uXXXX format for specifying characters in code.
3. Global Compatibility: Unicode allows Java applications to handle text in any language.
4. Memory Efficiency: UTF-16 uses variable-length encoding for supplementary characters.