String Handling Demo

StringDemo.java

/*
 * StringDemo.java
 *
 * String Handling.
 * - String is fixed and immutable class object.
 * - Strings are stored in Java heap memory.
 * - 
 *
 * Usage:
 *   javac StringDemo.java && java StringDemo
 */

class StringDemo {
  public static final String ANSI_RESET  = "\u001B[0m";
  public static final String ANSI_BLACK  = "\u001B[30m";
  public static final String ANSI_RED    = "\u001B[31m";
  public static final String ANSI_GREEN  = "\u001B[32m";
  public static final String ANSI_YELLOW = "\u001B[33m";
  public static final String ANSI_BLUE   = "\u001B[34m";
  public static final String ANSI_PURPLE = "\u001B[35m";
  public static final String ANSI_CYAN   = "\u001B[36m";
  public static final String ANSI_WHITE  = "\u001B[37m";

  public static void main(String args[]) {
    String s1 = "hello";
    String s2 = new String("hello");
    String s3 = "hello";

    s1.toUpperCase(); // String is fixed and immutable
    System.out.println(s1); // Output: hello

    s1 = s1.toUpperCase(); // s1 is replaced by the new object.
    System.out.println(s1); // Output: HELLO

    // Color test
    // It generally works for Unix shell prompts, 
    // however it doesn't work for Windows command prompt 
    // (although it does work for Cygwin).
    // See: http://stackoverflow.com/questions/5762491/how-to-print-color-in-console-using-system-out-println
    System.out.println(ANSI_RED + s1 + ANSI_RESET); // Output: HELLO

    // Compare the object references
    System.out.println(s1 == s2);

    String a1 = "hello";
    String a2 = "hello";
    String a3 = new String("hello");
    System.out.println(a1 == a3); // False, comparison of different objects.
    System.out.println(a1 == a2); // True, as "hello" is the same object.
  }

}