/**
     * Returns a canonical representation for the string object.
     * <p>
     * A pool of strings, initially empty, is maintained privately by the
     * class {@code String}.
     * <p>
     * When the intern method is invoked, if the pool already contains a
     * string equal to this {@code String} object as determined by
     * the {@link #equals(Object)} method, then the string from the pool is
     * returned. Otherwise, this {@code String} object is added to the
     * pool and a reference to this {@code String} object is returned.
     * <p>
     * It follows that for any two strings {@code s} and {@code t},
     * {@code s.intern() == t.intern()} is {@code true}
     * if and only if {@code s.equals(t)} is {@code true}.
     * <p>
     * All literal strings and string-valued constant expressions are
     * interned. String literals are defined in section 3.10.5 of the
     * <cite>The Java&trade; Language Specification</cite>.
     *
     * @return  a string that has the same contents as this string, but is
     *          guaranteed to be from a pool of unique strings.
     */
    public native String intern();

    public static void main(String[] args) {
        String s = new String("1");
        s.intern();
        String s2 = "1";
        System.out.println(s == s2);

        String s3 = new String("1") + new String("1");
        s3.intern();

        String s4 = "11";
        System.out.println(s3 == s4);
    }

public static void main(java.lang.String[]);
  Code:
   Stack=4, Locals=3, Args_size=1
   0:   new     #2; //class java/lang/StringBuilder
   3:   dup
   4:   invokespecial   #3; //Method java/lang/StringBuilder."<init>":()V
   7:   new     #4; //class java/lang/String
   10:  dup
   11:  ldc     #5; //String 1
   13:  invokespecial   #6; //Method java/lang/String."<init>":(Ljava/lang/String;)V
   16:  invokevirtual   #7; //Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
   19:  new     #4; //class java/lang/String
   22:  dup
   23:  ldc     #5; //String 1
   25:  invokespecial   #6; //Method java/lang/String."<init>":(Ljava/lang/String;)V
   28:  invokevirtual   #7; //Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
   31:  invokevirtual   #8; //Method java/lang/StringBuilder.toString:()Ljava/lang/String;
   34:  astore_1
   35:  aload_1
   36:  invokevirtual   #9; //Method java/lang/String.intern:()Ljava/lang/String;
   39:  pop
   40:  ldc     #10; //String 11
   42:  astore_2
   43:  getstatic       #11; //Field java/lang/System.out:Ljava/io/PrintStream;
   46:  aload_1
   47:  aload_2
   48:  if_acmpne       55
   51:  iconst_1
   52:  goto    56
   55:  iconst_0
   56:  invokevirtual   #12; //Method java/io/PrintStream.println:(Z)V
   59:  return

public static void main(java.lang.String[]);
  flags: ACC_PUBLIC, ACC_STATIC
  Code:
    stack=4, locals=3, args_size=1
       0: new           #2                  // class java/lang/StringBuilder
       3: dup
       4: invokespecial #3                  // Method java/lang/StringBuilder."<init>":()V
       7: new           #4                  // class java/lang/String
      10: dup
      11: ldc           #5                  // String 1
      13: invokespecial #6                  // Method java/lang/String."<init>":(Ljava/lang/String;)V
      16: invokevirtual #7                  // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
      19: new           #4                  // class java/lang/String
      22: dup
      23: ldc           #5                  // String 1
      25: invokespecial #6                  // Method java/lang/String."<init>":(Ljava/lang/String;)V
      28: invokevirtual #7                  // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
      31: invokevirtual #8                  // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
      34: astore_1
      35: aload_1
      36: invokevirtual #9                  // Method java/lang/String.intern:()Ljava/lang/String;
      39: pop
      40: ldc           #10                 // String 11
      42: astore_2
      43: getstatic     #11                 // Field java/lang/System.out:Ljava/io/PrintStream;
      46: aload_1
      47: aload_2
      48: if_acmpne     55
      51: iconst_1
      52: goto          56
      55: iconst_0
      56: invokevirtual #12                 // Method java/io/PrintStream.println:(Z)V
      59: return