public class StringEditor {
 
 public static void main(String[] args) throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException {

   String str1 = "Hello";
   String str2 = new String("Hello");
   String sub = str2.substring(3);
  
  
   // str1 is directly pointing to String in String pool but str2 is pointing to the object created in heap
   // which is having the value of 'Hello'. So if we make any change to 'Hello' in String pool, str2 value will
   // not be impacted. But if we point str2 to 'Hello' of String pool by using intern then value of str2 will be
   // impacted. intern() returns the string from the pool, so if we dont assign it to str2 then again value of str2
   // will not be impacted.
   str2 = str2.intern();
   System.out.println(str1 == str2);
  
   System.out.println("Current value of str1 & str2 : " + str1);
  
   Field fStr = String.class.getDeclaredField("value");
   fStr.setAccessible(true);
   char[] chr = (char[])fStr.get(str1);
   char[] suba = (char[])fStr.get(sub);
   // Value of suba printed below will depend on the jre being used to execute this file
   // prior to jre7 it will give whole value of the parent string str2, though it is using
   // only 2 of its characters causing the memory leak, but this behavior has been corrected
   // from jre7, so from jre7 it will give only 2 characters.
   System.out.println(Arrays.toString(suba));
    
   chr[1] = 'i';
   chr[2] = '\u0000';
   chr[3] = '\u0000';
   chr[4] = '\u0000';
  
   char[] newChar = new char[10];
   newChar[0] = 'I';
   newChar[1] = ' ';
   newChar[2] = 'A';
   newChar[3] = 'M';
   newChar[4] = ' ';
   newChar[5] = 'N';
   newChar[6] = 'I';
   newChar[7] = 'T';
   newChar[8] = 'I';
   newChar[9] = 'N';
  
   fStr.set(str1, newChar);
  
   System.out.println("After change value of str1 : " +str1);
   System.out.println(str2);
   System.out.println("Still str1 & str2 are equal : " + (str1==str2));
  
 }

}