Elements of ArrayList of java, cloned, not reference

  String s = "haha";
  ArrayList x = new ArrayList();
  x.add(s);
  
  s = "changed";
  
  String y = (String)x.get(0);
  
  System.out.println(y); 

 

---------------------------------output

 haha

 

 

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just realize this. I thought it is just a reference pointer, but not.