title: I need some help in Undo function in Java
body: <p>I write a Text Editor with Java , and  I want to  add Undo function to it </p>
  
  <p>but without UndoManager Class , I need to use a Data Structure like Stack or LinkedList but the Stack class in Java use Object parameters e.g : push(Object o) , Not Push(String s)
  I need some hints or links .
  Thanks</p>