mEditText = ((EditText)findViewById(R.id.editText));//创建PerformEdit，一定要传入不为空的EditTextmPerformEdit =newPerformEdit(mEditText);mPerformEdit.setDefaultText("这是初始值,不做撤销记录");

//撤销mPerformEdit.undo();//重做mPerformEdit.redo();//清除历史mPerformEdit.clearHistory();