You have two options, both should work:
a)
editText.setText("Your text");
editText.setSelection(editText.getText().length());
b)
editText.setText("");
editText.append("Your text");
You have two options, both should work:
a)
editText.setText("Your text");
editText.setSelection(editText.getText().length());
b)
editText.setText("");
editText.append("Your text");