两个一起设的时候就会互相调用递归下去。建议在beforeTextChanged中删除另一个EditText的监听，然后在onTextChanged进行处理，最后在afterTextChanged重新将另一EditText的监听设回。

同样的问题：见https://segmentfault.com/q/1010000005999377

  et1.addTextChangedListener(watcher1);

  et2.addTextChangedListener(watcher2);

  private TextWatcher1 watcher1 = new TextWatcher1();

  private TextWatcher2 watcher2 = new TextWatcher2();

  private class TextWatcher1 implements TextWatcher {

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
      et2.removeTextChangedListener(watcher2);
    }

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
      et2.setText(s);
    }

    @Override
    public void afterTextChanged(Editable s) {
      et2.addTextChangedListener(watcher2);
    }
  }

  private class TextWatcher2 implements TextWatcher {

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
      et1.removeTextChangedListener(watcher1);
    }

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
      et1.setText(s + "元");
    }

    @Override
    public void afterTextChanged(Editable s) {
      et1.addTextChangedListener(watcher1);
    }
  }