<FrameLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <TextView
      android:id="@+id/tv"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:layout_marginRight="6dp"
      android:background="@null"
      android:gravity="right|center_vertical"
      android:text="請輸入您想輸入的" />

    <EditText
      android:id="@+id/et"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:gravity="right|center_vertical" />
  </FrameLayout>

 et.addTextChangedListener(new TextWatcher() {
      @Override
      public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
      }

      @Override
      public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
        if (TextUtils.isEmpty(charSequence)) {
          tv.setVisibility(View.VISIBLE);
        } else {
          tv.setVisibility(View.GONE);
        }
      }

      @Override
      public void afterTextChanged(Editable editable) {
      }
    });