setOnFocusChangeListener 在 Android 中如何工作？

Question

I have designed a simple Android Application to test how setOnFocusChangeListener works.

The Java Code:

public class MainActivity extends AppCompatActivity {
    TextView tv;
    EditText et;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tv = findViewById(R.id.textView);
        et = findViewById(R.id.edittext);
        et.setOnFocusChangeListener(new View.OnFocusChangeListener() {
            @Override
            public void onFocusChange(View view, boolean b) {
                if (b) {
                    tv.setText("Edit Text is focused!!");
                }
                else {
                    tv.setText("You stopped focussing on editText");
                }
            }
        });
    }
}

The XML Code:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:orientation="vertical">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Nothing happened"
        android:textSize="30sp"
        android:gravity="center"
        android:id="@+id/textView" />
    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:hint="Write here!!!"
        android:id="@+id/edittext" />
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Click Me!!" />

</LinearLayout>

But when I click on the edit text to write something, Edit Text is focused.! and displayed on the text view.

After stopping the focus, the EditText is never displayed on screen, even when I click anywhere else on the screen or on a button. I would like to know when the else part of onFocusChange will be displayed?

Answer 1

I guess it is cause the editText is never leaving the focus.

On the GUI editor or XML, there is a property named "focusOnTouch" which editText Views have on true by default that let you get the focus for the editText, but if there is no other view with that property on true too, no view could get the focus.

That property exists for every View, set it to true for each View you want to consider to get the focus when clicking, otherwise, the focus won't be passed to other views like your textView or button.