溢出菜单的 3 个点未显示在 ActionBar 中

Question

I am new to android and I am trying to create an overflow menu.

The 3 dots on the ActionBar are not showing (even after changing the app theme). After changing the app theme, it gets shown on the center of the screen "Android..CoordinatorLayout" how to get these 3 dots?

My menu_main.xml :

<menu 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"
    tools:context=".MainActivity">

    <item android:id="@+id/action_settings" 
        android:title="@string/action_settings"
        android:orderInCategory="100"
        app:showAsAction="always" />

    <item android:id="@+id/rtfm" 
        android:title="@string/action_settings"
        android:orderInCategory="100"
        app:showAsAction="never" />
</menu>

Answer 1

You should need something like this.

A menu.xml layout for the items under the res/menu directory.

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <item
        android:id="@+id/action_settings"
        android:title="@string/action_settings"
        app:showAsAction="never" />
    ...
</menu>

Then in your Activity you must include this methods.

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.menu, menu);

    return super.onCreateOptionsMenu(menu);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case R.id.action_settings:
            // Do something

            return true;
        default:
            return super.onOptionsItemSelected(item);
    }
}

Answer 2

You can use this trick at Activity's onCreate:

if (savedInstanceState == null) {
    //Show dots:
    try {
        ViewConfiguration config = ViewConfiguration.get(this);
        Field menuKeyField = ViewConfiguration.class.getDeclaredField("sHasPermanentMenuKey");

        if (menuKeyField != null) {
            menuKeyField.setAccessible(true);
            menuKeyField.setBoolean(config, false);
        }
    } catch (Exception ex) {
        // Ignore
    }

} else {
    //isResumed = true; ............. do something.....
}