How do I add 3 dot overflow menu on custom action bar for Oreo?

Question

I want to add overflow menu on my custom action bar. I know, I can add new settings activity but that's too confusing, and I wanted to know the exact code to add those.

I have seen few posts, but it was limited to older SDKs. As I am using custom layout for my action bar. Please help me so that code could work for Android 8.0 and for sdk's lower than that.

My code is as follows:

HomescreenActivity.java :-

@Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_homescreen);

        getSupportActionBar().setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);
        getSupportActionBar().setCustomView(R.layout.abs_layout);

   }

activity_homescreen.xml :-

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:background="@drawable/paper_planes_color_bg"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".HomescreenActivity">

   <android.support.v7.widget.RecyclerView
       android:layout_marginTop="15dp"
       android:id="@+id/recy_category"
       android:layout_width="match_parent"
       android:layout_height="match_parent">
   </android.support.v7.widget.RecyclerView>

</RelativeLayout>

abs_layout.xml :-

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <android.support.v7.widget.AppCompatTextView
        android:id="@+id/tvTitle"
        style="@style/TextAppearance.AppCompat.Widget.ActionBar.Title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:gravity="center"
        android:textColor="#FFFFFF" />

</LinearLayout>

Answer 1

Just override "onCreateOptionsMenu()" method, and mention your menu through "menu/your_menu_file.xml ", and to handle menu click listener override "onOptionsItemSelected" method

@Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.settings, menu);
        return true;
    }

Answer 2

custom_toolbar_layout :

include this layout in your activity xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:orientation="horizontal">


<TextView
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:layout_weight="1"
    android:text=""
    android:textColor="@color/toolbar_color"
    android:textSize="@dimen/_16sdp" />

<android.support.v7.widget.AppCompatImageView
    android:id="@+id/iv_back_toolbar"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:layout_gravity="center"
    android:padding="@dimen/_10sdp"
    app:srcCompat="@drawable/ic_more_vert_black_24dp" />
</LinearLayout>

ic_more_vert_black_24dp :

You can get 3 dots icon from android default vector or images assets. For this, Right Click on res > New > Vector Asset, then from Clipart you can get this icon as :

<vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:width="24dp"
    android:height="24dp"
    android:viewportWidth="24.0"
    android:viewportHeight="24.0">
<path
    android:fillColor="#FF000000"
    android:pathData="M12,8c1.1,0 2,-0.9 2,-2s-0.9,-2 -2,-2 -2,0.9 -2,2 0.9,2 2,2zM12,10c-1.1,0 -2,0.9 -2,2s0.9,2 2,2 2,-0.9 2,-2 -0.9,-2 -2,-2zM12,16c-1.1,0 -2,0.9 -2,2s0.9,2 2,2 2,-0.9 2,-2 -0.9,-2 -2,-2z"/>