MainActivity.java

package com.simpleapps22.dholuo;

import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.viewpager.widget.ViewPager;

import com.google.android.material.tabs.TabLayout;

public class MainActivity extends AppCompatActivity {

    private final static String APP_PROJECT_NAME = "com.simpleapps22.dholuo";// Package Name

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Set the content of the activity to use the activity_main.xml layout file
        setContentView(R.layout.activity_main);

        // Find the view pager that will allow the user to swipe between fragments
        ViewPager viewPager = findViewById(R.id.viewpager);


        // Create an adapter that knows which fragment should be shown on each page
        CategoryAdapter adapter = new CategoryAdapter(MainActivity.this, getSupportFragmentManager());

        // Set the adapter onto the view pager
        viewPager.setAdapter(adapter);

        // Find the tab layout that shows the tabs
        TabLayout tabLayout = findViewById(R.id.tabs);

        // Connect the tab layout with the view pager. This will
        //   1. Update the tab layout when the view pager is swiped
        //   2. Update the view pager when a tab is selected
        //   3. Set the tab layout's tab names with the view pager's adapter's titles
        //      by calling onPageTitle()
        tabLayout.setupWithViewPager(viewPager);
    }

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

    @Override
    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
        switch (item.getItemId()) {

            case R.id.rateApp:

                Intent ratingsIntent = new Intent(Intent.ACTION_VIEW);
                ratingsIntent.setData(Uri.parse("market://details?id=" + APP_PROJECT_NAME));
                if (ratingsIntent.resolveActivity(getPackageManager()) != null) {
                    startActivity(ratingsIntent);
                }
                return true;

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