Android synchronize a button on different pages

Question

I am fairly new to Android and java. I am trying to make an application with multiple pages that you can swipe through. I started from a ViewPager2 example that is using a RecyclerView. It has 2 layout files. A main one and a viewPager one that is used for all the different pages, but with a different background color and title.

I have added a switch button on the viewpager xml and want to synchronize this button so it has the same state on all pages. But it does not do that out of the box. It seems the switch is created again for each of the different pages and I don't know how to access them on the other pages when the button on the current page is being changed.

It seems like a very simple thing to do, but I cannot find how to do it. Below is the code for my 2 java files. Any help would be greatly appreciated.

public class MainActivity extends AppCompatActivity {

    ViewPager2 viewPager2;
    boolean continuous;

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

        viewPager2 = findViewById(R.id.viewPager2);
        viewPager2.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
            @Override
            public void onPageSelected (int position) {
                if (continuous == true) continuous = false;
                else continuous = true;
                int pos = position;
            }
        });

        List<String> list = new ArrayList<>();
        list.add("First Screen");
        list.add("Second Screen");
        list.add("Third Screen");
        list.add("Fourth Screen");

        viewPager2.setAdapter(new ViewPagerAdapter(this, list, viewPager2));

    }
}

public class ViewPagerAdapter extends RecyclerView.Adapter<ViewPagerAdapter.ViewHolder> {

    private List<String> mData;
    private LayoutInflater mInflater;
    private ViewPager2 viewPager2;


    private int[] colorArray = new int[]{android.R.color.black, android.R.color.holo_blue_dark, android.R.color.holo_green_dark, android.R.color.holo_red_dark};

    ViewPagerAdapter(Context context, List<String> data, ViewPager2 viewPager2) {
        this.mInflater = LayoutInflater.from(context);
        this.mData = data;
        this.viewPager2 = viewPager2;
    }


    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = mInflater.inflate(R.layout.item_viewpager, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        String animal = mData.get(position);
        holder.myTextView.setText(animal);
        holder.relativeLayout.setBackgroundResource(colorArray[position]);
    }

    @Override
    public int getItemCount() {
        return mData.size();
    }


    // stores and recycles views as they are scrolled off screen
    public class ViewHolder extends RecyclerView.ViewHolder {
        TextView myTextView;
        RelativeLayout relativeLayout;
        Button button;
        Switch switch2;

        ViewHolder(View itemView) {
            super(itemView);
            myTextView = itemView.findViewById(R.id.tvTitle);
            relativeLayout = itemView.findViewById(R.id.container);
            button = itemView.findViewById(R.id.btnToggle);
            switch2 = itemView.findViewById(R.id.switch2);

            button.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {

                    if(viewPager2.getOrientation() == ViewPager2.ORIENTATION_VERTICAL)
                    viewPager2.setOrientation(ViewPager2.ORIENTATION_HORIZONTAL);
                    else{
                        viewPager2.setOrientation(ViewPager2.ORIENTATION_VERTICAL);
                    }
                }
            });

            switch2.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    if (switch2.isChecked()) {
                        button.setEnabled(false);
                    } else {
                        button.setEnabled(true);
                    }
                }
            });
        }
    }
}

Answer 1

 <?xml version="1.0" encoding="utf-8"?>
 <androidx.constraintlayout.widget.ConstraintLayout 
   xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   android:id="@+id/container"
   android:layout_width="match_parent"
   android:layout_height="match_parent">

<Button
    android:id="@+id/login"
    android:layout_width="40dp"
    android:layout_height="40dp"
    android:layout_gravity="top|left"
    app:tint="@color/white"
    android:layout_margin="@dimen/small"
    android:layout_marginTop="@dimen/small"
    android:src="@drawable/ic_account_circle_24"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintHorizontal_bias="0.0"/>

  <androidx.viewpager2.widget.ViewPager2
    android:id="@+id/screen_viewpager"
    android:layout_width="0dp"
    android:layout_height="0dp"
    android:layout_marginBottom="8dp"
    app:layout_constraintBottom_toTopOf="@+id/tab_indicator"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

This will help if you want to place the button on each page you should add it to your activity file and then place it on the position of the view pager