• Screen 1 has a textview and a button
• Button click will enter 2nd screen, then nothing
• Navigation back button (at the bottom) returns 1st screen

• vv_tvOut1
• vv_btnTo2

• Right Click Java -> New -> Activity -> Empty Activity
  
• Android Studio automatically generates Java+XML

• Leave it now
• Or change background color

• Leave it now

import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;

import com.example.a11_intent.databinding.ActivityMainBinding;
public class MainActivity extends AppCompatActivity {
    private ActivityMainBinding binding;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //setContentView(R.layout.activity_main);
        binding = ActivityMainBinding.inflate(getLayoutInflater());
        setContentView(binding.getRoot());

        binding.vvBtnTo2.setOnClickListener(
                new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        ////Context ctx =  MainActivity.this;
                        // need MainActivity.this since 'this' is new OnclickListener
                        Intent lv_it = new Intent(MainActivity.this, MySecondActivity.class);
                        startActivity(lv_it);
                    }
                });
    }
}

• Add a button vv_btnTo1
• Center it

• 1.Toolbar button at the top
• 2.Button
• 3.Navigation button at the buttom

public class MySecondActivity extends AppCompatActivity {
    protected void onCreate(Bundle savedInstanceState) {
		...
        if (getIntent() != null) {
            getSupportActionBar().setDisplayHomeAsUpEnabled(true);
            //getSupportActionBar().setDisplayShowHomeEnabled(true);
            getSupportActionBar().setTitle("Back to First");
        }

    }

    // Method 1 android.R.id.home:
    @Override
    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
        switch (item.getItemId()) {
            case android.R.id.home:
                Intent lv_it = new Intent(MySecondActivity.this, MainActivity.class);
                startActivity(lv_it);
                return true;
        }
        return super.onOptionsItemSelected(item);
    }
}	
	

	protected void onCreate(Bundle savedInstanceState) {
    ...
	    binding.vvBtnTo1.setOnClickListener(
                new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        Intent lv_it = new Intent(MySecondActivity.this, MainActivity.class);
                        startActivity(lv_it);
                    }
                });	

By Default The Button Has the Function	
No Code Needed	

    @Override
    public void onBackPressed() {
        Intent lv_it = new Intent(MySecondActivity.this, MainActivity.class);
        startActivity(lv_it);
    }
If we comment this out, then all 3 ways won't back	

    @Override
    public boolean onSupportNavigateUp() {
        Intent lv_it = new Intent(MySecondActivity.this, MainActivity.class);
        startActivity(lv_it);

        return true;
    }
*** However, if you comment out onOptionsItemSelected intent creation 2 lines
*** won't work
*** Why? if you comment out entire onOptionsItemSelected(), it works again
*** if you override onOptionsItemSelected, then onSupportNavigateUp will not be called.
*** https://stackoverflow.com/questions/18780112/onsupportnavigateup-not-called/45076058	

Remove everything	
	
        //// HERE https://developer.android.com/guide/navigation/navigation-custom-back
        // This callback will only be called when MyFragment is at least Started.
        OnBackPressedCallback callback = new OnBackPressedCallback(true /* enabled by default */) {
            @Override
            public void handleOnBackPressed() {
                // Handle the back button event
                //onBackPressed();
                getSupportActionBar().setTitle("Back");
                Intent lv_it = new Intent(MySecondActivity.this, MainActivity.class);
                startActivity(lv_it);
            }
        };
        getOnBackPressedDispatcher().addCallback(this, callback);
        // The callback can be enabled or disabled here or in handleOnBackPressed()	
	

public class SecondActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);

        if (getIntent() != null) {
           getSupportActionBar().setDisplayHomeAsUpEnabled(true);
           //getSupportActionBar().setDisplayShowHomeEnabled(true);
           getSupportActionBar().setTitle("Back to First");
        }

        //// HERE https://developer.android.com/guide/navigation/navigation-custom-back
        // This callback will only be called when MyFragment is at least Started.
        OnBackPressedCallback callback = new OnBackPressedCallback(true /* enabled by default */) {
            @Override
            public void handleOnBackPressed() {
                // Handle the back button event
                //onBackPressed();
                getSupportActionBar().setTitle("Back");
                Intent lv_it = new Intent(SecondActivity.this, MainActivity.class);
                startActivity(lv_it);
            }
        };
        getOnBackPressedDispatcher().addCallback(this, callback);
        // The callback can be enabled or disabled here or in handleOnBackPressed()
    }

    @Override
    public boolean onSupportNavigateUp() {
        onBackPressed();
        return true;
    }
}	
	

• Create 4 xml files in /res/anim -- anim_slide_in/out_left/right
• 1. anim_slide_in_left.xml

  <set xmlns:android="http://schemas.android.com/apk/res/android">
      <translate
          android:duration="400"
          android:fromXDelta="100%"
          android:toXDelta="0%" >
      </translate>
  </set
  

• 2. anim_slide_in_right.xml
• 3. anim_slide_out_left.xml
• 4. anim_slide_out_right.xml
• Right click res->Android Resource Folder select anim
  
• copy 4 files into res/anmi

...
  Intent lv_it = new Intent(MainActivity.this, MySecondActivity.class);
  startActivity(lv_it);
  overridePendingTransition(R.anim.anim_slide_in_left, R.anim.anim_slide_out_left);

private void cfp_navBack (boolean flag){
	...
    overridePendingTransition(R.anim.anim_slide_in_right, R.anim.anim_slide_out_right);
}

• Add a textview and edittext in main
• Screen 1 button click goes to Screen 2 with info
• Screen 2 also added a textview and shows Screen 1 edittext content
• Screen 2 back updates Screen 1 textview

has
	vv_tvOut1
	vv_btnTo2
add
	vv_etIn1

has
	vv_btnTo1	
add
	vv_tvOut2

	...
	Intent lv_it = new Intent(MainActivity.this, SecondActivity.class);
	lv_it.putExtra("StrArg", binding.vvEtIn1.getText().toString());
	startActivity(lv_it);
	overridePendingTransition(R.anim.anim_slide_in_left, R.anim.anim_slide_out_left);	

...
if (getIntent() != null) {
	getSupportActionBar().setDisplayHomeAsUpEnabled(true);
	//getSupportActionBar().setDisplayShowHomeEnabled(true);
	getSupportActionBar().setTitle("Back to First");

	Bundle extras = getIntent().getExtras();
	String lv_str = extras != null ? extras.getString("StrArg") : "Empty";
	binding.vvTvOut2.setText("You Typed - " + lv_str);
}

• Follow A11-Intent ver05 to create res/anim folder and copy 4 files
• Follow A11-Intent ver01 to create MyListDetailsActivity (java and xml)
• MainActivity.java pass MainActivity.this to MyRecyclerViewAdapter.java
• MyRecyclerViewAdapter.java create intent and pass OSName as String
• MyListDetailsActivity.java update textview and enable toolbar button to return

vv_tvSub 
centered and 24sp

change
lv_adapter = new MyRecyclerViewAdapter(lv_data01, lv_data02);
to 
lv_adapter = new MyRecyclerViewAdapter(lv_data01, lv_data02, this);
or
 lv_adapter = new MyRecyclerViewAdapter(lv_data01, lv_data02, MainActivity.this);

    private final ArrayList<String> mv_data01, mv_data02;
add
    Activity cv_activity;	

    public MyRecyclerViewAdapter(ArrayList<String> data01, ArrayList<String> data02, Activity activity) {
        mv_data01 = data01;
        mv_data02 = data02;
        cv_activity = activity;
    }
...
        holder.itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    Intent lv_it = new Intent(cv_activity, MyListDetailsActivity.class);
                    lv_it.putExtra("OSName",
                            (String) mv_data02.get(holder.getAdapterPosition()).toString());
                    cv_activity.startActivity(lv_it);
                    cv_activity.overridePendingTransition(R.anim.anim_slide_in_left, R.anim.anim_slide_out_left);
                }
            });
...

...
    @Override
    protected void onCreate(Bundle savedInstanceState) {
...
        if (getIntent() != null) {
            getSupportActionBar().setDisplayHomeAsUpEnabled(true);
            getSupportActionBar().setTitle("Back");

            Bundle extras = getIntent().getExtras();
            String lv_str = extras != null ? extras.getString("OSName") : "Empty";
            TextView lv_tv = (TextView) findViewById(R.id.vv_tvSub);
            lv_tv.setText("You Selected - " + lv_str);
        }
...

    @Override
    public boolean onSupportNavigateUp() {
        Intent lv_it = new Intent(MyListDetailsActivity.this, MainActivity.class);
        this.startActivity(lv_it);
        this.overridePendingTransition(R.anim.anim_slide_in_right, R.anim.anim_slide_out_right);
        return true;
    }
...