Display the Message

1. In the res/layout directory, edit the content_display_message.xml file.

2. Add an android:id attribute to the RelativeLayout. You need this attribute to reference the object from your app code.

   < RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   ...
   android:id="@+id/content">
   </RelativeLayout>
   

3. Switch back to editing DisplayMessageActivity.java.

4. In the onCreate() method, create a TextView object.

   TextView textView = new TextView(this);
   

5. Set the text size and message with setText().

   textView.setTextSize(40);
   textView.setText(message);
   

6. Add the TextView to the RelativeLayout identified by R.id.content.

   RelativeLayout layout = (RelativeLayout) findViewById(R.id.content);
   layout.addView(textView);
   

7. At the top of the file, import the TextView class.

   In Android Studio, press Alt + Enter (option + return on Mac) to import missing classes.

The complete onCreate() method for DisplayMessageActivity now looks like this:

@Override
protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.activity_display_message);
   Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
   setSupportActionBar(toolbar);

   FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
   fab.setOnClickListener(new View.OnClickListener() {
       @Override
       public void onClick(View view) {
           Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                   .setAction("Action", null)
                   .show();
       }
   });
   getSupportActionBar().setDisplayHomeAsUpEnabled(true);

   Intent intent = getIntent();
   String message = intent.getStringExtra(MyActivity.EXTRA_MESSAGE);
   TextView textView = new TextView(this);
   textView.setTextSize(40);
   textView.setText(message);

   RelativeLayout layout = (RelativeLayout) findViewById(R.id.content);
   layout.addView(textView);

You can now run the app. When it opens, type a message in the text field, and click Send. The second activity replaces the first one on the screen, showing the message you entered in the first activity.