How can I prevent null from displaying in the TextView?

Very new to Android, and I'm honestly stumped by this.

So I have my MainActivity receiving some strings from a second activity, CallAnActivity.

I've made an intent to pass the strings back to the main activity, and they are displayed in a TextView. But before I enter any information, I would like for this text view to contain nothing and look blank.

But when the MainActivity is first launched, the text view, displayMessageActivity, is displaying multiple null values. As there are three strings being sent, it just repeats the word null three times.

The code for the MainActivity is:

    //callAnActivityButton to open second activity of app
    Button callAnActivityButton = findViewById(R.id.callActivityButton);
    callAnActivityButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick( View v ) {
            Intent intent = new Intent(MainActivity.this, CallAnActivity.class);
            startActivity(intent);
        }
    });

    Intent intent = getIntent();
    String emailAddress = intent.getStringExtra("emailAddress") + "\n";
    String emailSubject = intent.getStringExtra("emailSubject") + "\n";
    String emailBody = intent.getStringExtra("emailBody");

    //TextView to display text from second activity
    TextView displayMessageText = findViewById(R.id.displayMessageText);
    displayMessageText.setText(emailAddress + emailSubject + emailBody);

The code for the second activity, CallAnActivity, is:

    public void sendText(){

    String emailAddress = mEditTextAddress.getText().toString();
    String emailSubject = mEditTextSubject.getText().toString();
    String emailBody = mEditTextBody.getText().toString();

    Intent intent = new Intent(CallAnActivity.this, MainActivity.class);
    intent.putExtra("emailAddress", emailAddress);
    intent.putExtra("emailSubject", emailSubject);
    intent.putExtra("emailBody", emailBody);
    startActivityForResult(intent, REQUEST_CODE);
}

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

    mEditTextAddress = findViewById(R.id.emailAddressText);
    mEditTextSubject = findViewById(R.id.emailSubjectText);
    mEditTextBody = findViewById(R.id.emailBodyText);

    Button sendTextButton = findViewById(R.id.sendMailButton);
    sendTextButton.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick (View v) {
            sendText();
        }
    });
}

Just surround your setText call with an if block:-

if (intent.getStringExtra("emailAddress") != null) {
    displayMessageText.setText(emailAddress + emailSubject + emailBody);
}