How can I prevent null from displaying in the TextView?

Question

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();
        }
    });
}

Answer 1

Just surround your setText call with an if block:-

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

Answer 2

Change your content like below. Your getExtra syntaxs are wrong

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