Get users text and display it in a text view in a different class

Question

I am creating a review page. When user clicks on the review stars in ClassOne.java it takes them to a different activity which is ClassTwo.java. When user writes their review and clicks on submit I want their review to go back to ClassOne.java and display it in the TextView under Reviews section. I have sumbit button in ClassTwo.java not shown in the image. This is what i have so far but I keep getting this error, "java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)'on a null object reference". How can i fix this problem?

ClassOne.java ClassTwo.java ClassTwo.java

public class ClassTwo extends Activity{

private TextView reviewDisplay;
private Button submitButton;
private EditText usersReview;

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

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

            Editable editTextReview = usersReview.getText();
            reviewDisplay.setText(editTextReview);
            Intent intent = new Intent(ClassTwo.this, ClassOne.class);
            startActivity(intent);
        }
    });