How do I clear the text in Android TextView?

Try this,

public class AndroidDemo extends Activity implements OnClickListener{
Button add, clear;
EditText text;
@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        add = (Button) findViewById(R.id.addBtn);
        clear = (Button) findViewById(R.id.clrBtn);
        text = (EditText) findViewById(R.id.display);
        add.setOnClickListener(this);
        clear.setOnClickListener(this);
        }
@Override
public void onClick(View v){
    if(v == add){
        text.setText(messages[new java.util.Random().nextInt(messages.length)]);
    }else if(v == clear){
        text.setText("");
    }
    }
  }

Yes it is. Your problem is related to the onClickListener.

 add.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(v == add){
                    text.setText(messages[new java.util.Random().nextInt(messages.length)]);
                }else if(v == clear){
                    text.setText("");
                }
            }
        });

in this case if(v == clear) is always false. You have to register a View.OnClickListener() for the clear view/button, or make your Activity implements View.OnClickListener and set for both the button this as setOnClickListener

To answer your question, I use this method in my apps. Instead of setting the text to (""), it clears the stored value using the getText().clear(); method. Personally, I use this because it looks more professional and makes proper use of the clear command in android.

clearButton.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    editText.getText().clear();
                }
            });

EDIT: The original post had the tag 'EditText', so I answered the question with that in mind. This works with EditText, With a TextView, just call textview.setText("");