Question

I’m just writing little program which will count click and display it in a textview when you click button. Here is my code:

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.view.View.OnClickListener;


public class Vaje01Activity extends Activity {
    /** Called when the activity is first created. */

    EditText txtCount;
    Button btnCount;
    int count = 0;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        txtCount = (EditText)findViewById(R.id.textView1); 
        txtCount.setText(String.valueOf(count));
        btnCount = (Button)findViewById(R.id.button1);       

        btnCount.setOnClickListener(new OnClickListener() {
             public void onClick(View arg0) {
                count++;
                txtCount.setText(String.valueOf(count));
             }
          });

    }
}

So when I try to run this it gives me an unexpected error that it has stopped, but in code there are no errors.

Answer 1

There are really only a couple of possibilities here. One possibility is that your main.xml layout is missing an element with id textView1 or button1, in which case you are getting a NullPointerException. The other (and this is my guess) is that the element with id textView1 is declared in the XML as a TextView instead of an EditText, in which case you are getting a ClassCastException.