android new view,android

我在Button和EditText的以下代码中遇到上述错误.我只是不知道为什么会这样.如果你们能理解并告诉我这里到底出了什么问题,那就太好了.

import android.app.Activity;

import android.content.Intent;

import android.net.Uri;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.EditText;

public class Activity2 extends Activity {

public void onCreate(Bundle savedInstanceState)

{

super.onCreate(savedInstanceState);

setContentView(R.layout.activity2);

Button btn = (Button) findViewByID(R.id.btn_OK);

btn.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View v) {

Intent data = new Intent();

EditText txt_username = (EditText) findViewByID(R.id.txt_username);

data.setData(Uri.parse(txt_username.getText().toString()));

setResult(RESULT_OK, data);

finish();

}

});

}

}