Confused with NullPointerException - nullpointerexception

Question

I know that i am probably missing something simple but i am getting this error when i try to load my second activity and i have no idea why, I understand (Or iv'e been told) That it happens when your code doesn't point to anything, But iv'e checked it and it points to the correct location.
ResultText
package com.example.mdpmk1;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class ResultText extends Activity {
Button button;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addListenerOnButton();
//Points /\
}
public void addListenerOnButton() {
final Context context = this;
button = (Button) findViewById(R.id.returnHome);
button.setOnClickListener(new OnClickListener() {
//Points /\
#Override
public void onClick(View arg0) {
Intent intent = new Intent(context, MainActivity.class);
startActivity(intent);
}
});
String result=getIntent().getStringExtra("resultText");
setContentView(R.layout.result_text);
TextView tv=new TextView(this);
tv.setTextSize(20);
String str=result;
tv.setText(str);
setContentView(tv);
}
}
If you require any more of the files feel free to ask.
Sorry if its a noob question and thanks for the help in advance.

Answer 1

call setContentView(R.layout.result_text); before calling addListenerOnButton();
Like:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.result_text);
addListenerOnButton();
}