如何使用Eclipse创建非片段式Android应用程序？

我正在关注有关创建Android应用程序的教程，并且Eclipse生成了很多我现在不需要的代码。例如，它从ActionBarActivity扩展了MainActivity类，而我只希望它是Activity派生的类。

这是代码：

package com.example.helloworld;

import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
import android.util.Log;

public class MainActivity extends ActionBarActivity {

    String tag = "HelloWorld";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.d(tag, "onCreate() triggered!");

        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment()).commit();
        }
    }

    @Override
    public void onStart(){
        super.onCreate(null);
        Log.d(tag, "onStart()");
    }

    @Override
    public void onResume(){
        super.onResume();
        Log.d(tag, "onResume()");
    }

    @Override 
    public void onPause(){
        super.onPause();
        Log.d(tag, "Paused!");
    }

    @Override 
    public void onStop(){
        super.onStop();
        Log.d(tag, "onStop()");
    }

    @Override
    public void onDestroy(){
        super.onDestroy();
        Log.d(tag, "onDestroy()");
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {

        public PlaceholderFragment() {
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main, container,
                    false);
            return rootView;
        }
    }

}