Android - 致命异常主要错误

Question

我的任务是修改一个应用程序。我混淆了主要的错误。 主要错误在哪里？

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    ConfigurationBuilder cb = new ConfigurationBuilder();

    String consumerkey = "A";
    String consumersecret = "A";
    String token = "S";
    String tokensecret = "D";

    String nonce = "Vf";
    String signature = "D";
    String signaturemethod = "HMAC-SHA1";
    String timestamp = "2";

    {   
        cb.setDebugEnabled(true)
          .setOAuthConsumerKey(consumerkey)
          .setOAuthConsumerSecret(consumersecret)
          .setOAuthAccessToken(token)
          .setOAuthAccessTokenSecret(tokensecret);
    }

    //TwitterFactory tf = new TwitterFactory(cb.build());
    //Twitter twitter = tf.getInstance();

    // The factory instance is re-useable and thread safe.

//insert the appropriate consumer key and consumer secret here

    requestWindowFeature(Window.FEATURE_CUSTOM_TITLE);
    setContentView(R.layout.activity_main);

    getWindow().setFeatureInt(Window.FEATURE_CUSTOM_TITLE, R.layout.window_title);
    setContentView(R.layout.activity_main);

    pager = (ViewPager) MainActivity.this.findViewById(R.id.viewpager);

    imageView = (ImageView) findViewById(R.id.header);
    nameTextView = (TextView) findViewById(R.id.title_name);
    descTextView = (TextView) findViewById(R.id.description);
    pageDescription = (TextView) findViewById(R.id.pageDescription);
    pageDescription.setText("Timeline");
    // Initialize the pager

    adView = (AdView)findViewById(R.id.adView);
    adView.loadAd(new AdRequest());

    this.initialisePagingTimeline();
}

Android主要仅在OnCreate中？我是android的新手。如果不仅仅是OnCreate，它会让我给出很长的源代码（因为完整的源代码很长，所以我不能给出）。你能帮我解决我的问题吗？

我无法上传logcat错误图片，因为我的声誉仍在十岁以下。