Program: 39746
Project: 39746
Buggy source:
@Override protected void onCreate(Bundle savedInstanceState){
  super.onCreate(savedInstanceState);
  task=new Task(this.getApplicationContext());
  usernameFileEditText=(EditText)findViewById(R.id.username);
  if (Config.username.length() < 3)   Config.username=this.getApplicationContext().getSharedPreferences("String_Node_Str",Context.MODE_PRIVATE).getString("String_Node_Str","String_Node_Str");
  if (Config.username.length() > 3) {
    usernameFileEditText.setText(Config.username);
  }
  setContentView(R.layout.activity_main);
  task.testRoot();
  Config.Context=this.getApplicationContext();
  ((Button)findViewById(R.id.launch_button)).setOnClickListener(new View.OnClickListener(){
    @Override public void onClick(    View v){
      usernameFileEditText=(EditText)findViewById(R.id.username);
      Config.username=usernameFileEditText.getText().toString();
      SharedPreferences.Editor editor=Config.Context.getSharedPreferences("String_Node_Str",Context.MODE_PRIVATE).edit();
      editor.putString("String_Node_Str",Config.username);
      editor.commit();
      ((Button)findViewById(R.id.launch_button)).setText(R.string.exporting_sns);
      ((Button)findViewById(R.id.launch_button)).setEnabled(false);
      new RunningTask().execute();
    }
  }
);
  TextView descriptionHtmlTextView=(TextView)findViewById(R.id.description_html_textview);
  descriptionHtmlTextView.setMovementMethod(LinkMovementMethod.getInstance());
  descriptionHtmlTextView.setText(Html.fromHtml(getResources().getString(R.string.description_html)));
}

Fixed version (ground truth):
@Override protected void onCreate(Bundle savedInstanceState){
  super.onCreate(savedInstanceState);
  task=new Task(this.getApplicationContext());
  usernameFileEditText=(EditText)findViewById(R.id.username);
  if (Config.username.length() < 3)   Config.username=this.getApplicationContext().getSharedPreferences("String_Node_Str",Context.MODE_PRIVATE).getString("String_Node_Str","String_Node_Str");
  if (Config.username.length() > 3 && Config.username != null) {
    CharSequence u=Config.username;
    Log.d("String_Node_Str","String_Node_Str" + u);
  }
  setContentView(R.layout.activity_main);
  task.testRoot();
  Config.Context=this.getApplicationContext();
  ((Button)findViewById(R.id.launch_button)).setOnClickListener(new View.OnClickListener(){
    @Override public void onClick(    View v){
      usernameFileEditText=(EditText)findViewById(R.id.username);
      Config.username=usernameFileEditText.getText().toString();
      SharedPreferences.Editor editor=Config.Context.getSharedPreferences("String_Node_Str",Context.MODE_PRIVATE).edit();
      editor.putString("String_Node_Str",Config.username);
      editor.commit();
      ((Button)findViewById(R.id.launch_button)).setText(R.string.exporting_sns);
      ((Button)findViewById(R.id.launch_button)).setEnabled(false);
      new RunningTask().execute();
    }
  }
);
  TextView descriptionHtmlTextView=(TextView)findViewById(R.id.description_html_textview);
  descriptionHtmlTextView.setMovementMethod(LinkMovementMethod.getInstance());
  descriptionHtmlTextView.setText(Html.fromHtml(getResources().getString(R.string.description_html)));
}