Program: 162544
Project: 162544
Buggy source:
public void deleteFiles(ArrayList<Layoutelements> a,final Main b,List<Integer> pos,AppTheme appTheme){
  final MaterialDialog.Builder c=new MaterialDialog.Builder(b.getActivity());
  c.title(b.getResources().getString(R.string.confirm));
  String names="String_Node_Str";
  final ArrayList<BaseFile> todelete=new ArrayList<>();
  for (int i=0; i < pos.size(); i++) {
    todelete.add(a.get(pos.get(i)).generateBaseFile());
    names=names + "String_Node_Str" + (i + 1)+ "String_Node_Str"+ a.get(pos.get(i)).getTitle();
  }
  c.content(b.getResources().getString(R.string.questiondelete) + names);
  c.theme(appTheme.getMaterialDialogTheme());
  c.negativeText(b.getResources().getString(R.string.no));
  c.positiveText(b.getResources().getString(R.string.yes));
  c.positiveColor(Color.parseColor(b.fabSkin));
  c.negativeColor(Color.parseColor(b.fabSkin));
  c.callback(new MaterialDialog.ButtonCallback(){
    @Override public void onPositive(    MaterialDialog materialDialog){
      Toast.makeText(b.getActivity(),b.getResources().getString(R.string.deleting),Toast.LENGTH_SHORT).show();
      b.MAIN_ACTIVITY.mainActivityHelper.deleteFiles(todelete);
    }
    @Override public void onNegative(    MaterialDialog materialDialog){
    }
  }
);
  c.build().show();
}

Fixed version (ground truth):
public void deleteFiles(ArrayList<Layoutelements> a,final Main b,List<Integer> pos,AppTheme appTheme){
  final MaterialDialog.Builder c=new MaterialDialog.Builder(b.getActivity());
  c.title(b.getResources().getString(R.string.confirm));
  int fileCounter=0, dirCounter=0;
  final ArrayList<BaseFile> todelete=new ArrayList<>();
  StringBuilder dirNames=new StringBuilder();
  StringBuilder fileNames=new StringBuilder();
  for (int i=0; i < pos.size(); i++) {
    todelete.add(a.get(pos.get(i)).generateBaseFile());
    if (a.get(pos.get(i)).isDirectory())     dirNames.append("String_Node_Str").append(++dirCounter).append("String_Node_Str").append(a.get(pos.get(i)).getTitle());
 else     fileNames.append("String_Node_Str").append(++fileCounter).append("String_Node_Str").append(a.get(pos.get(i)).getTitle()).append("String_Node_Str").append(a.get(pos.get(i)).getSize()).append("String_Node_Str");
  }
  String titleFiles=b.getResources().getString(R.string.title_files);
  String titleDirs=b.getResources().getString(R.string.title_dirs);
  if (fileNames.length() == 0)   c.content(b.getResources().getString(R.string.questiondelete) + "String_Node_Str" + "String_Node_Str"+ titleDirs+ "String_Node_Str"+ dirNames);
 else   if (dirNames.length() == 0)   c.content(b.getResources().getString(R.string.questiondelete) + "String_Node_Str" + "String_Node_Str"+ titleFiles+ "String_Node_Str"+ fileNames);
 else   c.content(b.getResources().getString(R.string.questiondelete) + "String_Node_Str" + "String_Node_Str"+ titleDirs+ "String_Node_Str"+ dirNames+ "String_Node_Str"+ "String_Node_Str"+ titleFiles+ "String_Node_Str"+ fileNames);
  c.theme(appTheme.getMaterialDialogTheme());
  c.negativeText(b.getResources().getString(R.string.no));
  c.positiveText(b.getResources().getString(R.string.yes));
  c.positiveColor(Color.parseColor(b.fabSkin));
  c.negativeColor(Color.parseColor(b.fabSkin));
  c.callback(new MaterialDialog.ButtonCallback(){
    @Override public void onPositive(    MaterialDialog materialDialog){
      Toast.makeText(b.getActivity(),b.getResources().getString(R.string.deleting),Toast.LENGTH_SHORT).show();
      b.MAIN_ACTIVITY.mainActivityHelper.deleteFiles(todelete);
    }
    @Override public void onNegative(    MaterialDialog materialDialog){
    }
  }
);
  c.build().show();
}