code: package me.dm7.barcodescanner.zbar.sample;
  
  import android.app.AlertDialog;
  import android.app.Dialog;
  import android.content.DialogInterface;
  import android.os.Bundle;
  import android.support.v4.app.DialogFragment;
  
  public class MessageDialogFragment extends DialogFragment {
      public interface MessageDialogListener {
          public void onDialogPositiveClick(DialogFragment dialog);
      }
  
      private String mTitle;
      private String mMessage;
      private MessageDialogListener mListener;
  
      public void onCreate(Bundle state) {
          super.onCreate(state);
          setRetainInstance(true);
      }
  
      public static MessageDialogFragment newInstance(String title, String message, MessageDialogListener listener) {
          MessageDialogFragment fragment = new MessageDialogFragment();
          fragment.mTitle = title;
          fragment.mMessage = message;
          fragment.mListener = listener;
          return fragment;
      }
  
      @Override
      public Dialog onCreateDialog(Bundle savedInstanceState) {
          AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
          builder.setMessage(mMessage)
                  .setTitle(mTitle);
  
          builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
              public void onClick(DialogInterface dialog, int id) {
                  if(mListener != null) {
                      mListener.onDialogPositiveClick(MessageDialogFragment.this);
                  }
              }
          });
  
          return builder.create();
      }
  }
  