Java tutorial
/*** Copyright (c) 2012 CommonsWare, LLC Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0. Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. From _The Busy Coder's Guide to Advanced Android Development_ http://commonsware.com/AdvAndroid */ package com.commonsware.android.qrck; import java.io.File; import android.content.Context; import android.os.AsyncTask; import org.json.JSONObject; public class JSONLoadTask extends AsyncTask<String, Void, JSONObject> { private Context ctxt = null; private Listener listener = null; private Exception ex = null; public JSONLoadTask(Context ctxt, Listener listener) { this.ctxt = ctxt; this.listener = listener; } @Override public JSONObject doInBackground(String... path) { JSONObject json = null; try { String fn = path[0]; if (new File(ctxt.getFilesDir(), fn).exists()) { json = AppUtils.load(ctxt, path[0]); } } catch (Exception ex) { this.ex = ex; } return (json); } @Override protected void onPostExecute(JSONObject json) { if (listener != null) { if (json != null) { listener.handleResult(json); } if (ex != null) { listener.handleError(ex); AppUtils.cleanup(ctxt); } } } public interface Listener { void handleResult(JSONObject json); void handleError(Exception ex); } }