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 java.util.ArrayList; import java.util.Iterator; import android.content.BroadcastReceiver; import android.content.Context; import android.content.DialogInterface; import android.content.Intent; import android.content.IntentFilter; import android.content.SharedPreferences; import android.os.Bundle; import android.preference.PreferenceManager; import android.util.Log; import android.view.View; import android.view.ViewGroup; import android.widget.ArrayAdapter; import android.widget.ImageView; import com.wimm.framework.app.AlertDialog; import com.wimm.framework.app.LauncherActivity; import com.wimm.framework.service.NetworkService; import com.wimm.framework.view.AdapterViewTray; import org.json.JSONObject; public class QRCodeKeeperActivity extends LauncherActivity implements JSONLoadTask.Listener, DialogInterface.OnClickListener { private ArrayList<Entry> entries = new ArrayList<Entry>(); private AdapterViewTray tray = null; private SharedPreferences prefs = null; private boolean noCanDo = false; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); prefs = PreferenceManager.getDefaultSharedPreferences(this); tray = (AdapterViewTray) findViewById(android.R.id.list); tray.setCanLoop(true); NetworkService network = new NetworkService(this); if (SyncService.iCanHasData(this)) { loadEntries(); } else { noCanDo = true; } if (SyncService.isSyncNeeded(this, prefs)) { if (network.isNetworkAvailable()) { startService(new Intent(this, SyncService.class)); } else { network.requestNetworkConnection(); } } if (noCanDo) { AlertDialog dlg = new AlertDialog(this); dlg.setButton(getText(R.string.close), this); dlg.setMessage(getText(R.string.no_can_do)); dlg.show(); } } @Override public void onResume() { super.onResume(); if (!noCanDo) { registerReceiver(statusReceiver, new IntentFilter(SyncService.ACTION_SYNC_STATUS)); } } @Override public void onPause() { if (!noCanDo) { unregisterReceiver(statusReceiver); } super.onPause(); } @SuppressWarnings("unchecked") @Override public void handleResult(JSONObject json) { entries.clear(); try { for (Iterator<String> i = json.keys(); i.hasNext();) { String title = i.next(); String url = json.getString(title); entries.add(new Entry(title, url)); } tray.setAdapter(new EntryAdapter()); } catch (Exception ex) { Log.e("QRCodeKeeper", "Exception interpreting JSON", ex); goBlooey(ex); } } @Override public void handleError(Exception ex) { Log.e("QRCodeKeeper", "Exception loading JSON", ex); goBlooey(ex); } @Override public void onClick(DialogInterface dialog, int which) { finish(); } private void loadEntries() { new JSONLoadTask(this, this).execute(SyncService.SYNC_LOCAL_FILE); } private void goBlooey(Exception ex) { AlertDialog dlg = new AlertDialog(this); dlg.setButton(getText(R.string.close), this); dlg.setMessage(ex.getMessage()); dlg.show(); } private final BroadcastReceiver statusReceiver = new BroadcastReceiver() { public void onReceive(Context context, Intent intent) { boolean isRunning = intent.getBooleanExtra(SyncService.KEY_STATUS, false); if (!isRunning) { loadEntries(); } } }; class EntryAdapter extends ArrayAdapter<Entry> { public EntryAdapter() { super(QRCodeKeeperActivity.this, R.layout.entry, R.id.title, entries); } @Override public View getView(int position, View convertView, ViewGroup parent) { View row = super.getView(position, convertView, parent); ImageView qrCode = (ImageView) row.findViewById(R.id.qrCode); try { File image = new File(getFilesDir(), getItem(position).getFilename()); new ImageLoadTask(qrCode).execute(image.getAbsolutePath()); } catch (Exception ex) { Log.e("QRCodeKeeper", "Exception interpreting JSON", ex); goBlooey(ex); } return (row); } } }