您好，我是 android 开发新手，这是我的第一个应用程序。我尝试连接到数据库，但是当模拟器启动时，应用程序意外停止。eclipse中的一切都很好，但是当我运行模拟器时它会停止。这是代码：
public class Antallaktika extends Activity {
JSONArray jArray;
String result = null;
InputStream is = null;
StringBuilder sb = null;
ArrayList<String> al = new ArrayList<String>();
ArrayList<String> al1 = new ArrayList<String>();
ArrayList<String> al2 = new ArrayList<String>();
String targetname;
String targetsku;
String targetprice;
int responseCode;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.antallaktika);
setTitle("Ανταλλακτικά");
try {
URL url = new URL("http://machina.gr/antallaktika.php");
URLConnection connection = url.openConnection();
connection.setConnectTimeout(2000);
HttpURLConnection httpConnection = (HttpURLConnection) connection;
responseCode = httpConnection.getResponseCode();
}
catch (Exception e) {}
try{
if(isNetworkAvailable()==true && responseCode == HttpURLConnection.HTTP_OK){
new LoadData().execute();
}
else{
AlertDialog.Builder ad=new AlertDialog.Builder(this);
ad.setMessage("No Internet Connection available!!!");
ad.show();
}
}
catch(Exception e){
}
}
public class LoadData extends AsyncTask<Void, Void, Void> {
private ProgressDialog progressDialog;
@Override
// can use UI thread here
protected void onPreExecute() {
this.progressDialog = ProgressDialog.show(Antallaktika.this, ""," Loading...");
}
@Override
protected void onPostExecute(final Void unused) {
this.progressDialog.dismiss();
try{
ListView listview = (ListView) findViewById(R.id.listView1);
this.progressDialog.dismiss();
listview.setAdapter(new DataAdapter(Antallaktika.this,al.toArray(new String[al.size()]),al1.toArray(new String[al1.size()]),al2.toArray(new String[al2.size()])));
}
catch(Exception e){
Toast.makeText(getApplicationContext(), e.toString(), Toast.LENGTH_LONG).show();
}
}
@Override
protected Void doInBackground(Void... params) {
// TODO Auto-generated method stub
// HTTP post
try {
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
HttpClient httpclient = new DefaultHttpClient();
try{
HttpPost httppost = new HttpPost("http://machina.gr/antallaktika.php");
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
}
catch(Exception e){
Toast.makeText(getApplicationContext(), e.toString(), Toast.LENGTH_LONG).show();
}
//buffered reader
try{
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 80);
sb = new StringBuilder();
sb.append(reader.readLine() + "\n");
String line = "0";
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
result = sb.toString();
}
catch(Exception e){
Toast.makeText(getApplicationContext(), e.toString(), Toast.LENGTH_LONG).show();
}
try{
jArray = new JSONArray(result);
JSONObject json_data = null;
for (int i = 0; i < jArray.length(); i++) {
json_data = jArray.getJSONObject(i);
targetname=json_data.getString("targetname");
targetsku=json_data.getString("targetsku");
targetprice = json_data.getString("targetprice");
al.add(targetname);
al1.add(targetsku);
al2.add(targetprice);
}
}
catch(JSONException e){
Toast.makeText(getApplicationContext(), e.toString(), Toast.LENGTH_LONG).show();
}
} catch (ParseException e) {
// Log.e("log_tag", "Error in http connection" + e.toString());
Toast.makeText(getApplicationContext(), e.toString(), Toast.LENGTH_LONG).show();
}
catch (Exception e) {
// Log.e("log_tag", "Error in http connection" + e.toString());
Toast.makeText(getApplicationContext(), e.toString(), Toast.LENGTH_LONG).show();
}
return null;
}
}
public boolean isNetworkAvailable() {
ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = cm.getActiveNetworkInfo();
// if no network is available networkInfo will be null, otherwise check
// if we are connected
if (networkInfo != null && networkInfo.isConnected()) {
// Log.i("net status:", "Online...!!!");
return true;
}
// Log.i("net status:", "offline...!!!");
return false;
}
}
logcat 是：
08-01 20:51:36.042: E/AndroidRuntime(375): FATAL EXCEPTION: AsyncTask #1
08-01 20:51:36.042: E/AndroidRuntime(375): java.lang.RuntimeException: An error occured while executing doInBackground()
08-01 20:51:36.042: E/AndroidRuntime(375): at android.os.AsyncTask$3.done(AsyncTask.java:200)
08-01 20:51:36.042: E/AndroidRuntime(375): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:274)
08-01 20:51:36.042: E/AndroidRuntime(375): at java.util.concurrent.FutureTask.setException(FutureTask.java:125)
08-01 20:51:36.042: E/AndroidRuntime(375): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:308)
08-01 20:51:36.042: E/AndroidRuntime(375): at java.util.concurrent.FutureTask.run(FutureTask.java:138)
08-01 20:51:36.042: E/AndroidRuntime(375): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088)
08-01 20:51:36.042: E/AndroidRuntime(375): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581)
08-01 20:51:36.042: E/AndroidRuntime(375): at java.lang.Thread.run(Thread.java:1019)
08-01 20:51:36.042: E/AndroidRuntime(375): Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
08-01 20:51:36.042: E/AndroidRuntime(375): at android.os.Handler.<init>(Handler.java:121)
08-01 20:51:36.042: E/AndroidRuntime(375): at android.widget.Toast.<init>(Toast.java:68)
08-01 20:51:36.042: E/AndroidRuntime(375): at android.widget.Toast.makeText(Toast.java:231)
08-01 20:51:36.042: E/AndroidRuntime(375): at com.pythagoras.machina.gr.Antallaktika$LoadData.doInBackground(Antallaktika.java:161)
08-01 20:51:36.042: E/AndroidRuntime(375): at com.pythagoras.machina.gr.Antallaktika$LoadData.doInBackground(Antallaktika.java:1)
08-01 20:51:36.042: E/AndroidRuntime(375): at android.os.AsyncTask$2.call(AsyncTask.java:185)
08-01 20:51:36.042: E/AndroidRuntime(375): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306)
08-01 20:51:36.042: E/AndroidRuntime(375): ... 4 more
08-01 20:51:37.142: E/WindowManager(375): Activity com.pythagoras.machina.gr.Antallaktika has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@405312b8 that was originally added here
08-01 20:51:37.142: E/WindowManager(375): android.view.WindowLeaked: Activity com.pythagoras.machina.gr.Antallaktika has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@405312b8 that was originally added here
08-01 20:51:37.142: E/WindowManager(375): at android.view.ViewRoot.<init>(ViewRoot.java:258)
08-01 20:51:37.142: E/WindowManager(375): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:148)
08-01 20:51:37.142: E/WindowManager(375): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
08-01 20:51:37.142: E/WindowManager(375): at android.view.Window$LocalWindowManager.addView(Window.java:424)
08-01 20:51:37.142: E/WindowManager(375): at android.app.Dialog.show(Dialog.java:241)
08-01 20:51:37.142: E/WindowManager(375): at android.app.ProgressDialog.show(ProgressDialog.java:107)
08-01 20:51:37.142: E/WindowManager(375): at android.app.ProgressDialog.show(ProgressDialog.java:90)
08-01 20:51:37.142: E/WindowManager(375): at android.app.ProgressDialog.show(ProgressDialog.java:85)
08-01 20:51:37.142: E/WindowManager(375): at com.pythagoras.machina.gr.Antallaktika$LoadData.onPreExecute(Antallaktika.java:85)
08-01 20:51:37.142: E/WindowManager(375): at android.os.AsyncTask.execute(AsyncTask.java:391)
08-01 20:51:37.142: E/WindowManager(375): at com.pythagoras.machina.gr.Antallaktika.onCreate(Antallaktika.java:67)
08-01 20:51:37.142: E/WindowManager(375): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
08-01 20:51:37.142: E/WindowManager(375): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
08-01 20:51:37.142: E/WindowManager(375): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
08-01 20:51:37.142: E/WindowManager(375): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
08-01 20:51:37.142: E/WindowManager(375): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
08-01 20:51:37.142: E/WindowManager(375): at android.os.Handler.dispatchMessage(Handler.java:99)
08-01 20:51:37.142: E/WindowManager(375): at android.os.Looper.loop(Looper.java:130)
08-01 20:51:37.142: E/WindowManager(375): at android.app.ActivityThread.main(ActivityThread.java:3683)
08-01 20:51:37.142: E/WindowManager(375): at java.lang.reflect.Method.invokeNative(Native Method)
08-01 20:51:37.142: E/WindowManager(375): at java.lang.reflect.Method.invoke(Method.java:507)
08-01 20:51:37.142: E/WindowManager(375): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
08-01 20:51:37.142: E/WindowManager(375): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
08-01 20:51:37.142: E/WindowManager(375): at dalvik.system.NativeStart.main(Native Method)