AsyncTask Problem (App stürzt ab)

1public class OptionsActivity extends Activity {
2
3 private Button btnSave;
4 public EditText etKlasse;
5 public TextView tvAusgabe;
6
7 /** Called when the activity is first created. */
8 @Override
9 public void onCreate(Bundle savedInstanceState) {
10 super.onCreate(savedInstanceState);
11 setContentView(R.layout.options);
12
13 // TODO Auto-generated method stub
14
15 ActionBar actionBar = getActionBar();
16 if(actionBar != null){
17
18 String abTitel = getString(R.string.action_settings);
19
20 actionBar.setTitle(abTitel);
21 actionBar.setDisplayHomeAsUpEnabled(true);
22 }
23
24 btnSave = (Button) findViewById(R.id.btnOptionsSave);
25 etKlasse = (EditText) findViewById(R.id.etOptionsKlasse);
26 tvAusgabe = (TextView) findViewById(R.id.tvOptionsAusgabe);
27
28 btnSave.setOnClickListener(new View.OnClickListener() {
29 @Override
30 public void onClick(View v) {
31 // TODO Auto-generated method stub
32 String strEingabe = etKlasse.getText().toString();
33
34 if(TextUtils.isEmpty(strEingabe)){
35 Toast.makeText(OptionsActivity.this, "Bitte Abkürzung für deine Klasse eingeben", Toast.LENGTH_LONG).show();
36 }else{
37 new CheckKlassenID().execute(strEingabe);
38 }
39
40 }
41 });
42
43 }
44
45
46
47 @Override
48 public boolean onOptionsItemSelected(MenuItem item){
49
50 if(item.getItemId() == android.R.id.home){
51 onBackPressed();
52 }
53
54 return super.onOptionsItemSelected(item);
55 }
56
57}
58
59
60
61
62class CheckKlassenID extends AsyncTask<String, String, String> {
63
64 public TextView tvAusgabe;
65
66 @Override
67 protected String doInBackground(String... params) {
68 String klasse = params[0];
69 String quellcode = null;
70 URL url = null;
71 try {
72 url = new URL("LINK WEGEN FORUM RAUSGENOMMEN" + klasse);
73 String readLine = null;
74 String sResult = null;
75 BufferedReader buffReader = new BufferedReader (new InputStreamReader (url.openStream ()));
76 while ((readLine = buffReader.readLine ()) != null) {
77 if (sResult == null) {
78 sResult = readLine;
79 }
80 else {
81 sResult = sResult + readLine;
82 }
83 }
84 quellcode = sResult;
85 }
86 catch (MalformedURLException me) {
87 me.printStackTrace();
88 }
89 catch (IOException ioe) {
90 ioe.printStackTrace();
91 }
92
93 return quellcode;
94 }
95
96 @Override
97 protected void onPostExecute(String result) {
98
99 tvAusgabe.setText(result);
100
101 }
102
103 @Override
104 protected void onPreExecute() {
105 }
106
107
108}