私は自分のアプリケーションで別の問題を抱えていますが、今回は私のスタックトレースが別のことを言っているので、誰かがこの問題を解決してくれることを願っていました. 何が悪いのか、それを修正するために何ができるのかを教えてくれる人が必要です.
07-26 13:40:26.983: E/AndroidRuntime(837): FATAL EXCEPTION: main
07-26 13:40:26.983: E/AndroidRuntime(837): java.lang.NullPointerException
07-26 13:40:26.983: E/AndroidRuntime(837): at com.theproblemsolver.asynctask.onPostExecute(MainActivity.java:72)
07-26 13:40:26.983: E/AndroidRuntime(837): at com.theproblemsolver.asynctask.onPostExecute(MainActivity.java:1)
07-26 13:40:26.983: E/AndroidRuntime(837): at android.os.AsyncTask.finish(AsyncTask.java:631)
07-26 13:40:26.983: E/AndroidRuntime(837): at android.os.AsyncTask.access$600(AsyncTask.java:177)
07-26 13:40:26.983: E/AndroidRuntime(837): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
07-26 13:40:26.983: E/AndroidRuntime(837): at android.os.Handler.dispatchMessage(Handler.java:99)
07-26 13:40:26.983: E/AndroidRuntime(837): at android.os.Looper.loop(Looper.java:137)
07-26 13:40:26.983: E/AndroidRuntime(837): at android.app.ActivityThread.main(ActivityThread.java:5041)
07-26 13:40:26.983: E/AndroidRuntime(837): at java.lang.reflect.Method.invokeNative(Native Method)
07-26 13:40:26.983: E/AndroidRuntime(837): at java.lang.reflect.Method.invoke(Method.java:511)
07-26 13:40:26.983: E/AndroidRuntime(837): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
07-26 13:40:26.983: E/AndroidRuntime(837): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
07-26 13:40:26.983: E/AndroidRuntime(837): at dalvik.system.NativeStart.main(Native Method)
07-26 13:40:31.994: E/Trace(864): error opening trace file: No such file or directory (2)
主な活動
public class MainActivity extends Activity {
EditText et;
Button getanswer;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button getanswer = (Button) findViewById(R.id.button1);
getanswer.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
new asynctask().execute();
Intent i = new Intent(MainActivity.this, ListView.class);
startActivity(i);
}
//protected void launchNewActivity(){
//startActivity(new Intent(MainActivity.this, ListView.class));
});
}
}
class asynctask extends AsyncTask<String, Void, JSONObject> {
private static final String TAG_RESULTS = "ResultsSet";
private static final String TAG_SUBJECT = "Subject";
private static final String TAG_NUMANSWERS = "NumAnswers";
private static final String TAG_QUESTION = "Question";
private static final String TAG_QUESTION_CONTENT = "Content";
private static final String TAG_QUESTION_CHOSENANSWER = "ChosenAnswer";
private static final String TAG_QUESTION_ANSWERS = "Answers";
public JSONArray json;
@Override
protected JSONObject doInBackground(String... params) {
JSONParsser jParser = new JSONParsser();
String URI = "http://example.com/json";
JSONObject json = jParser.getJSONFromURI(URI);
return json ;
}{ }
@Override
protected void onPostExecute(JSONObject json) {
JSONArray ResultsSet = null ; {
try {
ResultsSet = json.getJSONArray(TAG_RESULTS);
} catch (JSONException e) {
e.printStackTrace();
}
return;
}}
}
ListView アクティビティ
public class ListView extends ListActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//setContentView(R.layout.listview);
//protected void doInBackground(String... params) {
JSONParsser jParser = new JSONParsser();
String URI = "http://example.com/json";;
JSONObject json = jParser.getJSONFromURI(URI);
//protected void onPostExecute(JSONObject json) {
final String TAG_RESULTS = "ResultsSet";
final String TAG_SUBJECT = "Subject";
final String TAG_NUMANSWERS = "NumAnswers";
final String TAG_QUESTION = "Question";
final String TAG_QUESTION_CONTENT = "Content";
final String TAG_QUESTION_CHOSENANSWER = "ChosenAnswer";
final String TAG_QUESTION_ANSWERS = "Answers";
JSONArray ResultsSet = null;
ArrayList<HashMap<String, String>> questionList = new ArrayList<HashMap<String, String>>();
try {
ResultsSet = json.getJSONArray(TAG_RESULTS);
for(int i = 0; i < ResultsSet.length(); i++){
JSONObject r = ResultsSet.getJSONObject(i);
String Subject = r.getString(TAG_SUBJECT);
String NumAnswers = r.getString(TAG_NUMANSWERS);
JSONObject Question = r.getJSONObject(TAG_QUESTION);
String Content = Question.getString(TAG_QUESTION_CONTENT);
String ChosenAnswer = Question.getString(TAG_QUESTION_CHOSENANSWER);
String Answers = Question.getString(TAG_QUESTION_ANSWERS);
HashMap<String, String> map = new HashMap<String, String>();
map.put(TAG_SUBJECT, Subject);
map.put(TAG_NUMANSWERS, NumAnswers);
questionList.add(map);
}
} catch (JSONException e) {
e.printStackTrace();
}
ListAdapter adapter = new SimpleAdapter(this, questionList,
R.layout.row,
new String[] { TAG_SUBJECT, TAG_NUMANSWERS }, new int[] {
R.id.Subject, R.id.NumAnswers });
setListAdapter(adapter);
android.widget.ListView lv = getListView();
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
String Subject = view.findViewById(R.id.Subject).getContext().toString();
Intent i = new Intent(getApplicationContext(), SingleListItem.class);
i.putExtra(TAG_SUBJECT, Subject);
startActivity(i);
}
});
}
}
SingleListItem
public class SingleListItem extends Activity {
TextView subject;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setContentView(R.layout.singlelistitem);
subject = (TextView) findViewById(R.id.Subject2);
Intent i = getIntent();
String Subject = i.getStringExtra("TAG_SUBJECT");
subject.setText(Subject);
}
}