我正在尝试解析json数据，添加arraylist并将其传递给listview。但是当我尝试使用android AsyncTask Arraylist.add函数中的doInBackground将项添加到列表时，它无效。当我尝试从列表中读取数据时，我的屏幕崩溃了。
public class QueueManagement extends Activity {
String queueUrl = "http://dev.woofyz.com/api/pet/queue";
ListView list;
ArrayList<String> petImage = new ArrayList<String>();
ArrayList<String> petName = new ArrayList<String>();
ArrayList<String> petSpecie = new ArrayList<String>();
ArrayList<String> petBreed = new ArrayList<String>();
ArrayList<String> petAge = new ArrayList<String>();
ArrayList<String> petOwner = new ArrayList<String>();
ArrayList<String> petToken = new ArrayList<String>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.queue_layout);
//TOP MENU
CustomActionBar customAactionBar = new CustomActionBar(QueueManagement.this);
ActionBar actionBar = customAactionBar.getActionBar();
actionBar.setCustomView(R.layout.custom_queue_menu);
//SETTING VALUE IN NAV SPINNER
MenuSpinner mspinner = new MenuSpinner(QueueManagement.this);
ArrayAdapter dataAdapter = mspinner.getQueueSpinner();
Spinner spinner = (Spinner) findViewById(R.id.righttext);
spinner.setAdapter(dataAdapter);
//MAKE DOCTOR PROFILE CIRCULAR
ImageView imageView = (ImageView) findViewById(R.id.doctorProfilepic);
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.doctor);
RoundImage roundImage = new RoundImage();
Bitmap circle = roundImage.getRoundImage(bitmap);
imageView.setImageBitmap(circle);
}
@Override
protected void onResume() {
super.onResume();
new AsyncCaller().execute();
}
private class AsyncCaller extends AsyncTask<Void, Void, Void> {
ProgressDialog pdLoading = new ProgressDialog(QueueManagement.this);
@Override
protected void onPreExecute() {
super.onPreExecute();
pdLoading.setMessage("\tLoading...");
pdLoading.show();
}
@Override
protected Void doInBackground(Void... params) {
JsonParser jParser = new JsonParser();
JSONArray json = jParser.getJsonFromUrl(queueUrl);
for (int i = 0; i < json.length(); i++) {
try {
JSONObject jo = json.getJSONObject(i);
//petImage.add(jo.getString("image"));
petName.add(jo.getString("name"));
//petSpecie.add(jo.getString("species"));
//petBreed.add(jo.getString("breed"));
//petAge.add(jo.getString("age"));
//petOwner.add(jo.getString("owner"));
//petToken.add(jo.getString("token"));
}catch (JSONException e) {
e.printStackTrace();
}
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
pdLoading.dismiss();
CustomQueueListview adapter = new CustomQueueListview(QueueManagement.this,petImage,petName,petSpecie,petBreed,petAge,petOwner,petToken);
list=(ListView)findViewById(R.id.queuelist);
list.setAdapter(adapter);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// INFLATE THE MENU
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.queue_menu, menu);
return true;
}
@Override
public void onStart() {
super.onStart();
TextView name = (TextView) findViewById(R.id.doctorname);
name.setText(petName.get(0));
//FILTER ClICK
ImageView filter = (ImageView) findViewById(R.id.filter);
filter.setOnClickListener(new View.OnClickListener() {
public void onClick(View myView){
CustomPopup popup = new CustomPopup(QueueManagement.this);
popup.getFilterPopup();
}
});
//SENDNEXT ClICK
Button sendNext = (Button) findViewById(R.id.sendnext);
sendNext.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View myView){
Intent intent = new Intent(QueueManagement.this, PetProfile.class);
startActivity(intent);
}
});
}
}
这是我的json解析器代码
public class JsonParser {
static InputStream is = null;
static JSONArray jarray = null;
static String json = "";
public JsonParser() {
}
public JSONArray getJsonFromUrl(String url) {
try {
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpGet httpPost = new HttpGet(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
} catch (Exception e) {
e.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line);
}
is.close();
json = sb.toString();
} catch (Exception e) {
e.printStackTrace();
}
// try parse the string to a JSON ARRAY
try {
jarray = new JSONArray(json);
} catch (Exception e) {
e.printStackTrace();
}
// return JSON ARRAY
return jarray;
}
}
这是我的logcat
E/AndroidRuntime(13507): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2198)
E/AndroidRuntime(13507): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2257)
E/AndroidRuntime(13507): at android.app.ActivityThread.access$800(ActivityThread.java:139)
E/AndroidRuntime(13507): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210)
E/AndroidRuntime(13507): at android.os.Handler.dispatchMessage(Handler.java:102)
E/AndroidRuntime(13507): at android.os.Looper.loop(Looper.java:136)
E/AndroidRuntime(13507): at android.app.ActivityThread.main(ActivityThread.java:5086)
E/AndroidRuntime(13507): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(13507): at java.lang.reflect.Method.invoke(Method.java:515)
E/AndroidRuntime(13507): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
E/AndroidRuntime(13507): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
E/AndroidRuntime(13507): at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime(13507): Caused by: java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
E/AndroidRuntime(13507): at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255)
E/AndroidRuntime(13507): at java.util.ArrayList.get(ArrayList.java:308)
E/AndroidRuntime(13507): at org.woofyz.QueueManagement.onStart(QueueManagement.java:145)
E/AndroidRuntime(13507): at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1194)
E/AndroidRuntime(13507): at android.app.Activity.performStart(Activity.java:5258)
E/AndroidRuntime(13507): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2171)
E/AndroidRuntime(13507): ... 11 more
E/cutils ( 245): Failed to mkdirat(/storage/sdcard1/Android): Read-only file system
E/chromium(16926): [ERROR:simple_index_file.cc(223)] Failed to write the temporary index file
E/chromium(16926): [ERROR:simple_index_file.cc(223)] Failed to write the temporary index file
E/chromium_android_linker(13558): Open: Could not open libchrome.so: Could not map at 0x54b7f000 requested, backing out
E/chromium_android_linker(13558): Unable to load library: libchrome.so
E/libEGL (13558): validate_display:254 error 3008 (EGL_BAD_DISPLAY)
E/libEGL (13558): validate_display:254 error 3008 (EGL_BAD_DISPLAY)
E/OMXMaster(13558): A component of name 'OMX.qcom.audio.decoder.aac' already exists, ignoring this one.
E/cutils ( 245): Failed to mkdirat(/storage/sdcard1/Android): Read-only file system
E/NetworkScheduler.SchedulerReceiver( 1351): Invalid parameter app
E/NetworkScheduler.SchedulerReceiver( 1351): Invalid package name : Perhaps you didn't include a PendingIntent in the extras?
E/AuthorizationBluetoothService( 1351): Proximity feature is not enabled.
E/AuthorizationBluetoothService( 1351): Proximity feature is not enabled.
E/dalvikvm(13849): Could not find class 'android.telecom.TelecomManager', referenced from method com.google.android.gms.wearable.service.y.a
E/MDM ( 1237): [79] b.run: Couldn't connect to Google API client: ConnectionResult{statusCode=API_UNAVAILABLE, resolution=null}
E/MDM ( 1237): [79] b.run: Couldn't connect to Google API client: ConnectionResult{statusCode=API_UNAVAILABLE, resolution=null}
E/ActivityThread(13818): Failed to find provider info for com.facebook.katana.provider.AttributionIdProvider
E/ActivityThread(13818): Failed to find provider info for com.facebook.katana.provider.AttributionIdProvider
E/dalvikvm(13898): Could not find class 'android.app.Notification$Action$Builder', referenced from method g.a
E/dalvikvm(13898): Could not find class 'android.app.RemoteInput$Builder', referenced from method g.a
E/dalvikvm(13898): Could not find class 'android.app.Notification$Action$Builder', referenced from method g.a
E/dalvikvm(13898): Could not find class 'android.text.style.TtsSpan', referenced from method g.a
E/dalvikvm(13898): Could not find class 'ax', referenced from method g.a
E/dalvikvm(13898): Could not find class 'az', referenced from method g.a
E/dalvikvm(13898): Could not find class 'android.app.RemoteInput[]', referenced from method g.a
E/dalvikvm(13898): Could not find class 'com.google.android.apps.hangouts.telephony.TeleConnectionService', referenced from method g.l
E/dalvikvm(13898): Could not find class 'android.telecom.TelecomManager', referenced from method g.n
E/SQLiteLog(13898): (1) no such table: mmsconfig
E/Babel_SMS(13898): canonicalizeMccMnc: invalid mccmnc nullnull
E/dalvikvm(13898): Could not find class 'fzc', referenced from method com.google.android.libraries.hangouts.video.sdk.ScreenVideoCapturer.<init>
E/dalvikvm(13898): Could not find class 'android.telecom.PhoneAccount$Builder', referenced from method dry.f
E/dalvikvm(13898): Could not find class 'android.telecom.TelecomManager', referenced from method dry.i
E/chromium(16926): [ERROR:simple_index_file.cc(223)] Failed to write the temporary index file
E/chromium(16926): [ERROR:simple_index_file.cc(223)] Failed to write the temporary index file
E/libEGL (13974): validate_display:254 error 3008 (EGL_BAD_DISPLAY)
E/libEGL (13974): validate_display:254 error 3008 (EGL_BAD_DISPLAY)
E/OMXMaster(13974): A component of name 'OMX.qcom.audio.decoder.aac' already exists, ignoring this one.
E/MDMCTBK ( 583): MdmCutbackHndler,Could not open ''
E/MDMCTBK ( 583): MdmCutbackHndler,Could not open ''
E/audio_a2dp_hw( 260): adev_set_parameters: ERROR: set param called even when stream out is null
E/chromium(16926): [ERROR:simple_index_file.cc(223)] Failed to write the temporary index file
E/chromium(16926): [ERROR:get_updates_processor.cc(243)] PostClientToServerMessage() failed during GetUpdates
E/pIntent (18302): started scanning called
E/MDMCTBK ( 583): MdmCutbackHndler,Could not open ''
E/MDMCTBK ( 583): MdmCutbackHndler,Could not open ''
E/WakeLock(13053): callingPackage is not supposed to be empty for wakelock Config Service fetch!
E/pIntent (18302): started scanning called
答案 0 :(得分：0)
为了解析JSON对象，我们将创建一个类JSONObject的对象，并指定一个包含JSON数据的字符串。它的语法是：
String in;
JSONObject reader = new JSONObject(in);
最后一步是解析JSON。 JSON文件由具有不同键/值对e.t.c的不同对象组成。所以JSONObject有一个单独的函数来解析JSON文件的每个组件。其语法如下：
JSONObject sys = reader.getJSONObject("sys");
country = sys.getString("country");
JSONObject main = reader.getJSONObject("main");
temperature = main.getString("temp");
方法getJSONObject返回JSON对象。方法getString返回指定键的字符串值。
对于教程，你可以see这个