我从.net网络服务获取数据并尝试在列表视图中显示它。我编写的编码如下：
public class DisplayList extends AppCompatActivity {
private static final String TAG_CATEGORY = "main_name";
private static final String TAG_SUBCAT = "cat_name";
private static final String TAG_CODE = "code";
private static final String TAG_NAME = "name";
private static final String TAG_RATE = "rate";
private static final String TAG_RATE2 = "rate2";
private static final String TAG_RATE3 = "rate3";
private static final String TAG_IMAGE = "img";
ImageAdapter mImageAdapter = null;
ListView mListView = null;
ArrayList<DetailsVO> mListDetails = null;
String subc;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_display_list);
mListView = (ListView) findViewById(R.id.list_view);
Bundle extras = getIntent().getExtras();
if (extras != null) {
subc = extras.getString("Subcat");
}
new AsyncCallSoap1().execute();
}
public class AsyncCallSoap1 extends AsyncTask<String,Void,String> {
private final ProgressDialog dialog=new ProgressDialog(DisplayList.this);
@Override
protected String doInBackground(String... params) {
CallSoap com=new CallSoap();
String SOAP_ACTION="http://tempuri.org/IprotechService/SelectSuCatgeory";
String OPERATION_NAME="SelectSuCatgeory";
String response = com.getDetails(OPERATION_NAME,SOAP_ACTION);
if(response!=null){
try {
JSONArray array1 = new JSONArray(response);
for(int i=0;i<array1.length();i++)
{
final DetailsVO detailsVO = new DetailsVO();
JSONObject obj1 = array1.getJSONObject(i);
String out_category = obj1.getString(TAG_CATEGORY);
String out_subcat = obj1.getString(TAG_SUBCAT);
String out_code = obj1.getString(TAG_CODE);
String out_name = obj1.getString(TAG_NAME);
String out_rate = obj1.getString(TAG_RATE);
String out_rate2 = obj1.getString(TAG_RATE2);
String out_rate3 = obj1.getString(TAG_RATE3);
String out_img = obj1.getString(TAG_IMAGE);
// Toast.makeText(DetailsList.this, categoryId, Toast.LENGTH_LONG).show();
detailsVO.setName(out_name);
detailsVO.setRate(out_rate);
mListDetails.add(detailsVO);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
return response;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
//Showing progress dialog
dialog.setMessage("Please wait...");
dialog.setCancelable(false);
dialog.show();
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
dialog.dismiss();
if(mListDetails != null){
mImageAdapter = new ImageAdapter(DisplayList.this, mListDetails);
mListView.setAdapter(mImageAdapter);
}
}
}
public class ImageAdapter extends BaseAdapter {
private Context mContext;
private ArrayList<DetailsVO> mItems;
private ArrayList<DetailsVO> mOriginalItems;
public ImageAdapter(Context context, ArrayList<DetailsVO> items) {
this.mContext = context;
this.mItems = items;
}
@Override
public int getCount() {
return mItems.size();
}
@Override
public DetailsVO getItem(int position) {
return mItems.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
public ArrayList<DetailsVO> getItems(){
return mItems;
}
public View getView(int position, View convertView, ViewGroup parent) {
if (convertView == null) {
LayoutInflater mInflater = (LayoutInflater) mContext.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
convertView = mInflater.inflate(R.layout.row_layout, null);
}
DetailsVO detailsVO = mItems.get(position);
View listView = (View) convertView;
// set value into textview
TextView textTitle = (TextView) listView.findViewById(R.id.textView2);
TextView textRate = (TextView) listView.findViewById(R.id.textView3);
Button btnMap = (Button) listView.findViewById(R.id.btn_add);
btnMap.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(v.getContext(), "Feature coming soon...", Toast.LENGTH_SHORT).show();
}
});
textTitle.setText(detailsVO.getName());
textRate.setText(detailsVO.getRate());
btnMap.setTag(detailsVO);
return listView;
}
}
但我无法夸大布局。我得到的错误如下所述。请帮我解决问题
07-19 11:40:44.503 28989-29218/com.example.mayur.easygrocery E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #1
java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:299)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
at java.util.concurrent.FutureTask.run(FutureTask.java:239)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
at java.lang.Thread.run(Thread.java:856)
Caused by: java.lang.NullPointerException
at com.example.mayur.easygrocery.DisplayList$AsyncCallSoap1.doInBackground(DisplayList.java:108)
at com.example.mayur.easygrocery.DisplayList$AsyncCallSoap1.doInBackground(DisplayList.java:73)
at android.os.AsyncTask$2.call(AsyncTask.java:287)
at java.util.concurrent.FutureTask.run(FutureTask.java:234)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
at java.lang.Thread.run(Thread.java:856)
07-19 11:40:45.104 28989-28989/com.example.mayur.easygrocery E/WindowManager: Activity com.example.mayur.easygrocery.DisplayList has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{42355370 V.E..... R......D 0,0-456,144} that was originally added here
android.view.WindowLeaked: Activity com.example.mayur.easygrocery.DisplayList has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{42355370 V.E..... R......D 0,0-456,144} that was originally added here
at android.view.ViewRootImpl.<init>(ViewRootImpl.java:464)
at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:235)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:73)
at android.app.Dialog.show(Dialog.java:282)
at com.example.mayur.easygrocery.DisplayList$AsyncCallSoap1.onPreExecute(DisplayList.java:124)
at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:586)
at android.os.AsyncTask.execute(AsyncTask.java:534)
at com.example.mayur.easygrocery.DisplayList.onCreate(DisplayList.java:69)
at android.app.Activity.performCreate(Activity.java:5326)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1097)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2218)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2309)
at android.app.ActivityThread.access$700(ActivityThread.java:157)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1289)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:176)
at android.app.ActivityThread.main(ActivityThread.java:5317)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：-1)
因为mListDetails没有初始化。您可以在onPreExecute或OnCreate()
@Override
protected void onPreExecute() {
super.onPreExecute();
//Showing progress dialog
mListDetails = new Arraylist<DetailsVO>();
dialog.setMessage("Please wait...");
dialog.setCancelable(false);
dialog.show();
}