我有以下JSON文件：
[
{
"Date" : "11182013",
"Quote" : "Today Is Monday",
"By" : "SiKni8"
},
{
"Date" : "11192013",
"Quote" : "Today Is Tuesday",
"By" : "SiKni8"
}
]
我的Java代码可以在这里找到： http://pastebin.com/9Wta9GYh
代码：
package com.test.testing;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Calendar;
import java.util.Locale;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.BasicHttpParams;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.PendingIntent;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.Context;
import android.content.Intent;
import android.os.AsyncTask;
import android.util.Log;
import android.widget.RemoteViews;
import android.widget.Toast;
public class DisplayHadith extends AppWidgetProvider {
public static String CLOCK_WIDGET_UPDATE = "CLOCK_WIDGET_UPDATE";
Calendar c = Calendar.getInstance();
DateFormat df = new SimpleDateFormat("LLDyyyy", Locale.US);
DefaultHttpClient httpclient;
HttpPost httppost;
InputStream inputStream = null;
String result = null;
StringBuilder sb;
JSONArray jsonArray;
String[] date, quote, by;
RemoteViews views;
@Override
public void onReceive(Context context, Intent intent) {
super.onReceive(context, intent);
if (CLOCK_WIDGET_UPDATE.equals(intent.getAction())) {
Toast.makeText(context, "onReceiver()", Toast.LENGTH_LONG).show();
}
new GetJSON().execute(null, null, null);
}
public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
final int N = appWidgetIds.length;
Log.i("ExampleWidget", "Updating widgets " + Arrays.asList(appWidgetIds));
// Perform this loop procedure for each App Widget that belongs to this
// provider
for (int i = 0; i < N; i++) {
int appWidgetId = appWidgetIds[i];
// Create an Intent to launch MainActivity
Intent intent = new Intent(context, MainActivity.class);
PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, intent, 0);
// Get the layout for the App Widget and attach an on-click listener
// to the button
views = new RemoteViews(context.getPackageName(),
R.layout.widgetlayout);
views.setOnClickPendingIntent(R.id.ivCal, pendingIntent);
views.setOnClickPendingIntent(R.id.tvParkStatus, pendingIntent);
views.setOnClickPendingIntent(R.id.tvToday, pendingIntent);
views.setTextViewText(R.id.tvParkStatus, "Alternate Parking is Suspended");
// Tell the AppWidgetManager to perform an update on the current app
// widget
appWidgetManager.updateAppWidget(appWidgetId, views);
}
}
public static void updateAppWidget(Context context, AppWidgetManager appWidgetManager, int appWidgetId) {
RemoteViews updateViews = new RemoteViews(context.getPackageName(), R.layout.widgetlayout);
appWidgetManager.updateAppWidget(appWidgetId, updateViews);
}
public class GetJSON extends AsyncTask<Void, Void, Void> {
@Override
protected Void doInBackground(Void... params) { //Running in background
try {
httpclient = new DefaultHttpClient(new BasicHttpParams());
HttpPost httppost = new HttpPost("http://pagesbyz.com/hadith.json");
// Depends on your web service
httppost.setHeader("Content-type", "application/json");
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
inputStream = entity.getContent();
// json is UTF-8 by default
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"), 8);
sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null)
{
sb.append(line + "\n");
}
result = sb.toString();
} catch (Exception e) {
Log.i("TEST", e.toString());
// Oops
}
finally {
try{if(inputStream != null)inputStream.close();}catch(Exception squish){}
}
return null;
}
@Override
protected void onPreExecute() { //Activity is on progress
}
@Override
protected void onPostExecute(Void v) {
try {
jsonArray = new JSONArray(result);
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject jsonObj = (JSONObject) jsonArray.get(i);
date[i] = jsonObj.getString("Date");
quote[i] = jsonObj.getString("Quote");
by[i] = jsonObj.getString("By");
} // End the for loop
views.setTextViewText(R.id.tvToday, date[0]);
}
catch (JSONException e) {
e.printStackTrace();
}
}
}
}
我正在尝试在窗口小部件TextView中显示日期，但我收到的是带有以下LogCat的FC：
11-19 16:18:15.226: E/AndroidRuntime(1562): FATAL EXCEPTION: main
11-19 16:18:15.226: E/AndroidRuntime(1562): java.lang.NullPointerException
11-19 16:18:15.226: E/AndroidRuntime(1562): at com.test.dailyhadith.testing$GetJSON.onPostExecute(testing.java:134)
11-19 16:18:15.226: E/AndroidRuntime(1562): at com.test.dailyhadith.testing$GetJSON.onPostExecute(testing.java:1)
11-19 16:18:15.226: E/AndroidRuntime(1562): at android.os.AsyncTask.finish(AsyncTask.java:631)
11-19 16:18:15.226: E/AndroidRuntime(1562): at android.os.AsyncTask.access$600(AsyncTask.java:177)
11-19 16:18:15.226: E/AndroidRuntime(1562): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
11-19 16:18:15.226: E/AndroidRuntime(1562): at android.os.Handler.dispatchMessage(Handler.java:99)
11-19 16:18:15.226: E/AndroidRuntime(1562): at android.os.Looper.loop(Looper.java:137)
11-19 16:18:15.226: E/AndroidRuntime(1562): at android.app.ActivityThread.main(ActivityThread.java:4745)
11-19 16:18:15.226: E/AndroidRuntime(1562): at java.lang.reflect.Method.invokeNative(Native Method)
11-19 16:18:15.226: E/AndroidRuntime(1562): at java.lang.reflect.Method.invoke(Method.java:511)
11-19 16:18:15.226: E/AndroidRuntime(1562): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
11-19 16:18:15.226: E/AndroidRuntime(1562): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
11-19 16:18:15.226: E/AndroidRuntime(1562): at dalvik.system.NativeStart.main(Native Method)
我该如何解决？
答案 0 :(得分：1)
这与JSON无关。您永远不会初始化String [] date数组。
你需要的东西......
date = new String[jsonArray.length()];