我想解析我的xml并显示他们在我的pagetitles上解析的字符串。但是我得到了nullponiterexception。
这是我的splashactivity：
package de.heron.xmlpullparser;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.List;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import de.heron.R;
import de.heron.SettingsActivity;
import de.heron.model.RoomReader;
import de.heron.parser.RoomParser;
public class SplashActivity extends FragmentActivity{
private RoomParser mNewsFeeder;
private List<RoomReader> mRssFeedList;
private static final String TOPSTORIES =
"URL";
public static String[] TabTitles = {RoomReader.getName()};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_striptabs);
mRssFeedList = new ArrayList<RoomReader>();
new DoRssFeedTask().execute(TOPSTORIES);
}
static class RssHolder {
//textview textview1; usw...
}
public class DoRssFeedTask extends AsyncTask<String, Void, List<RoomReader>> {
ProgressDialog prog;
String jsonStr = null;
Handler innerHandler;
@Override
protected void onPreExecute() {
//Context context = getContext();
prog = new ProgressDialog(SplashActivity.this);
prog.setMessage("Loading....");
prog.show();
}
@Override
protected List<RoomReader> doInBackground(String... params) {
for (String urlVal : params) {
mNewsFeeder = new RoomParser(urlVal);
}
mRssFeedList = mNewsFeeder.parse();
return mRssFeedList;
}
@Override
protected void onPostExecute(List<RoomReader> result) {
prog.dismiss();
String key = "key";
Bundle b=new Bundle();
b.putStringArray(key, new String[]{RoomReader.getName()});
Intent i=new Intent(SplashActivity.this, MainActivity.class);
i.putExtras(b);
SplashActivity.this.startActivity(i);
}
@Override
protected void onProgressUpdate(Void... values) {
}
}
}
这是我的片段适配器：
public class MyPagerAdapter extends FragmentPagerAdapter{
String key = "key";
Bundle b = MainActivity.this.getIntent().getExtras();
//public final String[] TITLES = b.getStringArray(key);
public final String[] TITLES = SplashActivity.TabTitles;
public MyPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public CharSequence getPageTitle(int position) {
return SplashActivity.TabTitles[position];//TITLES[position];
}
@Override
public Fragment getItem(int position) {
Fragment fragment = new Fragment1();
Bundle args = new Bundle();
args.putInt(Fragment1.position, position + 1);
fragment.setArguments(args);
return fragment;
}
/*@Override
public Fragment getItem(int position) {
Fragment fragment = new Fragment();
switch (position) {
case 0:
return fragment = new Fragment1();
case 1:
return fragment = new Fragment2();
default:
break;
}
return fragment;
}*/
@Override
public int getCount() {
return TITLES.length;
}
}
这是我的mainactivty中的asyntask：
private class RssAdapter extends ArrayAdapter<RoomReader> {
public RssAdapter(Context context, int textViewResourceId, List<RoomReader> rssFeedLst) {
super(context, textViewResourceId, rssFeedLst);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View view = convertView;
RssHolder rssHolder = null;
if (convertView == null) {
//textview id setzten usw..
view.setTag(rssHolder);
} else {
rssHolder = (RssHolder) view.getTag();
//textview set text RoomReader.getName() usw...
}
return view;
}
}
static class RssHolder {
//textview textview1; usw...
}
public class DoRssFeedTask extends AsyncTask<String, Void, List<RoomReader>> {
ProgressDialog prog;
String jsonStr = null;
Handler innerHandler;
@Override
protected void onPreExecute() {
//Context context = getContext();
prog = new ProgressDialog(MainActivity.this);
prog.setMessage("Loading....");
prog.show();
}
@Override
protected List<RoomReader> doInBackground(String... params) {
for (String urlVal : params) {
mNewsFeeder = new RoomParser(urlVal);
}
mRssFeedList = mNewsFeeder.parse();
return mRssFeedList;
}
@Override
protected void onPostExecute(List<RoomReader> result) {
prog.dismiss();
}
@Override
protected void onProgressUpdate(Void... values) {
}
}
来自我的主要活动的创造：
private ListView mRssListView;
private RoomParser mNewsFeeder;
private List<RoomReader> mRssFeedList;
private RssAdapter mRssAdap;
private static final String TOPSTORIES =
"the url";
private PagerSlidingTabStrip tabs;
private ViewPager pager;
private MyPagerAdapter adapter;
private static TextToSpeech tts;
private static final int REQUEST_CODE = 1234;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_striptabs);
tts = new TextToSpeech(this, this);
mRssFeedList = new ArrayList<RoomReader>();
new DoRssFeedTask().execute(TOPSTORIES);
tabs = (PagerSlidingTabStrip) findViewById(R.id.tabs);
pager = (ViewPager) findViewById(R.id.pager);
adapter = new MyPagerAdapter(getSupportFragmentManager());
pager.setAdapter(adapter);
final int pageMargin = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 4, getResources()
.getDisplayMetrics());
pager.setPageMargin(pageMargin);
tabs.setViewPager(pager);
}
日志：
08-12 18:06:00.110: E/AndroidRuntime(21128): FATAL EXCEPTION: main
08-12 18:06:00.110: E/AndroidRuntime(21128): java.lang.RuntimeException: Unable to start activity ComponentInfo{de.heron/de.heron.xmlpullparser.MainActivity}: java.lang.NullPointerException
08-12 18:06:00.110: E/AndroidRuntime(21128): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
08-12 18:06:00.110: E/AndroidRuntime(21128): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
08-12 18:06:00.110: E/AndroidRuntime(21128): at android.app.ActivityThread.access$600(ActivityThread.java:141)
08-12 18:06:00.110: E/AndroidRuntime(21128): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
08-12 18:06:00.110: E/AndroidRuntime(21128): at android.os.Handler.dispatchMessage(Handler.java:99)
08-12 18:06:00.110: E/AndroidRuntime(21128): at android.os.Looper.loop(Looper.java:137)
08-12 18:06:00.110: E/AndroidRuntime(21128): at android.app.ActivityThread.main(ActivityThread.java:5103)
08-12 18:06:00.110: E/AndroidRuntime(21128): at java.lang.reflect.Method.invokeNative(Native Method)
08-12 18:06:00.110: E/AndroidRuntime(21128): at java.lang.reflect.Method.invoke(Method.java:525)
08-12 18:06:00.110: E/AndroidRuntime(21128): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
08-12 18:06:00.110: E/AndroidRuntime(21128): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
08-12 18:06:00.110: E/AndroidRuntime(21128): at dalvik.system.NativeStart.main(Native Method)
08-12 18:06:00.110: E/AndroidRuntime(21128): Caused by: java.lang.NullPointerException
08-12 18:06:00.110: E/AndroidRuntime(21128): at com.astuetz.viewpager.extensions.PagerSlidingTabStrip.notifyDataSetChanged(PagerSlidingTabStrip.java:200)
08-12 18:06:00.110: E/AndroidRuntime(21128): at com.astuetz.viewpager.extensions.PagerSlidingTabStrip.setViewPager(PagerSlidingTabStrip.java:182)
08-12 18:06:00.110: E/AndroidRuntime(21128): at de.heron.xmlpullparser.MainActivity.onCreate(MainActivity.java:72)
08-12 18:06:00.110: E/AndroidRuntime(21128): at android.app.Activity.performCreate(Activity.java:5133)
08-12 18:06:00.110: E/AndroidRuntime(21128): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
08-12 18:06:00.110: E/AndroidRuntime(21128): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
08-12 18:06:00.110: E/AndroidRuntime(21128): ... 11 more
答案 0 :(得分：0)
我建议在打开MainActivity之前解析URL。例如，您可以创建一个Splashscreen活动并在那里编写asyncTask来解析URL，然后在splashScreen活动中的asyncTask的onPostExecute（）方法中创建一个对MainActivity的意图。您可以使用intent方法（intent.putExtra（））将解析后的字符串传递给MainActivity，或者只是设置一些静态变量。
public class SplashScreen extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.splash_screen);
new DataFromServer().execute();
}
private class DataFromServer extends AsyncTask<Void, String, Void> {
ProgressDialog progressDialog = null;
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
//super.onPreExecute();
progressDialog = ProgressDialog.show(SplashScreen.this,
"Loading...",
"Please wait while Ads are being loaded", true,
false);
}
@Override
protected Void doInBackground(Void... params) {
/* fetch the data from server here and set the titles variables of the
MainActivity */
// e.g
MainActivity.tab1_title = some_data_from_server;
MainActivity.tab2_title = some_data_from_server;
MainActivity.tab3_title = some_data_from_server;
return null;
}
@Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
//super.onPostExecute(result);
Log.e("tab1: ",MainActivity.tab1_title);
Log.e("tab2: ",MainActivity.tab2_title);
Log.e("tab3: ",MainActivity.tab3_title);
Intent intent = new Intent(SplashScreen.this,MainActivity.Class);
StartActivity(intent);
SplashScreen.this.finish();
if (progressDialog != null) {
progressDialog.dismiss();
}
}
}
}
public class MainActivity extends Activity {
public static String tab1_title;
public static String tab2_title;
public static String tab3_title;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Now you can use the tab1_title, tab2_title and tab3_title here
}
}