我是 android 新手，我创建了一个项目。在我的活动中，我有 ListView 和 Tabhost 以及我的活动范围 listactivity。当我运行我的项目时，它会给出错误
10-18 14:26:13.053: E/AndroidRuntime(278): FATAL EXCEPTION: main
10-18 14:26:13.053: E/AndroidRuntime(278): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.shareslab/com.example.shareslab.MessageList}: java.lang.NullPointerException
10-18 14:26:13.053: E/AndroidRuntime(278): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
10-18 14:26:13.053: E/AndroidRuntime(278): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
10-18 14:26:13.053: E/AndroidRuntime(278): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
10-18 14:26:13.053: E/AndroidRuntime(278): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
10-18 14:26:13.053: E/AndroidRuntime(278): at android.os.Handler.dispatchMessage(Handler.java:99)
10-18 14:26:13.053: E/AndroidRuntime(278): at android.os.Looper.loop(Looper.java:123)
10-18 14:26:13.053: E/AndroidRuntime(278): at android.app.ActivityThread.main(ActivityThread.java:4627)
10-18 14:26:13.053: E/AndroidRuntime(278): at java.lang.reflect.Method.invokeNative(Native Method)
10-18 14:26:13.053: E/AndroidRuntime(278): at java.lang.reflect.Method.invoke(Method.java:521)
10-18 14:26:13.053: E/AndroidRuntime(278): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
10-18 14:26:13.053: E/AndroidRuntime(278): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
10-18 14:26:13.053: E/AndroidRuntime(278): at dalvik.system.NativeStart.main(Native Method)
10-18 14:26:13.053: E/AndroidRuntime(278): Caused by: java.lang.NullPointerException
10-18 14:26:13.053: E/AndroidRuntime(278): at com.example.shareslab.MessageList.onCreate(MessageList.java:107)
10-18 14:26:13.053: E/AndroidRuntime(278): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
10-18 14:26:13.053: E/AndroidRuntime(278): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
我的活动在这里
package com.example.shareslab;
import java.util.ArrayList;
import java.util.Arrays;
import com.example.shareslab.R;
import android.app.Dialog;
import android.app.ListActivity;
import android.app.LocalActivityManager;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TabHost;
import android.widget.TabHost.TabSpec;
import android.widget.TextView;
public class MessageList extends ListActivity {
LocalActivityManager mLocalActivityManager;
public static String singleDescription;
public static String title,URLToPost,imageURL;
public static ArrayList<String> galleryImages;
private static class EfficientAdapter extends BaseAdapter
{
private LayoutInflater mInflater;
public EfficientAdapter(Context context)
{
mInflater = LayoutInflater.from(context);
}
@Override
public int getCount() {
System.out.println("description COUNT : "+SplashActivity.description.size());
return SplashActivity.description.size();
}
@Override
public Object getItem(int position) {
return position;
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent)
{
ViewHolder holder;
if (convertView == null)
{
convertView = mInflater.inflate(R.layout.inflate_list_item, null);
holder = new ViewHolder();
holder.title = (TextView) convertView.findViewById(R.id.inflate_title);
holder.des = (TextView) convertView.findViewById(R.id.inflate_description);
holder.im= (ImageView) convertView.findViewById(R.id.inflate_image);
convertView.setTag(holder);
}
else
{
holder = (ViewHolder) convertView.getTag();
}
UrlImageViewHelper.setUrlDrawable(holder.im, SplashActivity.imageURLAmit.get(position),null);
holder.title.setText(SplashActivity.titles.get(position));
holder.des.setText(SplashActivity.description.get(position));
return convertView;
}
public static class ViewHolder {
TextView title,des;
ImageView im;
}
} // close class Efficent adapter
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.main);
ListView listView = getListView();
listView.setTextFilterEnabled(true);
this.setListAdapter(new EfficientAdapter(this));
listView.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// When clicked, show a toast with the TextView text
galleryImages=new ArrayList<String>();
singleDescription=SplashActivity.description.get(position);
title=SplashActivity.titles.get(position);
URLToPost=SplashActivity.link.get(position);
imageURL=SplashActivity.imageURLAmit.get(position);
System.out.println("ON CLICK URL: "+URLToPost);
galleryImages.addAll(Arrays.asList(SplashActivity.arrays[position]));
startActivity(new Intent(MessageList.this,MessageListDetail.class));
}
});
TabHost tabHost = (TabHost)findViewById(android.R.id.tabhost);
mLocalActivityManager = new LocalActivityManager(this, false);
tabHost.setup(mLocalActivityManager);
mLocalActivityManager.dispatchCreate(icicle); //after the tab's setup is called, you have to call this or it wont work
TabHost.TabSpec spec;
Intent intent;
tabHost.getTabWidget().setDividerDrawable(R.drawable.tab_divider);
intent = new Intent().setClass(this, Home.class);
spec = tabHost.newTabSpec("tagname1").setIndicator("HOME").setContent(intent);
tabHost.addTab(spec);
intent = new Intent().setClass(this, SocialMedia.class);
spec = tabHost.newTabSpec("tagname2").setIndicator("SOCIAL MEDIA").setContent(intent);
tabHost.addTab(spec);
intent = new Intent().setClass(this, Tech.class);
spec = tabHost.newTabSpec("tagname3").setIndicator("TECH").setContent(intent);
tabHost.addTab(spec);
intent = new Intent().setClass(this, USWorld.class);
spec = tabHost.newTabSpec("tagname4").setIndicator("US & WORLD").setContent(intent);
tabHost.addTab(spec);
intent = new Intent().setClass(this, Business.class);
spec = tabHost.newTabSpec("tagname5").setIndicator("BUSINESS").setContent(intent);
tabHost.addTab(spec);
intent = new Intent().setClass(this, Fashion.class);
spec = tabHost.newTabSpec("tagname6").setIndicator("FASHION").setContent(intent);
tabHost.addTab(spec);
intent = new Intent().setClass(this, People.class);
spec = tabHost.newTabSpec("tagname7").setIndicator("PEOPLE").setContent(intent);
tabHost.addTab(spec);
intent = new Intent().setClass(this, Political.class);
spec = tabHost.newTabSpec("tagname8").setIndicator("POLITICAL").setContent(intent);
tabHost.addTab(spec);
}
@Override
protected void onPause() {
super.onPause();
mLocalActivityManager.dispatchPause(isFinishing()); //you have to manually dispatch the pause msg
}
@Override
protected void onResume() {
super.onResume();
mLocalActivityManager.dispatchResume(); //you have to manually dispatch the resume msg
}
private static View createTabView(final Context context, final String text) {
View view = LayoutInflater.from(context).inflate(R.layout.tabs_bg, null);
TextView tv = (TextView) view.findViewById(R.id.tabsText);
tv.setText(text);
return view;
}
}