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I having a crucial problem on deploying a custom arrayadapter on android connected google app engine project. Even though there are no errors while typing the code when I debug the application as an Android app with the emulator causes an error and the application stops. My custom adapter code is below and according the debugger there is NullPointerException after line 46. What is this and how to fix it? 

package com.cheapchase;

import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;

public class MyListAdapter extends ArrayAdapter<ListItem>{

    Context context;
    int layoutResourceId;
    ListItem data[] = null;

    public MyListAdapter(Context context, int layoutResourceId, ListItem[] data){

        super(context,layoutResourceId, data);
        this.layoutResourceId = layoutResourceId;
        this.context = context;
        this.data = data;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent){

        View row = convertView;
        ListHolder holder = null;

        if(row == null){

            LayoutInflater inflater = ((Activity)context).getLayoutInflater();
            row = inflater.inflate(layoutResourceId, parent, false);

            holder = new ListHolder();
            holder.imgIcon = (ImageView)row.findViewById(R.id.imgIcon);
            holder.txtTitle = (TextView)row.findViewById(R.id.txtTitle);
        }
        else
        {
            holder = (ListHolder)row.getTag();
        }

        ListItem listrow = data[position];
        holder.txtTitle.setText(listrow.title);
        holder.imgIcon.setImageResource(listrow.icon);

        return row;
    }

    static class ListHolder
    {
        ImageView imgIcon;
        TextView txtTitle;
    }

}

This is the activity calling the adapter:

import android.app.Activity;
import android.os.Bundle;
import android.widget.ListView;

public class StoresList extends Activity{

    /**
     * The current context.
     */

    private ListView listView1;

    @Override
    public void onCreate(Bundle savedInstanceState){

        super.onCreate(savedInstanceState);
        setContentView(R.layout.store_list);
    }

    public void onResume(){

        super.onResume();

        ListItem storelist[] = new ListItem[]{
                new ListItem(R.drawable.androidmsg, "test1"),
                new ListItem(R.drawable.androidmsg, "test2")
        };


        MyListAdapter adapter = new MyListAdapter(this, R.layout.listview_item_row, storelist);

        listView1 = (ListView)findViewById(R.id.listView1);

        /*View header = (View)getLayoutInflater().inflate(R.layout.listview_item_header, null);
        listView1.addHeaderView(header);*/

        listView1.setAdapter(adapter);
    }



// **** end of file 
}

This is the error log...

06-28 15:16:44.687: W/dalvikvm(1584): threadid=1: thread exiting with uncaught exception (group=0x40015560)
06-28 15:16:44.706: E/AndroidRuntime(1584): FATAL EXCEPTION: main
06-28 15:16:44.706: E/AndroidRuntime(1584): java.lang.RuntimeException: Unable to resume activity {com.cheapchase/com.cheapchase.StoresList}: android.app.SuperNotCalledException: Activity {com.cheapchase/com.cheapchase.StoresList} did not call through to super.onResume()
06-28 15:16:44.706: E/AndroidRuntime(1584):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2120)
06-28 15:16:44.706: E/AndroidRuntime(1584):     at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2135)
06-28 15:16:44.706: E/AndroidRuntime(1584):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1668)
06-28 15:16:44.706: E/AndroidRuntime(1584):     at android.app.ActivityThread.access$1500(ActivityThread.java:117)
06-28 15:16:44.706: E/AndroidRuntime(1584):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
06-28 15:16:44.706: E/AndroidRuntime(1584):     at android.os.Handler.dispatchMessage(Handler.java:99)
06-28 15:16:44.706: E/AndroidRuntime(1584):     at android.os.Looper.loop(Looper.java:130)
06-28 15:16:44.706: E/AndroidRuntime(1584):     at android.app.ActivityThread.main(ActivityThread.java:3683)
06-28 15:16:44.706: E/AndroidRuntime(1584):     at java.lang.reflect.Method.invokeNative(Native Method)
06-28 15:16:44.706: E/AndroidRuntime(1584):     at java.lang.reflect.Method.invoke(Method.java:507)
06-28 15:16:44.706: E/AndroidRuntime(1584):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
06-28 15:16:44.706: E/AndroidRuntime(1584):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
06-28 15:16:44.706: E/AndroidRuntime(1584):     at dalvik.system.NativeStart.main(Native Method)
06-28 15:16:44.706: E/AndroidRuntime(1584): Caused by: android.app.SuperNotCalledException: Activity {com.cheapchase/com.cheapchase.StoresList} did not call through to super.onResume()
06-28 15:16:44.706: E/AndroidRuntime(1584):     at android.app.Activity.performResume(Activity.java:3834)
06-28 15:16:44.706: E/AndroidRuntime(1584):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2110)
06-28 15:16:44.706: E/AndroidRuntime(1584):     ... 12 more
06-28 15:17:19.967: W/ActivityThread(1617): Application com.cheapchase is waiting for the debugger on port 8100...

Thank you for your help.

4

1 回答 1

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你从来没有设置标签值，所以当你这样做时，holder = (ListHolder)row.getTag();它会返回null.

        holder = new ListHolder();
        holder.imgIcon = (ImageView)row.findViewById(R.id.imgIcon);
        holder.txtTitle = (TextView)row.findViewById(R.id.txtTitle);
        row.setTag(holder);  //<--- missing this

编辑：除了现在你的日志抱怨 SuperNotCalled。

于 2012-06-28T15:50:23.007 回答