Question

我的MainActivity文件执行其他一些任务。 AccountInfo用于生成我的列表。

   public class AccountInfo extends Activity {
        TextView sublistHeadtext;
        ImageView sublistHeadImage;
        ListView listItem;
        String[] ItemViewNames;
        AccInfoCustomAdapter adapter;

        public ArrayList<String> CustomListViewValuesArr = new ArrayList<String>();

        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.sub_list);

            int value = getIntent().getExtras().getInt("listpoition");

            sublistHeadtext = (TextView) findViewById(R.id.ListItemtext);
            sublistHeadtext.setText("Account Information");

            sublistHeadImage = (ImageView) findViewById(R.id.ListItemimage);
            sublistHeadImage.setImageResource(R.drawable.accinfoimg);

            listItem = (ListView) findViewById(R.id.listItem);
            ItemViewNames = getResources().getStringArray(R.array.accInfoList);
            Log.wtf("AA", "executed !");

            /******** Take some data in Arraylist ( CustomListViewValuesArr ) ***********/
            setListData();

            /**************** Create Custom Adapter *********/
            adapter = new AccInfoCustomAdapter(CustomListViewValuesArr,
                    getBaseContext());

            //adapter = new AccInfoCustomAdapter(CustomListViewValuesArr,AccountInfo.this);
            Log.wtf("AA", "arrayList : "+CustomListViewValuesArr);
            listItem.setAdapter(adapter);
        }

        /****** Function to set data in ArrayList *************/
        public void setListData() {
            for (int i = 0; i < ItemViewNames.length; i++)
                CustomListViewValuesArr.add(ItemViewNames[i]);
        }

    }




AdatperFile

公共类AccInfoCustomAdapter扩展了BaseAdapter实现 OnClickListener {

    private ArrayList<String> list = new ArrayList<String>(); 
    private Context context; 



    public AccInfoCustomAdapter(ArrayList<String> list, Context context) { 
        this.list = list; 
        this.context = context; 
    } 

    @Override
    public int getCount() { 
        return list.size(); 
    } 

    @Override
    public Object getItem(int pos) { 
        return list.get(pos); 
    } 

    @Override
    public long getItemId(int pos) { 
       // return list.get(pos).getId();
        //just return 0 if your list items do not have an Id variable.
        return 0;
    } 

    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {
        View view = convertView;
        if (view == null) {
            LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
            view = inflater.inflate(R.layout.sublist_item, null);
        } 

        //Handle TextView and display string from your list
        TextView listItemText = (TextView)view.findViewById(R.id.ListItemtext); 
        listItemText.setText(list.get(position)); 

        //Handle buttons and add onClickListeners
        ImageButton nextBtn = (ImageButton)view.findViewById(R.id.ListItemimgbtn);


        nextBtn.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) { 

                Toast.makeText(context, "position : "+position, Toast.LENGTH_LONG).show();
            }
        });

        return view; 
    }

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub

    } 
    }

我在行

上得到一个空指针异常

listItem.setAdapter（适配器）;

我认为这里存在错误

adapter = new AccInfoCustomAdapter (CustomListViewValuesArr, getBaseContext());

LOGCAT： -

02-18 18:16:46.170: E/AndroidRuntime(16303): FATAL EXCEPTION: main
02-18 18:16:46.170: E/AndroidRuntime(16303): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.xyzbank/com.example.xyzbank.AccountInfo}: java.lang.NullPointerException
02-18 18:16:46.170: E/AndroidRuntime(16303):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2060)
02-18 18:16:46.170: E/AndroidRuntime(16303):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2085)
02-18 18:16:46.170: E/AndroidRuntime(16303):    at android.app.ActivityThread.access$600(ActivityThread.java:130)
02-18 18:16:46.170: E/AndroidRuntime(16303):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
02-18 18:16:46.170: E/AndroidRuntime(16303):    at android.os.Handler.dispatchMessage(Handler.java:99)
02-18 18:16:46.170: E/AndroidRuntime(16303):    at android.os.Looper.loop(Looper.java:137)
02-18 18:16:46.170: E/AndroidRuntime(16303):    at android.app.ActivityThread.main(ActivityThread.java:4747)
02-18 18:16:46.170: E/AndroidRuntime(16303):    at java.lang.reflect.Method.invokeNative(Native Method)
02-18 18:16:46.170: E/AndroidRuntime(16303):    at java.lang.reflect.Method.invoke(Method.java:511)
02-18 18:16:46.170: E/AndroidRuntime(16303):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
02-18 18:16:46.170: E/AndroidRuntime(16303):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
02-18 18:16:46.170: E/AndroidRuntime(16303):    at dalvik.system.NativeStart.main(Native Method)
02-18 18:16:46.170: E/AndroidRuntime(16303): Caused by: java.lang.NullPointerException
02-18 18:16:46.170: E/AndroidRuntime(16303):    at com.example.xyzbank.AccountInfo.onCreate(AccountInfo.java:45)
02-18 18:16:46.170: E/AndroidRuntime(16303):    at android.app.Activity.performCreate(Activity.java:5008)
02-18 18:16:46.170: E/AndroidRuntime(16303):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
02-18 18:16:46.170: E/AndroidRuntime(16303):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2024)
02-18 18:16:46.170: E/AndroidRuntime(16303):    ... 11 more

Answer 1

尝试将getBaseContext（）更改为“this”。

从Android中的其他活动（非主要活动）调用自定义ListView时出错？

1 个答案: