Question

我正在获取我的联系人姓名并将其添加到ArrayList。

方法displayContacts（）正在运行，因为我的结果显示在我的logcat权限中。在onCreate()中，当我得到ArrayList的大小时，结果也是正确的。

我正在延长ListActivity并使用ArrayAdapter<String>

代码是：

public class MainActivity extends ListActivity  {


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


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    displayContacts();


    Log.i("tag", "ARRAYLIST SIZE== " + names.size() );


    //ListView listView = (ListView) findViewById(R.id.list);
    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, 
            android.R.layout.simple_list_item_1, names);

    setListAdapter(adapter);        

}



private void displayContacts() {

    ContentResolver cr = getContentResolver();
    Cursor cur = cr.query(ContactsContract.Contacts.CONTENT_URI,
            null, null, null, null);

    if (cur.getCount() > 0) {
        while (cur.moveToNext()) {

            String name = cur.getString(cur.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME));
            names.add(name);

            //Log.i("name", "name= " + name );

        }
        Log.i("tag", "Close Cursor");
        cur.close();
    }

}   



}

XML布局文件：

<?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
         android:orientation="vertical"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:paddingLeft="8dp"
         android:paddingRight="8dp">


    <ListView android:id="@android:id/list"
               android:layout_width="match_parent"
               android:layout_height="wrap_content"  />


</LinearLayout>

logcat中的错误：

01-22 20:55:28.280: E/AndroidRuntime(2597): FATAL EXCEPTION: main
01-22 20:55:28.280: E/AndroidRuntime(2597): java.lang.NullPointerException
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.widget.ArrayAdapter.getView(ArrayAdapter.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.widget.AbsListView.obtainView(AbsListView.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.widget.ListView.measureHeightOfChildren(ListView.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.widget.ListView.onMeasure(ListView.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.view.View.measure(View.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.widget.LinearLayout.measureVertical(LinearLayout.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.widget.LinearLayout.onMeasure(LinearLayout.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.view.View.measure(View.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.widget.FrameLayout.onMeasure(FrameLayout.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.view.View.measure(View.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.widget.LinearLayout.measureVertical(LinearLayout.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.widget.LinearLayout.onMeasure(LinearLayout.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.view.View.measure(View.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.widget.FrameLayout.onMeasure(FrameLayout.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.view.View.measure(View.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.view.Choreographer$CallbackRecord.run(Choreographer.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.view.Choreographer.doCallbacks(Choreographer.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.view.Choreographer.doFrame(Choreographer.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.os.Handler.handleCallback(Handler.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.os.Handler.dispatchMessage(Handler.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.os.Looper.loop(Looper.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at android.app.ActivityThread.main(ActivityThread.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at java.lang.reflect.Method.invokeNative(Native Method)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at java.lang.reflect.Method.invoke(Method.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java)
01-22 20:55:28.280: E/AndroidRuntime(2597):     at dalvik.system.NativeStart.main(Native Method)

我应该创建自定义ArrayAdapter吗？但是只要我能将数据添加到字符串的ArrayList中，它对我没有任何意义。

Answer 1

做两件事之一：

不要在onCreate（）中调用setContentView（）
将TextView添加到xml中。然后传递TextView的id而不是android.R.layout.simple_list_item_1。

将ArrayList <string>填充到ListView </string>时的NPE

1 个答案: