0

此代码有效

public class listActivity extends ListActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);

    testAdapter mDbHelper = new testAdapter(this);

    mDbHelper.open();
    Cursor c = mDbHelper.getAllData();

    String[] from = new String[] { "name", "title" };

    CursorAdapter dataSource = new SimpleCursorAdapter(this,
            R.layout.list_row, c, from, new int[] { R.id.name,
                    R.id.title});

    setListAdapter(dataSource);

    mDbHelper.close();
}

但是当我尝试在我的一个布局中将适配器设置为列表视图时，它只会崩溃

public class listActivity extends ListActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);

    testAdapter mDbHelper = new testAdapter(this);

    mDbHelper.open();
    Cursor c = mDbHelper.getAllData();

    String[] from = new String[] { "name", "title" };

    CursorAdapter dataSource = new SimpleCursorAdapter(this,
            R.layout.list_row, c, from, new int[] { R.id.name,
                    R.id.title});

    ListView itemList = (ListView)findViewById(R.id.itemsList);
    itemList.setAdapter(dataSource);   // line 29 where it crashes

    mDbHelper.close();
}

这就是 LogCat 抛出的

04-13 20:58:09.331: E/DataAdapter(929): opened db
04-13 20:58:09.451: D/AndroidRuntime(929): Shutting down VM
04-13 20:58:09.451: W/dalvikvm(929): threadid=1: thread exiting with uncaught exception (group=0x40015560)
04-13 20:58:09.521: E/AndroidRuntime(929): FATAL EXCEPTION: main
04-13 20:58:09.521: E/AndroidRuntime(929): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.app/com.example.app.listActivity}: java.lang.NullPointerException
04-13 20:58:09.521: E/AndroidRuntime(929):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
04-13 20:58:09.521: E/AndroidRuntime(929):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
04-13 20:58:09.521: E/AndroidRuntime(929):  at android.app.ActivityThread.access$1500(ActivityThread.java:117)
04-13 20:58:09.521: E/AndroidRuntime(929):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
04-13 20:58:09.521: E/AndroidRuntime(929):  at android.os.Handler.dispatchMessage(Handler.java:99)
04-13 20:58:09.521: E/AndroidRuntime(929):  at android.os.Looper.loop(Looper.java:123)
04-13 20:58:09.521: E/AndroidRuntime(929):  at android.app.ActivityThread.main(ActivityThread.java:3683)
04-13 20:58:09.521: E/AndroidRuntime(929):  at java.lang.reflect.Method.invokeNative(Native Method)
04-13 20:58:09.521: E/AndroidRuntime(929):  at java.lang.reflect.Method.invoke(Method.java:507)
04-13 20:58:09.521: E/AndroidRuntime(929):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
04-13 20:58:09.521: E/AndroidRuntime(929):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
04-13 20:58:09.521: E/AndroidRuntime(929):  at dalvik.system.NativeStart.main(Native Method)
04-13 20:58:09.521: E/AndroidRuntime(929): Caused by: java.lang.NullPointerException
04-13 20:58:09.521: E/AndroidRuntime(929):  at com.exmaple.app.listActivity.onCreate(listActivity.java:29)
04-13 20:58:09.521: E/AndroidRuntime(929):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
04-13 20:58:09.521: E/AndroidRuntime(929):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
04-13 20:58:09.521: E/AndroidRuntime(929):  ... 11 more

我已经为此苦苦挣扎了好几个星期，所以请任何帮助将不胜感激。

4

1 回答 1

0

你还没有调用setContentView()，代码找不到你的R.id.itemsList视图。itemsList一片空白。

于 2013-04-13T21:19:07.417 回答