Android ListView适配器空指针异常
我正在尝试实现导航抽屉,并且在listview适配器中创建空指针异常。请告诉我它为什么这样做 导航u drawer.xmlAndroid ListView适配器空指针异常,android,listview,Android,Listview,我正在尝试实现导航抽屉,并且在listview适配器中创建空指针异常。请告诉我它为什么这样做 导航u drawer.xml <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent"> <android.support.v4.widge
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<!-- The main content view -->
<FrameLayout
android:id="@+id/content_frame"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#ffffff" />
<!-- The navigation drawer -->
<ListView android:id="@+id/listview"
android:layout_width="240dp"
android:layout_height="match_parent"
android:layout_gravity="start"
android:choiceMode="singleChoice"
android:divider="@android:color/transparent"
android:dividerHeight="0dp"
android:background="#111"/>
</android.support.v4.widget.DrawerLayout>
</LinearLayout>
你能提供logcat输出吗?
还可以尝试用“父”视图实例化抽屉列表,即
ListView drawerlist=(ListView) mdrawer.findViewById(R.id.listview);
这是布局的名称->导航\u drawer.xml 这就是您设置的contentview->activity\u main.xml
我猜您缺少主布局。请显示您的日志谢谢,我尝试了此操作,但在setAdapter函数中仍然存在相同的异常。没有,我在主布局中有其他代码,甚至在导航抽屉中更改活动主布局,应用程序仍然崩溃。
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
String[] mobileArray = {"Android","IPhone","WindowsMobile","Blackberry","WebOS","Ubuntu","Windows7","Max OS X"};
DrawerLayout mdrawer=(DrawerLayout) findViewById(R.id.drawer_layout);
ArrayAdapter adapter = new ArrayAdapter<String>(this,R.layout.textdata,mobileArray);
ListView drawerlist=(ListView) findViewById(R.id.listview);
drawerlist.setAdapter(adapter);
01-01 03:46:37.180 19591-19591/com.example.shahik.myapplication E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.shahik.myapplication/com.example.shahik.myapplication.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2295)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2349)
at android.app.ActivityThread.access$700(ActivityThread.java:159)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1316)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:176)
at android.app.ActivityThread.main(ActivityThread.java:5419)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1046)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:862)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.example.shahik.myapplication.MainActivity.onCreate(MainActivity.java:44)
at android.app.Activity.performCreate(Activity.java:5372)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1104)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2257)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2349)
at android.app.ActivityThread.access$700(ActivityThread.java:159)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1316)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:176)
at android.app.ActivityThread.main(ActivityThread.java:5419)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1046)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:862)
at dalvik.system.NativeStart.main(Native Method)
ListView drawerlist=(ListView) mdrawer.findViewById(R.id.listview);