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使用本教程：http ://www.lucazanini.eu/2012/android/swipe-views/?lang= en，我现在可以基于几个 xml 文件创建滑动页面。

假设第一页是 tab1.xml，它包含：

<Button
    android:id="@+id/myButton"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="this is my button"
    android:onClick="myButton_onClick" />

第二页是tab2.xml，它有：

<ImageView
    android:id="@+id/myImageView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_weight="1"
    android:scaleType="fitXY"
    android:src="@drawable/something" />

现在我的应用程序可以从一个页面滑动到另一个页面，这正是我想要的。但是，当我尝试控制 MainActivity.java 上的<Button>and<ImageView>时，它总是给我 nullpointerexception 错误。

然后我意识到这两者<Button>都不<ImageView>是activity_main.xml的一部分，所以它可能无法从MainActivity.java访问。实际上activity_main.xml 只包含每个可滑动页面的标题。现在我什至不知道将按钮的 onClick 事件放在哪里。

我希望一些android专家能给我一个线索。

日志：

11-05-21:48:50.061: D/ActivityThread(13482): setTargetHeapUtilization:0.25
11-05-21:48:50.061: D/ActivityThread(13482): setTargetHeapIdealFree:8388608
11-05-21:48:50.061: D/ActivityThread(13482): setTargetHeapConcurrentStart:2097152
11-05-21:48:50.251: W/dalvikvm(13482): threadid=1: thread exiting with uncaught exception (group=0x40c5e498)
11-05-21:48:50.251: E/AndroidRuntime(13482): FATAL EXCEPTION: main
11-05-21:48:50.251: E/AndroidRuntime(13482): java.lang.NullPointerException
11-05-21:48:50.251: E/AndroidRuntime(13482):    at com.anggrian.speaknow.MainActivity$TabFragment.onCreateView(MainActivity.java:152)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.support.v4.app.Fragment.performCreateView(Fragment.java:1500)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:927)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1467)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:472)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.support.v4.view.ViewPager.populate(ViewPager.java:1068)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.support.v4.view.ViewPager.populate(ViewPager.java:914)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1436)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.view.View.measure(View.java:15247)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4834)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.view.View.measure(View.java:15247)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.widget.LinearLayout.measureVertical(LinearLayout.java:833)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.view.View.measure(View.java:15247)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4834)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2148)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.view.View.measure(View.java:15247)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1881)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1129)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1306)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1027)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4359)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.view.Choreographer.doCallbacks(Choreographer.java:555)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.view.Choreographer.doFrame(Choreographer.java:525)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.os.Handler.handleCallback(Handler.java:615)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.os.Handler.dispatchMessage(Handler.java:92)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.os.Looper.loop(Looper.java:137)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at android.app.ActivityThread.main(ActivityThread.java:4812)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at java.lang.reflect.Method.invokeNative(Native Method)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at java.lang.reflect.Method.invoke(Method.java:511)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
11-05-21:48:50.251: E/AndroidRuntime(13482):    at dalvik.system.NativeStart.main(Native Method)
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1 回答 1

1

您需要从包含它们的片段中访问这些视图。在 Fragment 的onCreateView方法中获取对这些元素的引用，并在其中处理任何操作，或者onActivityCreated如果您想安全起见，也可以在其中处理任何操作。

在您提供的示例中，您将执行以下操作：

public static class TabFragment extends Fragment {

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
     Bundle savedInstanceState) {
     View rootView = inflater.inflate(tabLayout, container, false);
     ImageView img = (Button) rootView.findViewById(R.id.img);
     img.setImageResource(R.drawable.img_drawable);
     // Get a reference to your button and add onClick listener here as well
     return rootView;
}

}
于 2013-11-05T14:00:31.450 回答