soory我是新手，我希望通过以下教程在我的应用程序中使用tabs功能构建滑动视图：
http://www.androidhive.info/2013/10/android-tab-layout-with-swipeable-views-1/
并且我成功了，但是当我尝试在我的第一个默认选项卡视图片段中使用登录sessionmanager和sqlitehandler时，名为“TopRatedFragmentActivity”。我的应用程序强制关闭......“不幸的是已停止”。这是我的代码：
public class TopRatedFragment extends Fragment {
private TextView txtName;
private TextView txtEmail;
private Button btnLogout;
private SQLiteHandler db;
private SessionManager session;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_top_rated, container, false);
txtName = (TextView) getView().findViewById(R.id.name);
txtEmail = (TextView) getView().findViewById(R.id.email);
btnLogout = (Button) getView().findViewById(R.id.btnLogout);
// SqLite database handler
db = new SQLiteHandler(getActivity());
// session manager
session = new SessionManager(getActivity());
if (!session.isLoggedIn()) {
logoutUser();
}
// Fetching user details from sqlite
HashMap<String, String> user = db.getUserDetails();
String name = user.get("name");
String email = user.get("email");
// Displaying the user details on the screen
txtName.setText(name);
txtEmail.setText(email);
// Logout button click event
btnLogout.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
logoutUser();
}
});
return rootView;
}
/**
* Logging out the user. Will set isLoggedIn flag to false in shared
* preferences Clears the user data from sqlite users table
* */
private void logoutUser() {
session.setLogin(false);
db.deleteUsers();
// Launching the login activity
Intent intent = new Intent(getActivity(), LoginActivity.class);
startActivity(intent);
}
这是我的fragment_top_rated.xml代码：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="#fa6a6a" >
<LinearLayout
android:orientation="vertical"
android:layout_gravity="bottom"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TabWidget
android:id="@android:id/tabs"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
<FrameLayout
android:id="@android:id/tabcontent"
android:layout_width="fill_parent"
android:layout_height="fill_parent"/>
</LinearLayout>
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:layout_marginLeft="20dp"
android:layout_marginRight="20dp"
android:gravity="center"
android:orientation="vertical" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/welcome"
android:textSize="20dp" />
<TextView
android:id="@+id/name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="10dp"
android:textColor="@color/lbl_name"
android:textSize="24dp" />
<TextView
android:id="@+id/email"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="13dp" />
<Button
android:id="@+id/btnLogout"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginTop="40dip"
android:background="@color/btn_logut_bg"
android:text="@string/btn_logout"
android:textAllCaps="false"
android:textColor="@color/white"
android:textSize="15dp" />
</LinearLayout>
</RelativeLayout>
这里，错误logcat：
08-13 21:55:08.204 6243-6243/id.nijushop.app.ikutan W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0xa6282288)
08-13 21:55:08.208 6243-6243/id.nijushop.app.ikutan E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.NullPointerException
at id.nijushop.app.ikutan.TopRatedFragment.onCreateView(TopRatedFragment.java:32)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1789)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:955)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1138)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:740)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1501)
at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:490)
at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1105)
at android.support.v4.view.ViewPager.populate(ViewPager.java:951)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1473)
at android.view.View.measure(View.java:15172)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.view.View.measure(View.java:15172)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:833)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
at android.view.View.measure(View.java:15172)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2148)
at android.view.View.measure(View.java:15172)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1848)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1100)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1273)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:998)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4212)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
at android.view.Choreographer.doCallbacks(Choreographer.java:555)
at android.view.Choreographer.doFrame(Choreographer.java:525)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
at android.os.Handler.handleCallback(Handler.java:615)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4745)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：0)
问题出在onCreateView()。您正在使用getView().findViewById()中的onCreateView()查找观看次数。不推荐这种方法，我敢打赌你的getView()返回null。来自文档：
getView()
Get the root view for the fragment's layout (the one returned by onCreateView(LayoutInflater, ViewGroup, Bundle)), if provided.
getView()返回后， onCreateView()将为非空。
无需在getView()中使用onCreateView()。这样做：
txtName = (TextView) rootView.findViewById(R.id.name);
txtEmail = (TextView) rootView.findViewById(R.id.email);
btnLogout = (Button) rootView.findViewById(R.id.btnLogout);