Question

所以我正在研究这个Android应用程序，我把NavigatonDrawer放进去，这很好用。当选择抽屉中的项目时，MainActivity应该替换FrameLayout，activity_main.xml在FrameLayout中定义。问题是，当我用片段替换@Override public void onNavigationDrawerItemSelected(int position) { FragmentTransaction transaction=getFragmentManager().beginTransaction(); switch (position){ case 0: //cal calFragment cal=new calFragment().newInstance(); transaction.replace(R.id.container, cal); break; case 1: //note noteFragment note=new noteFragment(); transaction.replace(R.id.container, note); break; case 2: //con conFragment con=new conFragment(); transaction.replace(R.id.container, con); break; case 3: //TODO login break; case 4: //TODO settings break; default:break; } transaction.commit(); }时，app force会关闭。我究竟做错了什么？我该如何解决这个问题？

这里是从抽屉中选择项目时调用的方法：

<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.arandum.syncc.MainActivity">

<!-- As the main content view, the view below consumes the entire
     space available using match_parent in both dimensions. -->
<FrameLayout
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

<fragment android:id="@+id/navigation_drawer"
    android:layout_width="@dimen/navigation_drawer_width"
    android:layout_height="match_parent"
    android:layout_gravity="start"
    android:name="com.arandum.syncc.NavigationDrawerFragment" />

这是activity_main.xml：

public class calFragment extends Fragment {

private OnFragmentInteractionListener mListener;

public static calFragment newInstance() {
    calFragment fragment = new calFragment();
    return fragment;
}
public calFragment() {
    // Required empty public constructor
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    return inflater.inflate(R.layout.fragment_cal, container, false);
}

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    try {
        mListener = (OnFragmentInteractionListener) activity;
    } catch (ClassCastException e) {
        throw new ClassCastException(activity.toString()
                + " must implement OnFragmentInteractionListener");
    }
}

@Override
public void onDetach() {
    super.onDetach();
    mListener = null;
}

public interface OnFragmentInteractionListener {

    public void onFragmentInteraction(Uri uri);
}

还有calFragment.java和fragment_cal.xml供参考

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.arandum.syncc.calFragment">

<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="@string/title_section1"
    android:textSize="30sp"
    />

}

    04-15 11:23:49.385  22325-22325/com.arandum.syncc D/dalvikvm﹕ Late-enabling CheckJNI
    04-15 11:23:49.445  22325-22325/com.arandum.syncc D/dalvikvm﹕ DexOpt: couldn't find field Landroid/app/ActivityThread;.mActiveResources
    04-15 11:23:49.445  22325-22325/com.arandum.syncc W/dalvikvm﹕ VFY: unable to resolve instance field 1
    04-15 11:23:49.445  22325-22325/com.arandum.syncc D/dalvikvm﹕ VFY: replacing opcode 0x54 at 0x0006
    04-15 11:23:49.445  22325-22325/com.arandum.syncc D/dalvikvm﹕ DexOpt: couldn't find field Landroid/app/ActivityThread;.mPackages
    04-15 11:23:49.445  22325-22325/com.arandum.syncc W/dalvikvm﹕ VFY: unable to resolve instance field 4
    04-15 11:23:49.445  22325-22325/com.arandum.syncc D/dalvikvm﹕ VFY: replacing opcode 0x54 at 0x0000
    04-15 11:23:49.560  22325-22325/com.arandum.syncc D/AndroidRuntime﹕ Shutting down VM
    04-15 11:23:49.560  22325-22325/com.arandum.syncc W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x41fd9ba8)
    04-15 11:23:49.565  22325-22325/com.arandum.syncc E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.arandum.syncc, PID: 22325
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.arandum.syncc/com.arandum.syncc.MainActivity}: java.lang.ClassCastException: com.arandum.syncc.MainActivity@42315fe8 must implement OnFragmentInteractionListener
                at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2207)
                at     android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2257)
                at android.app.ActivityThread.access$800(ActivityThread.java:135)
                at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
                at android.os.Handler.dispatchMessage(Handler.java:102)
                at android.os.Looper.loop(Looper.java:136)
                at android.app.ActivityThread.main(ActivityThread.java:5029)
                at java.lang.reflect.Method.invokeNative(Native Method)
                at java.lang.reflect.Method.invoke(Method.java:515)
                at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
                at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
                at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:132)
                at dalvik.system.NativeStart.main(Native Method)
         Caused by: java.lang.ClassCastException: com.arandum.syncc.MainActivity@42315fe8 must implement OnFragmentInteractionListener
                at com.arandum.syncc.calFragment.onAttach(calFragment.java:36)
            at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:849)
            at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1062)
            at android.app.BackStackRecord.run(BackStackRecord.java:684)
            at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1447)
            at android.app.Activity.performStart(Activity.java:6050)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2257)
            at android.app.ActivityThread.access$800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5029)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
            at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:132)
            at dalvik.system.NativeStart.main(Native Method)
04-15 11:23:51.490  22325-22325/com.arandum.syncc I/Process﹕ Sending signal. PID: 22325 SIG: 9

提前致谢！

新

{{1}}

Answer 1

要拨打FragmentTransaction并添加/替换/显示/隐藏 Fragment，您需要按以下方式执行commit：

fragmentManager.beginTransaction().replace(R.id.container, cal).commit();

然后，您的代码应使用Fragment的常规变量：

FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransac = fragmentManager.beginTransaction();
// init the fragment (with the a default fragment, not null)
Fragment frag = new calFragment().newInstance();
switch (position){
    case 0:
        // init with the 1st fragment
        frag = new calFragment().newInstance();
        break;
    case 1:
        // init with the 2nd fragment
        frag = new noteFragment();
        break;
    case 2:
        // same for others
        frag = new conFragment();
        break;
    case 3: //TODO login
        break;
    case 4: //TODO settings
        break;
    default:break;
}
// THEN replace with the fragment variable
fragmentTransac.replace(R.id.container, frag, null);
// commit the transaction
fragmentTransac.commit();

正如您的Logcat所说：com.arandum.syncc.MainActivity@42316ed0 must implement OnFragmentInteractionListener然后尝试添加此实现：

public class MainActivity extends FragmentActivity (or ActionBarActivity) implements calFragment.OnFragmentInteractionListener {

对于每个Fragment将使用一个，您必须在Interface内实现自己的MainActivity，如下所示：

implements calFragment.OnFragmentInteractionListener, noteFragment.PublicInterface, conFragment.AnotherInterface, ...etc

Answer 2

你需要

FramentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.commit();

要将事务应用于活动，必须调用commit（）。

@Override
public void onNavigationDrawerItemSelected(int position) {

FragmentManager fragmentManager = getFragmentManager();
FramentTransaction fragmentTransaction = fragmentManager.beginTransaction();
switch (position){
    case 0: //cal
        calFragment cal=new calFragment().newInstance();
        fragmentTransaction.replace(R.id.container, cal);
        fragmentTransaction.commit();  
        break;
    case 1: //note
        noteFragment note=new noteFragment();
        fragmentTransaction.replace(R.id.container, note);
        fragmentTransaction.commit();
        break;
    case 2: //con
        conFragment con=new conFragment();
        fragmentTransaction.replace(R.id.container, con);
        fragmentTransaction.commit();
        break;
    case 3: //TODO login
        break;
    case 4: //TODO settings
        break;
    default:break;
}

片段UI未显示

2 个答案: