第一次使用 Fragment，当我尝试使用 fragmentTransaction 打开它时得到 "Application has stopped"

Question

在我的片段中 Activity 我这样做了：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    FragmentManager fragmentManager = getFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
    principalFragment hello = principalFragment.newInstance();
    fragmentTransaction.add(R.id.fragment_container, hello, hello.TAG);
    fragmentTransaction.commit();

}

这是我要打开的片段

<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="plenumsoft.iniciativayucatan.ui.principal">


    <RelativeLayout
        android:layout_width="fill_parent"
        android:layout_height="135dp"

        android:background="@color/colorTerracota"
        android:padding="15dp"
        android:layout_centerVertical="true"
        android:layout_centerHorizontal="true"
        android:layout_gravity="center">

        <Button
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="@string/statetexas"
            android:id="@+id/btnTexas"
            android:width="100dp"
            android:layout_alignParentBottom="true"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true" />

        <Button
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="@string/stateyucatan"
            android:id="@+id/btnYucatan"
            android:width="100dp"
            android:layout_alignParentTop="true"
            android:layout_alignLeft="@+id/btnTexas"
            android:layout_alignStart="@+id/btnTexas" />


    </RelativeLayout>
</FrameLayout>

如果我创建一个新片段，我会得到相同的结果（默认情况下 android studio 使用 "hello blank fragment"）

如果我将 <fragment> 添加到 activity

，我会得到相同的结果

是logcat

01-06 06:21:00.990 3196-3196/? D/dalvikvm: Late-enabling CheckJNI 
01-06 06:21:01.290 3196-3196/soft.ini W/ActivityThread: Application soft.ini is waiting for the debugger on port 8100... 
01-06 06:21:01.310 3196-3196/soft.ini I/System.out: Sending WAIT chunk 
01-06 06:21:01.450 3196-3203/soft.ini I/dalvikvm: Debugger is active 
01-06 06:21:01.510 3196-3196/soft.ini I/System.out: Debugger has connected 
01-06 06:21:01.510 3196-3196/soft.ini I/System.out: waiting for debugger to settle... 
01-06 06:21:01.711 3196-3196/soft.ini I/System.out: waiting for debugger to settle... 
01-06 06:21:01.911 3196-3196/soft.ini I/System.out: waiting for debugger to settle... 
01-06 06:21:02.111 3196-3196/soft.ini I/System.out: waiting for debugger to settle... 
01-06 06:21:02.311 3196-3196/soft.ini I/System.out: waiting for debugger to settle... 
01-06 06:21:02.511 3196-3196/soft.ini I/System.out: waiting for debugger to settle... 
01-06 06:21:02.711 3196-3196/soft.ini I/System.out: waiting for debugger to settle... 
01-06 06:21:02.912 3196-3196/soft.ini I/System.out: waiting for debugger to settle... 
01-06 06:21:03.112 3196-3196/soft.ini I/System.out: debugger has settled (1428) 
01-06 06:21:03.602 3196-3196/soft.ini D/roboguice.RoboGuice: Using annotation database(s). 
01-06 06:21:03.612 3196-3196/soft.ini D/roboguice.RoboGuice: Using annotation database(s) : [, roboguice] 
01-06 06:21:03.632 3196-3196/soft.ini D/roboguice.RoboGuice: Time spent loading annotation databases : 17 
01-06 06:21:03.783 3196-3198/soft.ini D/dalvikvm: GC_CONCURRENT freed 302K, 13% free 9449K/10823K, paused 16ms+13ms, total 74ms 
01-06 06:21:04.623 3196-3198/soft.ini D/dalvikvm: GC_CONCURRENT freed 357K, 14% free 9539K/11015K, paused 19ms+23ms, total 113ms 
01-06 06:21:05.895 3196-3196/soft.ini D/dalvikvm: GC_FOR_ALLOC freed 52K, 14% free 9557K/11015K, paused 57ms, total 63ms 
01-06 06:21:06.195 3196-3196/soft.ini I/dalvikvm-heap: Grow heap (frag case) to 26.000MB for 16384016-byte allocation 
01-06 06:21:06.345 3196-3198/soft.ini D/dalvikvm: GC_CONCURRENT freed <1K, 6% free 25557K/27079K, paused 12ms+6ms, total 146ms 
01-06 06:21:06.345 3196-3203/soft.ini D/dalvikvm: WAIT_FOR_CONCURRENT_GC blocked 50ms 
01-06 06:21:06.445 3196-3196/soft.ini D/dalvikvm: GC_FOR_ALLOC freed <1K, 6% free 25557K/27079K, paused 20ms, total 20ms 
01-06 06:21:06.605 3196-3196/soft.ini I/dalvikvm-heap: Grow heap (frag case) to 61.156MB for 36864016-byte allocation 
01-06 06:21:06.665 3196-3198/soft.ini I/dalvikvm-heap: Clamp target GC heap from 64.156MB to 64.000MB 
01-06 06:21:06.665 3196-3198/soft.ini D/dalvikvm: GC_CONCURRENT freed 0K, 3% free 61557K/63111K, paused 13ms+14ms, total 53ms 
01-06 06:21:11.510 3196-3196/soft.ini D/AndroidRuntime: Shutting down VM 
01-06 06:21:11.510 3196-3196/soft.ini W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x419252a0)

这里开始红字

01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime: FATAL EXCEPTION: main 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime: java.lang.RuntimeException: Unable to start activity ComponentInfo{soft.ini/soft.ini.ui.content}: java.lang.ClassCastException: soft.ini.ui.content@4235a0e8 must implement OnFragmentInteractionListener 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2092) 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2117) 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at android.app.ActivityThread.access0(ActivityThread.java:134) 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1218) 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:99) 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:137) 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:4867) 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method) 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:511) 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1007) 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:774) 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at dalvik.system.NativeStart.main(Native Method) 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:  Caused by: java.lang.ClassCastException: soft.ini.ui.content@4235a0e8 must implement OnFragmentInteractionListener 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at soft.ini.ui.principalFragment.onAttach(principalFragment.java:83) 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:787) 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1035) 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at android.app.BackStackRecord.run(BackStackRecord.java:635) 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1399) 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at android.app.Activity.performStart(Activity.java:5056) 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2065) 
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2117)  
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at android.app.ActivityThread.access0(ActivityThread.java:134)  
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1218)  
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:99)  
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:137)  
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:4867)  
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method)  
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:511)  
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1007)  
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:774)  
01-06 06:21:11.940 3196-3196/soft.ini E/AndroidRuntime:     at dalvik.system.NativeStart.main(Native Method)

Answer 1

Caused by: java.lang.ClassCastException: soft.ini.ui.content@4235a0e8 must implement OnFragmentInteractionListener

您的主机 Activity 必须实现 principalFragment 的 OnFragmentInteractionListener:

public class YourActivity implements principalFragment.OnFragmentInteractionListener {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        FragmentManager fragmentManager = getFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        principalFragment hello = principalFragment.newInstance();
        fragmentTransaction.replace(R.id.fragment_container, hello, hello.TAG);
        fragmentTransaction.commit();
    }

    ...
    // Implement the listener's methods
    // @Override
}

并实现其方法。另外，使用 FragmentTransaction 的 replace 方法，而不是 add().

第一次使用 Fragment，当我尝试使用 fragmentTransaction 打开它时得到 "Application has stopped"

First time Fragment, and I got "Application has stopped" when I try open it with fragmentTransaction

java

android

fragment

android-fragments