Android Actionbar替换片段被调用为不显示任何内容

Question

我完全迷路了，这么简单的事情怎么会这么难做？我有一个带有片段的MainActivity(id:listfragment)。当活动开始时，显示一个包含新闻项目的列表。我只想在选择一个选项卡时用另一个选项卡替换列表。我希望这就足够了：

@Override
public void onTabSelected(Tab tab, FragmentTransaction fragmentTransaction) {
// TODO Auto-generated method stub
switch(tab.getPosition()) {
case 0:
Toast.makeText(this, "Tab News", Toast.LENGTH_SHORT).show();
// News
Fragment nfragment = new NewsList();
fragmentTransaction.replace(R.id.listfragment, nfragment);
break;
case 1:
Toast.makeText(this, "Tab Videos", Toast.LENGTH_SHORT).show();
// Videos
Fragment vfragment = new YoutubeList();
fragmentTransaction.replace(R.id.listfragment, vfragment);
}
}

新的片段被调用(我检查了添加日志)，但没有显示布局。有人能帮我摆脱痛苦吗？)

我试着添加了.commit()。立即崩溃了应用程序。我知道commit是自动调用的(正如他们在de Android文档中所说的那样)，但我不明白为什么它没有显示任何内容。

添加.commit()后的日志：

03-01 09:43:00.736: D/dalvikvm(4509): GC_FOR_ALLOC freed 79K, 14% free 10147K/11732K, paused 28ms, total 29ms
03-01 09:43:00.736: I/dalvikvm-heap(4509): Grow heap (frag case) to 12.450MB for 1127536-byte allocation
03-01 09:43:00.756: D/dalvikvm(4509): GC_FOR_ALLOC freed <1K, 13% free 11248K/12836K, paused 19ms, total 19ms
03-01 09:43:00.776: D/AbsListView(4509): Get MotionRecognitionManager
03-01 09:43:00.821: D/AndroidRuntime(4509): Shutting down VM
03-01 09:43:00.821: W/dalvikvm(4509): threadid=1: thread exiting with uncaught exception (group=0x41a03700)
03-01 09:43:00.821: E/AndroidRuntime(4509): FATAL EXCEPTION: main
03-01 09:43:00.821: E/AndroidRuntime(4509): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.switchingbrains.xxx.MainActivity}: java.lang.IllegalStateException: commit already called
03-01 09:43:00.821: E/AndroidRuntime(4509):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2308)
03-01 09:43:00.821: E/AndroidRuntime(4509):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2362)
03-01 09:43:00.821: E/AndroidRuntime(4509):     at android.app.ActivityThread.access$700(ActivityThread.java:168)
03-01 09:43:00.821: E/AndroidRuntime(4509):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1329)
03-01 09:43:00.821: E/AndroidRuntime(4509):     at android.os.Handler.dispatchMessage(Handler.java:99)
03-01 09:43:00.821: E/AndroidRuntime(4509):     at android.os.Looper.loop(Looper.java:137)
03-01 09:43:00.821: E/AndroidRuntime(4509):     at android.app.ActivityThread.main(ActivityThread.java:5493)
03-01 09:43:00.821: E/AndroidRuntime(4509):     at java.lang.reflect.Method.invokeNative(Native Method)
03-01 09:43:00.821: E/AndroidRuntime(4509):     at java.lang.reflect.Method.invoke(Method.java:525)
03-01 09:43:00.821: E/AndroidRuntime(4509):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1209)
03-01 09:43:00.821: E/AndroidRuntime(4509):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1025)
03-01 09:43:00.821: E/AndroidRuntime(4509):     at dalvik.system.NativeStart.main(Native Method)
03-01 09:43:00.821: E/AndroidRuntime(4509): Caused by: java.lang.IllegalStateException: commit already called
03-01 09:43:00.821: E/AndroidRuntime(4509):     at android.app.BackStackRecord.commitInternal(BackStackRecord.java:582)
03-01 09:43:00.821: E/AndroidRuntime(4509):     at android.app.BackStackRecord.commit(BackStackRecord.java:574)
03-01 09:43:00.821: E/AndroidRuntime(4509):     at com.android.internal.app.ActionBarImpl.selectTab(ActionBarImpl.java:608)
03-01 09:43:00.821: E/AndroidRuntime(4509):     at com.android.internal.app.ActionBarImpl.addTab(ActionBarImpl.java:532)
03-01 09:43:00.821: E/AndroidRuntime(4509):     at com.android.internal.app.ActionBarImpl.addTab(ActionBarImpl.java:518)
03-01 09:43:00.821: E/AndroidRuntime(4509):     at com.switchingbrains.xxx.MainActivity.onCreate(MainActivity.java:29)
03-01 09:43:00.821: E/AndroidRuntime(4509):     at android.app.Activity.performCreate(Activity.java:5372)
03-01 09:43:00.821: E/AndroidRuntime(4509):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1104)
03-01 09:43:00.821: E/AndroidRuntime(4509):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2270)
03-01 09:43:00.821: E/AndroidRuntime(4509):     ... 11 more

Answer 1

如果使用fragment标记在xml中定义片段，则无法在运行时替换它。尝试使用FrameLayout，并使用相同的id。

你可能有这样的东西：

<fragment ....
android:id="@+id/listfragment"
....  />

更改为：

<FrameLayout ....
android:id="@+id/listfragment"
....  />