我创建了一个包含选项卡视图和动态片段概念的应用程序。当我在按下选项卡时切换到不同的活动时，代码早些时候工作正常，但是当我将它转换为片段时，dushhhh。我知道处理片段和活动是两个不同的事情，但逻辑是相同的只是少数这里有变化，这里是代码。
The main layout is "activity_main.xml"
<TabHost
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@android:id/tabhost"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TabWidget
android:id="@android:id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="0"
android:orientation="horizontal" />
<FrameLayout
android:id="@+id/tabFrameLayout"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1" />
</LinearLayout>
</TabHost>
当用户按下任何选项卡时，我使用了两个片段来切换：其中一个片段布局是“googleMap.xml”：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView android:id="@+id/google_map"
android:layout_height="wrap_content"
android:layout_width="match_parent"
android:text="MAP"/>
</LinearLayout>
第二个片段是：“friends_list.xml”
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:id="@+id/textViewFriends"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="friends list will appear here" />
<ListView
android:id="@+id/friends_list"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
</ListView>
</LinearLayout>
主要活动是：“MainActivity.java”：
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentTabHost;
import com.example.friendsfinder.R;
public class MainActivity extends FragmentActivity {
private FragmentTabHost mTabHost;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setTabContent();
}
private void setTabContent() {
mTabHost = (FragmentTabHost) findViewById(android.R.id.tabhost);
mTabHost.setup(this, getSupportFragmentManager(), R.id.tabFrameLayout);
mTabHost.addTab(
mTabHost.newTabSpec("map").setIndicator("Map",
getResources().getDrawable(android.R.drawable.star_on)),
MapFragment.class, null);
mTabHost.addTab(
mTabHost.newTabSpec("friends list").setIndicator("Friends List",
getResources().getDrawable(android.R.drawable.star_on)),
FriendsListFragment.class, null);
}
}
第一个片段文件是“FriendsListFragment.java”：
import com.example.friendsfinder.R;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class FriendsListFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view=inflater.inflate(R.layout.friends_list, container,false);
return view;
}
}
第二个片段文件是：“MapFragment.java”：
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class MapFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view=inflater.inflate(R.layout.google_map, container,false);
return view;
}
}
即将出现的错误是：Logcat 条目是：
09-19 19:26:40.767: E/AndroidRuntime(28679): FATAL EXCEPTION: main
09-19 19:26:40.767: E/AndroidRuntime(28679): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.friendsfinder/com.webonise.friendsfinder.MainActivity}: java.lang.ClassCastException: android.widget.TabHost
09-19 19:26:40.767: E/AndroidRuntime(28679): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
09-19 19:26:40.767: E/AndroidRuntime(28679): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
09-19 19:26:40.767: E/AndroidRuntime(28679): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
09-19 19:26:40.767: E/AndroidRuntime(28679): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
09-19 19:26:40.767: E/AndroidRuntime(28679): at android.os.Handler.dispatchMessage(Handler.java:99)
09-19 19:26:40.767: E/AndroidRuntime(28679): at android.os.Looper.loop(Looper.java:130)
09-19 19:26:40.767: E/AndroidRuntime(28679): at android.app.ActivityThread.main(ActivityThread.java:3683)
09-19 19:26:40.767: E/AndroidRuntime(28679): at java.lang.reflect.Method.invokeNative(Native Method)
09-19 19:26:40.767: E/AndroidRuntime(28679): at java.lang.reflect.Method.invoke(Method.java:507)
09-19 19:26:40.767: E/AndroidRuntime(28679): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
09-19 19:26:40.767: E/AndroidRuntime(28679): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
09-19 19:26:40.767: E/AndroidRuntime(28679): at dalvik.system.NativeStart.main(Native Method)
09-19 19:26:40.767: E/AndroidRuntime(28679): Caused by: java.lang.ClassCastException: android.widget.TabHost
09-19 19:26:40.767: E/AndroidRuntime(28679): at com.webonise.friendsfinder.MainActivity.setTabContent(MainActivity.java:22)
09-19 19:26:40.767: E/AndroidRuntime(28679): at com.webonise.friendsfinder.MainActivity.onCreate(MainActivity.java:17)
09-19 19:26:40.767: E/AndroidRuntime(28679): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
09-19 19:26:40.767: E/AndroidRuntime(28679): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
09-19 19:26:40.767: E/AndroidRuntime(28679): ... 11 more
09-19 19:26:51.617: I/Process(28679): Sending signal. PID: 28679 SIG: 9