我有一个包含两个活动（MainActivity 和 WelcomeActividy）的应用程序都从android.support.v4.app.FragmentActivity
WelcomeActivity 使用 ViewFlipper 在一个 Step 中显示 Fragments (Step1, Step2, ..., StepN) 使用片段列表 (CategoryStarredFragment) WelcomeActivity 没有问题
MainActivity 使用 tabhost 来显示片段也可以正常工作，但是当尝试包含相同的 CategoryStarredFragment （在 WelcomeActivity 中工作正常）时，我得到了一个异常
04-11 15:32:28.197: E/AndroidRuntime(16124): Caused by: java.lang.ClassNotFoundException: android.view.fragment in loader dalvik.system.PathClassLoader[/data/app/com.package.apk]
我在想这是产生问题的tabhost的实现
这里是MainActivity.java
public class MainActivity extends FragmentActivity implements OnTabChangeListener {
private TabHost mTabHost;
private SparseArray<Class<?>> mSparseFragments = new SparseArray<Class<?>>(){{
put(R.id.tab_home, HomeFragment.class);
// other tabs
put(R.id.tab_settings, SettingsFragment.class);
}};
private SparseArray<String> mSparseTags = new SparseArray<String>(){{
put(R.id.tab_home, "home");
// other tabs
put(R.id.tab_settings, "settings");
}};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initTabs();
}
private void initTabs() {
mTabHost = (TabHost)findViewById(android.R.id.tabhost);
mTabHost.setup();
mTabHost.setOnTabChangedListener(this);
mTabHost.addTab(buildTabSpec("home", R.string.title_tab_home, R.layout.regular_home_fragment));
// other tabs
mTabHost.addTab(buildTabSpec("settings", R.string.title_tab_settings, R.layout.regular_settings_fragment));
}
@Override
public void onTabChanged(String tabId) {
Log.i(TAG, "Tab changed to: " + tabId);
final FragmentManager fm = getSupportFragmentManager();
final FragmentTransaction ft = fm.beginTransaction();
Fragment fragment;
int current = 0;
for (int i = R.id.tab_home; i <= R.id.tab_settings; i++) {
if(mSparseTags.get(i).equals(tabId)) {
current = i;
} else if(null != (fragment = fm.findFragmentByTag(mSparseTags.get(i)))) {
ft.detach(fragment);
}
}
if(null == (fragment = fm.findFragmentByTag(tabId))) {
try {
ft.add(current, (Fragment) mSparseFragments.get(current).newInstance(), tabId);
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
} else {
ft.attach(fragment);
}
ft.commit();
}
private TabSpec buildTabSpec(String tag, int labelId, int viewId) {
final View indicator = LayoutInflater.from(getApplicationContext())
.inflate(R.layout.tab, (ViewGroup) findViewById(android.R.id.tabs), false);
((TextView)indicator.findViewById(R.id.text)).setText(labelId);
return mTabHost.newTabSpec(tag)
.setIndicator(indicator)
.setContent(new TabContent(getApplicationContext(), viewId));
}
public class TabContent implements TabContentFactory {
private Context mContext;
private int mViewId;
public TabContent(Context context, int viewId) {
mContext = context;
mViewId = viewId;
}
@Override
public View createTabContent(String tag) {
Log.i(TAG, "Inflation tab content " + tag);
View view = LayoutInflater.from(mContext).inflate(mViewId, null);
return view;
}
}
}
这是 MainActivity 布局
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
tools:context=".MainActivity" >
<TabHost
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@android:id/tabhost">
<LinearLayout
android:orientation="vertical"
android:layout_height="fill_parent"
android:layout_width="fill_parent">
<TabWidget
android:id="@android:id/tabs"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="@drawable/ab_stacked_solid_mainbar">
</TabWidget>
<FrameLayout
android:id="@android:id/tabcontent"
android:layout_height="fill_parent"
android:layout_width="fill_parent">
<FrameLayout
android:id="@+id/tab_home"
android:layout_height="fill_parent"
android:layout_width="fill_parent"/>
<!-- Other tabs -->
<FrameLayout
android:id="@+id/tab_settings"
android:layout_height="fill_parent"
android:layout_width="fill_parent"/>
</FrameLayout>
</LinearLayout>
</TabHost>
</RelativeLayout>
这是布局第一个选项卡
<?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/title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center_horizontal"
android:text="@string/title_tab_home"
android:textSize="64sp"/>
<fragment
android:id="@+id/category_list"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="5dp"
android:layout_marginTop="18dp"
class="com.package.CategoryStarredFragment" />
</LinearLayout>