我正在尝试实现选项卡导航，我有一个扩展 fragment Activity 的容器 Activity ，并且此 Activity 使用 ActionBar 创建了一个 TabView。该应用程序将尝试创建三个选项卡并将它们添加到 ActionBar，我想根据 TabSelection 更改 fragment 。但是发生错误 07-04 12:17:33.534: E/AndroidRuntime(795) : Caused by: java.lang.ClassCastException: com.freight.fragments.TruckStatus 无法转换为 android.support.v4.app.Fragment。
TruckActivity.java
package com.freight.activities;
import java.util.Locale;
import com.clacion.freightexchange.R;
import com.clacion.freightexchange.R.drawable;
import com.clacion.freightexchange.R.id;
import com.clacion.freightexchange.R.layout;
import com.clacion.freightexchange.R.menu;
import com.clacion.freightexchange.R.string;
import com.freight.fragments.TruckStatus;
import android.app.ActionBar;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.app.NavUtils;
import android.support.v4.view.ViewPager;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class TruckActivity extends FragmentActivity implements
ActionBar.TabListener {
/**
* The {@link android.support.v4.view.PagerAdapter} that will provide
* fragments for each of the sections. We use a
* {@link android.support.v4.app.FragmentPagerAdapter} derivative, which
* will keep every loaded fragment in memory. If this becomes too memory
* intensive, it may be best to switch to a
* {@link android.support.v4.app.FragmentStatePagerAdapter}.
*/
SectionsPagerAdapter mSectionsPagerAdapter;
/**
* The {@link ViewPager} that will host the section contents.
*/
ViewPager mViewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_truck);
// Set up the action bar.
final ActionBar actionBar = getActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
// Create the adapter that will return a fragment for each of the three
// primary sections of the app.
mSectionsPagerAdapter = new SectionsPagerAdapter(
getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mSectionsPagerAdapter);
// When swiping between different sections, select the corresponding
// tab. We can also use ActionBar.Tab#select() to do this if we have
// a reference to the Tab.
mViewPager
.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
@Override
public void onPageSelected(int position) {
actionBar.setSelectedNavigationItem(position);
}
});
// For each of the sections in the app, add a tab to the action bar.
for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) {
// Create a tab with text corresponding to the page title defined by
// the adapter. Also specify this Activity object, which implements
// the TabListener interface, as the callback (listener) for when
// this tab is selected.
actionBar.addTab(actionBar.newTab()
.setText(mSectionsPagerAdapter.getPageTitle(i))
.setIcon(R.drawable.item_menu_config)
.setTabListener(this));
}
actionBar.setSelectedNavigationItem(0);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.truck, menu);
return true;
}
@Override
public void onTabSelected(ActionBar.Tab tab,
FragmentTransaction fragmentTransaction) {
// When the given tab is selected, switch to the corresponding page in
// the ViewPager.
mViewPager.setCurrentItem(tab.getPosition());
}
@Override
public void onTabUnselected(ActionBar.Tab tab,
FragmentTransaction fragmentTransaction) {
}
@Override
public void onTabReselected(ActionBar.Tab tab,
FragmentTransaction fragmentTransaction) {
}
/**
* A {@link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the sections/tabs/pages.
*/
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a DummySectionFragment (defined as a static inner class
// below) with the page number as its lone argument.
Fragment fragment = new DummySectionFragment();
Bundle args = new Bundle();
args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, position + 1);
fragment.setArguments(args);
return fragment;
}
@Override
public int getCount() {
// Show 3 total pages.
return 3;
}
@Override
public CharSequence getPageTitle(int position) {
Locale l = Locale.getDefault();
switch (position) {
case 0:
return getString(R.string.title_menu_truck1).toUpperCase(l);
case 1:
return getString(R.string.title_menu_truck2).toUpperCase(l);
case 2:
return getString(R.string.title_menu_truck3).toUpperCase(l);
}
return null;
}
}
/**
* A dummy fragment representing a section of the app, but that simply
* displays dummy text.
*/
public static class DummySectionFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
public static final String ARG_SECTION_NUMBER = "section_number";
public DummySectionFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_truck_dummy,
container, false);
// TextView dummyTextView = (TextView) rootView
// .findViewById(R.id.section_label);
// dummyTextView.setText(Integer.toString(getArguments().getInt(
// ARG_SECTION_NUMBER)));
int pos=getArguments().getInt(ARG_SECTION_NUMBER);
if(pos==1){
// dummyTextView.setText("Selected Truck");
}else if(pos==2){
// dummyTextView.setText("Selected Tripsheet");
}else if(pos==3){
// dummyTextView.setText("Selected Alerts");
}
return rootView;
}
}
}
fragment_truck_dummy.xml
<RelativeLayout 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"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:background="#000"
tools:context=".TruckActivity$DummySectionFragment" >
<!-- <TextView
android:id="@+id/section_label"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#FFF" /> -->
<fragment
android:id="@+id/sub_frag"
android:layout_width="match_parent"
android:layout_height="match_parent"
class="com.freight.fragments.TruckStatus" />
</RelativeLayout>
TruckStatus.java
package com.freight.fragments;
import com.clacion.freightexchange.R;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class TruckStatus extends Fragment {
@Override
public void onActivityCreated(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onActivityCreated(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
View v =inflater.inflate(R.layout.truck_status_fragment,
container, false);
return v;
}
}
我的 LogCat
07-04 12:17:33.534: E/AndroidRuntime(795): FATAL EXCEPTION: main
07-04 12:17:33.534: E/AndroidRuntime(795): android.view.InflateException: Binary XML file line #17: Error inflating class fragment
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.LayoutInflater.rInflate(LayoutInflater.java:746)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
07-04 12:17:33.534: E/AndroidRuntime(795): at com.freight.activities.TruckActivity$DummySectionFragment.onCreateView(TruckActivity.java:177)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.support.v4.app.Fragment.performCreateView(Fragment.java:1460)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:911)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1088)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1444)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:461)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.support.v4.view.ViewPager.populate(ViewPager.java:1064)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.support.v4.view.ViewPager.populate(ViewPager.java:911)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1432)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.View.measure(View.java:15518)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.View.measure(View.java:15518)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.widget.LinearLayout.measureVertical(LinearLayout.java:847)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.View.measure(View.java:15518)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
07-04 12:17:33.534: E/AndroidRuntime(795): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2176)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.View.measure(View.java:15518)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1874)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1089)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1265)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.Choreographer.doCallbacks(Choreographer.java:562)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.Choreographer.doFrame(Choreographer.java:532)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.os.Handler.handleCallback(Handler.java:725)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.os.Handler.dispatchMessage(Handler.java:92)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.os.Looper.loop(Looper.java:137)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.app.ActivityThread.main(ActivityThread.java:5041)
07-04 12:17:33.534: E/AndroidRuntime(795): at java.lang.reflect.Method.invokeNative(Native Method)
07-04 12:17:33.534: E/AndroidRuntime(795): at java.lang.reflect.Method.invoke(Method.java:511)
07-04 12:17:33.534: E/AndroidRuntime(795): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
07-04 12:17:33.534: E/AndroidRuntime(795): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
07-04 12:17:33.534: E/AndroidRuntime(795): at dalvik.system.NativeStart.main(Native Method)
07-04 12:17:33.534: E/AndroidRuntime(795): Caused by: java.lang.ClassCastException: com.freight.fragments.TruckStatus cannot be cast to android.support.v4.app.Fragment
07-04 12:17:33.534: E/AndroidRuntime(795): at android.support.v4.app.Fragment.instantiate(Fragment.java:394)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.support.v4.app.Fragment.instantiate(Fragment.java:369)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:272)
07-04 12:17:33.534: E/AndroidRuntime(795): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:676)
07-04 12:17:33.534: E/AndroidRuntime(795): ... 43 more
我正在使用 Android 4.2.2 API 17..有人知道吗？
最佳答案
将导入从 android.app.Fragment 更改为 android.support.v4.app.Fragment 帮助我解决了这个问题。谢谢!
关于android - java.lang.ClassCastException :fragment cannot be cast to android. 支持.v4.app.Fragment，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/17470775/