java.lang.ClassCastException：片段无法强制转换为android.support.v4.app.Fragment

时间：2013-07-04 12:49:03

标签： android android-fragments android-actionbar android-fragmentactivity android-support-library

我正在尝试实现Tab Navigation，我有一个扩展Fragment Activity的Container Activity，而这个Activity使用ActionBar创建一个TabView。该应用程序将尝试创建三个选项卡并将其添加到ActionBar，我想根据TabSelection更改片段。但是发生错误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。

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

使用Android 4.2.2 API 17 ..有没有人知道它？

4 个答案:

答案 0 :(得分：10)

将导入从android.app.Fragment更改为android.support.v4.app.Fragment有助于我解决此问题。谢谢！

答案 1 :(得分：8)

将导入import android.app.Fragment;更改为import android.support.v4.app.Fragment;到TruckStatus

答案 2 :(得分：1)

import android.support.v4.app.Fragment;

在您执行此操作之前右键单击project-＆gt; properties-＆gt; buildpath-＆gt; java build path - ＆gt;库..然后点击添加外部罐子

转到

user\android-sdks\extras\android\support\v4

并选择 android-support-v4.jar

答案 3 :(得分：0)

@lakvin如何说你可以改变： 1）android.app.Fragment =＆gt; support.v4.app.Fragment 我改变了 2）android.support.v4.app.FragmentTransaction; 3）实现android.app.ActionBar.TabListener

但是请确保您的主题可以处理ActionBar： 1）styles.xml和我把我改成了android：Theme.Material.Light甚至你可以使用Theme.Holo ......。

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