我是Android开发的新手。我已经为我的Activity创建了一个Tab导航，但是现在我将代码转移到我的Fragment for my project中，我遇到了一些错误。有人可以帮助我在片段中正确地做到这一点。
注意：我在frmSlide和fragmentFeedFragment上使用了import android.support.v4.app.Fragment;
我的frmSlide代码就是这个
public class frmSlide extends AppCompatActivity
implements NavigationDrawerFragment.NavigationDrawerCallbacks {
/**
* Fragment managing the behaviors, interactions and presentation of the navigation drawer.
*/
private NavigationDrawerFragment mNavigationDrawerFragment;
/**
* Used to store the last screen title. For use in {@link #restoreActionBar()}.
*/
private CharSequence mTitle;
ViewPager viewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_frm_slide);
mNavigationDrawerFragment = (NavigationDrawerFragment)
getSupportFragmentManager().findFragmentById(R.id.navigation_drawer);
mTitle = getTitle();
// Set up the drawer.
mNavigationDrawerFragment.setUp(
R.id.navigation_drawer,
(DrawerLayout) findViewById(R.id.drawer_layout));
}
@Override
public void onNavigationDrawerItemSelected(int position) {
FragmentManager fragmentManager = getSupportFragmentManager();
// update the main content by replacing fragments
fragmentManager.beginTransaction().replace(R.id.container, PlaceholderFragment.newInstance(position + 1)).commit();
Fragment fragment;
switch (position + 1) {
case 1:
//Profile
fragment = new fragmentProfileFragment();
fragmentManager.beginTransaction().replace(R.id.container, fragment).commit();
break;
case 2:
//startActivity(new Intent(this, fragmentFeed.class));
//Feed
fragment = new fragmentFeedFragment();
fragmentManager.beginTransaction().replace(R.id.container, fragment).commit();
break;
case 3:
//Settings
fragment = new fragmentSettingsFragment();
fragmentManager.beginTransaction().replace(R.id.container, fragment).commit();
break;
case 4:
//About
fragment = new fragmentAboutFragment();
fragmentManager.beginTransaction().replace(R.id.container, fragment).commit();
break;
}
Log.d("MySlide", "onNavigation " + position);
}
//SELECTED/CLICKED MENU ON SLIDE MENU
public void onSectionAttached(int number) {
switch (number) {
case 1:
mTitle = getString(R.string.title_section1);
//Toast.makeText(frmSlide.this, "Profile was selected", Toast.LENGTH_SHORT).show();
break;
case 2:
mTitle = getString(R.string.title_section2);
//Toast.makeText(frmSlide.this, "Feed was selected", Toast.LENGTH_SHORT).show();
break;
case 3:
mTitle = getString(R.string.title_section3);
//Toast.makeText(frmSlide.this, "Settings was selected", Toast.LENGTH_SHORT).show();
break;
case 4:
mTitle = getString(R.string.title_section4);
//Toast.makeText(frmSlide.this, "About was selected", Toast.LENGTH_SHORT).show();
break;
case 5:
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage("Are you sure you want to Logout?")
.setCancelable(false)
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
finish();
startActivity(new Intent(frmSlide.this, MainActivity.class));//Close this Activity for example: MyActivity.java
}
})
.setNegativeButton("No", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// some code if you want
dialog.cancel();
restoreActionBar();
}
});
AlertDialog alert = builder.create();
alert.show();
break;
}
}
public void restoreActionBar() {
ActionBar actionBar = getSupportActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
actionBar.setDisplayShowTitleEnabled(true);
actionBar.setTitle(mTitle);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
if (!mNavigationDrawerFragment.isDrawerOpen()) {
// Only show items in the action bar relevant to this screen
// if the drawer is not showing. Otherwise, let the drawer
// decide what to show in the action bar.
getMenuInflater().inflate(R.menu.frm_slide, menu);
restoreActionBar();
return true;
}
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_frm_slide, container, false);
return rootView;
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
((frmSlide) activity).onSectionAttached(
getArguments().getInt(ARG_SECTION_NUMBER));
}
}
}
这是我的fragmentFeedFragment。
public class fragmentFeedFragment extends Fragment implements ActionBar.TabListener {
ViewPager viewPager;
ActionBar actionBar;
public fragmentFeedFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.activity_fragment_feed, container, false);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
viewPager = (ViewPager) getView().findViewById(R.id.pager);
viewPager.setAdapter(new MyFeedAdapter(getFragmentManager()));
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
Log.d("Vivz", "onTabSelected at " + "position " + position + "from " + positionOffset + "pixels # " + positionOffsetPixels);
}
@Override
public void onPageSelected(int position) {
actionBar.setSelectedNavigationItem(position);
//Log.d("Vivz", "onTabSelected at " + "position " + position);
}
@Override
public void onPageScrollStateChanged(int state) {
}
});
actionBar = ((ActionBarActivity)getActivity()).getSupportActionBar();
//actionBar = getSupportActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
ActionBar.Tab tab1 = actionBar.newTab();
tab1.setText("JOY");
tab1.setTabListener(this);
ActionBar.Tab tab2 = actionBar.newTab();
tab2.setText("SADNESS");
tab2.setTabListener(this);
ActionBar.Tab tab3 = actionBar.newTab();
tab3.setText("ANGER");
tab3.setTabListener(this);
actionBar.addTab(tab1);
actionBar.addTab(tab2);
actionBar.addTab(tab3);
}
@Override
public void onTabSelected(ActionBar.Tab tab, FragmentTransaction ft) {
viewPager.setCurrentItem(tab.getPosition());
}
@Override
public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction ft) {
}
@Override
public void onTabReselected(ActionBar.Tab tab, FragmentTransaction ft) {
}
}
类MyFeedAdapter扩展了FragmentPagerAdapter {
public MyFeedAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
Fragment fragment = null;
if (position==0){
fragment = new fragmentJoyFragment();
}
if (position==1){
fragment = new fragmentSadnessFragment();
}
if (position==2){
fragment = new fragmentAngerFragment();
}
return fragment;
}
@Override
public int getCount() {
return 3;
}
}
这是出现的错误
10-15 11:11:37.781 16034-16034/com.example.agnes.myapplication E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.ClassCastException: com.example.agnes.myapplication.frmSlide cannot be cast to android.support.v7.app.ActionBarActivity
at com.example.agnes.myapplication.fragmentFeedFragment.onActivityCreated(fragmentFeedFragment.java:54)
at android.support.v4.app.Fragment.performActivityCreated(Fragment.java:1970)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1051)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1207)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1572)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:493)
at android.os.Handler.handleCallback(Handler.java:615)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:213)
at android.app.ActivityThread.main(ActivityThread.java:4787)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：1)
在fragmentFeedFragment.java:54中，
更改
actionBar = ((ActionBarActivity)getActivity()).getSupportActionBar();
致
actionBar = getActionBar();
答案 1 :(得分：0)
我通过将AppCompatActivity从我的frmSlide更改为ActionBarActivity来解决此问题。