为什么我的片段不被视为片段?它说类型不匹配:无法从MapScreen转换为Fragment

时间:2013-11-15 16:12:48

标签: android android-fragments

我正在使用Google Maps API V2并将地图放入片段......该文件中没有错误,但当我尝试将其放入我的标签切换器时,该类不会被视为片段。

public class MapScreen extends Fragment {
    // ...
  static final LatLng HAMBURG = new LatLng(53.558, 9.927);
          static final LatLng KIEL = new LatLng(53.551, 9.993);
          private GoogleMap map;

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        View v = inflater.inflate(R.layout.map_activity, null, false);

        map = ((MapFragment) getFragmentManager().findFragmentById(R.id.map)).getMap();

            Marker hamburg = map.addMarker(new MarkerOptions().position(HAMBURG)
                .title("Hamburg"));
            Marker kiel = map.addMarker(new MarkerOptions()
                .position(KIEL)
                .title("Kiel")
                .snippet("Kiel is cool")
                .icon(BitmapDescriptorFactory
                    .fromResource(R.drawable.ic_launcher)));

            // Move the camera instantly to hamburg with a zoom of 15.
            map.moveCamera(CameraUpdateFactory.newLatLngZoom(HAMBURG, 15));

            // Zoom in, animating the camera.
            map.animateCamera(CameraUpdateFactory.zoomTo(10), 2000, null);

        //...

        return v;
    }
}

那里似乎没有问题但是我的Dashboard类中出现了错误

public class Dashboard 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_dashboard);

        // 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))
                            .setTabListener(this));
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.dashboard, 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);

            switch (position) {
            case 0:

                return fragment;
            case 1:
                //Error Here
                **return new MapScreen();**
            case 2:

                  return fragment;
            }

            return null;
        }

        @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_section1).toUpperCase(l);
                case 1:
                    return getString(R.string.title_section2).toUpperCase(l);
                case 2:
                    return getString(R.string.title_section3).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_dashboard_dummy, container, false);
            TextView dummyTextView = (TextView) rootView.findViewById(R.id.section_label);
            dummyTextView.setText(Integer.toString(getArguments().getInt(ARG_SECTION_NUMBER)));
            return rootView;
        }
    }

}

我不确定这是如何被视为片段的?


package com.thinknew.battlemaps;
import com.google.android.gms.maps.*;
import com.google.android.gms.maps.model.*;
import android.app.Activity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.support.v4.app.Fragment;


public class MapScreen extends MapFragment {
    // ...
  static final LatLng HAMBURG = new LatLng(53.558, 9.927);
          static final LatLng KIEL = new LatLng(53.551, 9.993);
          private GoogleMap map;

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        View view = super.onCreateView(inflater,container,savedInstanceState);

        getMap();

            Marker hamburg = map.addMarker(new MarkerOptions().position(HAMBURG)
                .title("Hamburg"));
            Marker kiel = map.addMarker(new MarkerOptions()
                .position(KIEL)
                .title("Kiel")
                .snippet("Kiel is cool")
                .icon(BitmapDescriptorFactory
                    .fromResource(R.drawable.ic_launcher)));

            // Move the camera instantly to hamburg with a zoom of 15.
            map.moveCamera(CameraUpdateFactory.newLatLngZoom(HAMBURG, 15));

            // Zoom in, animating the camera.
            map.animateCamera(CameraUpdateFactory.zoomTo(10), 2000, null);

        //...

        return view;
    }
}

3 个答案:

答案 0 :(得分:2)

要使用v2,您的片段需要扩展SupportMapFragment而不是Fragment

然后在onCreateView中,在致电超级视图后调用getMap()

View view = super.onCreateView(inflater,container,savedInstanceState)

onCreateView应如下所示

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

    View view = super.onCreateView(inflater,container,savedInstanceState);
    map = getMap();
    //anything else you need to do
    return view;
}

答案 1 :(得分:0)

我可能错了,但我认为你正在尝试使用支持库的MapScreen片段,而eclipse确实导入了android.app.fragment。由于我在阅读你的评论后看不到为MapScreen导入的内容,我只猜测这个。

答案 2 :(得分:0)

您的MapScreen必须延长SupportMapFragment,而不是MapFragment