java - ViewPager fragment 中的 ListView 为空白

Question

我在 ViewPager fragment 中有一个 ListView，当前应该由字符串数组填充，但它完全是空白的。这是该 fragment 的代码:

public class DirectoryFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_directory, container, false);

        ListView listView = (ListView) rootView.findViewById(R.id.list);

        String[] values = new String[] {"Viewer 1",
                                        "Viewer 2",
                                        "Viewer 3"
                                       };

        ArrayAdapter<String> adapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, android.R.id.text1, values);

        listView.setAdapter(adapter);

        return rootView;
    }

}

fragment 的 xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:background="#ff8400" >

    <ListView
        android:id="@+id/list"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:layout_marginTop="20dp">
    </ListView>


</RelativeLayout>

和MainActivity:

public class MainActivity extends FragmentActivity implements ActionBar.TabListener {

    private ViewPager viewPager;
    private TabsPagerAdapter mAdapter;
    private ActionBar actionBar;

    //Tab Titles
    private String[] tabs = { "sfn Viewer", "Directory", "Help" };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //Initialization
        viewPager = (ViewPager) findViewById(R.id.pager);
        actionBar = getActionBar();
        mAdapter = new TabsPagerAdapter(getSupportFragmentManager());

        viewPager.setAdapter(mAdapter);
        actionBar.setHomeButtonEnabled(false);
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

        //Adding Tabs
        for (String tab_name : tabs) {
            actionBar.addTab(actionBar.newTab().setText(tab_name).setTabListener(this));
        }

        viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
        public void onPageSelected(int position) {
                //On changing page, make sure right tab is selected
                actionBar.setSelectedNavigationItem(position);
            }

            @Override
            public void onPageScrolled(int arg0, float arg1, int arg2) {}

            @Override
            public void onPageScrollStateChanged(int arg0) {}
        });
    }


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

    @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();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
        //When the tab is selected show the correct fragment
        viewPager.setCurrentItem(tab.getPosition());
    }

    @Override
    public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {

    }

    @Override
    public void onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {

    }
}

我在 DirectoryFragment 选项卡中期望的是一个带有字符串 Viewer 1、Viewer 2 和 Viewer 3 的 ListView。

提前致谢!

Answer 1

您的 ListView 的 layout_height 在 XML 中为 0dp。将其更改为 match_parent 并删除 layout_weight，因为这在 RelativeLayout 中没有效果。