Question

我目前正在为学校目的创建一个Android应用程序。我的第一个问题是，我的导航抽屉出了问题。当我点击包含tablayout的“Home”时，应用程序崩溃了。这是我的导航抽屉的代码：

      public class NavigationDrawer extends AppCompatActivity{
      private static String tag = NavigationDrawer.class.getSimpleName();

private DrawerLayout mDrawer;
private Toolbar toolbar;
private NavigationView nvDrawer;
private ActionBarDrawerToggle DrawerToggle;
private CharSequence mTitle;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
setContentView(R.layout.drawer_layout);
mTitle="iGPH";
    toolbar = (Toolbar)findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    mDrawer = (DrawerLayout)findViewById(R.id.drawer_layout);
    // Find our drawer view
    nvDrawer = (NavigationView)findViewById(R.id.nvView);
    // Setup drawer view
    setupDrawerContent(nvDrawer);

    //Circular Image
    Bitmap bitmap = BitmapFactory.decodeResource(this.getResources(), R.drawable.logo);
    Bitmap circularBitmap = ImageConverter.getRoundedCornerBitmap(bitmap, 100);
    ImageView circularImageView = (ImageView)findViewById(R.id.avatar);
    circularImageView.setImageBitmap(circularBitmap);

   DrawerToggle = new ActionBarDrawerToggle(
            this,                  /* host Activity */
            mDrawer,         /* DrawerLayout object */
            toolbar,/* nav drawer icon to replace 'Up' caret */
            R.string.open,  /* "open drawer" description */
            R.string.close  /* "close drawer" description */
    ){
        public void onDrawerClosed(View view) {
            getActionBar().setTitle(mTitle);
        }

        /** Called when a drawer has settled in a completely open state. */
        public void onDrawerOpened(View drawerView) {
            getActionBar().setTitle(mTitle);
        }
    };
    }



private void setupDrawerContent(NavigationView navigationView) {
    navigationView.setNavigationItemSelectedListener(
            new NavigationView.OnNavigationItemSelectedListener() {
                @Override
                public boolean onNavigationItemSelected(MenuItem menuItem) {
                    selectDrawerItem(menuItem);

                    return true;
                }
            });

mDrawer.setDrawerListener(DrawerToggle);

getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);


}

public void selectDrawerItem(MenuItem menuItem) {
    // Create a new fragment and specify the planet to show based on
    // position
    android.support.v4.app.Fragment fragment = null;

    Class fragmentClass;
    switch(menuItem.getItemId()) {
        case R.id.Home:
            fragmentClass = Homepage.class;
            break;
        case R.id.Blog:
            fragmentClass = Fragment_Blog.class;
            break;
        case R.id.Planner:
            fragmentClass = VerificationPage.class;
            break;
        default:
            fragmentClass = VerificationPage.class;
    }

    try {
        fragment = (android.support.v4.app.Fragment) fragmentClass.newInstance();
    } catch (Exception e) {
        e.printStackTrace();
    }

    // Insert the fragment by replacing any existing fragment
    FragmentManager fragmentManager = getSupportFragmentManager();
    fragmentManager.beginTransaction().replace(R.id.flContent, fragment).commit();

    // Highlight the selected item, update the title, and close the drawer
    menuItem.setChecked(true);
    setTitle(menuItem.getTitle());
    mDrawer.closeDrawers();
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // The action bar home/up action should open or close the drawer.
    switch (item.getItemId()) {
        case android.R.id.home:
            mDrawer.openDrawer(GravityCompat.START);
            return true;
    }

    return super.onOptionsItemSelected(item);
}

// Make sure this is the method with just `Bundle` as the signature
@Override
protected void onPostCreate(Bundle savedInstanceState) {
    super.onPostCreate(savedInstanceState);
}
 }

这是我的主页代码：

      import android.app.ActionBar.Tab;
      import android.view.LayoutInflater;
      import android.view.View;
      import android.view.ViewGroup;

      public class Homepage extends Fragment implements TabListener {

private ViewPager viewPager;
private ActionBar actionBar;
private TabPagerAdapter tabPagerAdapter;
private String[] tabs = {"Luzon", "Visayas", "Mindanao"};

public Homepage() {
    // Required empty public constructor
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View view = inflater.inflate(R.layout.layout_homepage, container, false);

    viewPager = (ViewPager) view.findViewById(R.id.tabspager);
    tabPagerAdapter = new TabPagerAdapter(getFragmentManager());
    viewPager.setAdapter(tabPagerAdapter);
    final ActionBar actionBar = ((ActionBarActivity) getActivity()).getSupportActionBar();
    actionBar.setHomeButtonEnabled(false);
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_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 the page
            // make respected tab selected
            actionBar.setSelectedNavigationItem(position);
        }

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

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



@Override
public void onTabSelected(ActionBar.Tab tab, android.support.v4.app.FragmentTransaction ft) {

}

@Override
public void onTabUnselected(ActionBar.Tab tab, android.support.v4.app.FragmentTransaction ft) {

}

@Override
public void onTabReselected(ActionBar.Tab tab, android.support.v4.app.FragmentTransaction ft) {

}
      }

错误说：

NavigationDrawer无法强制转换为android.support.v7.app.ActionBarActivity

layout_homepage.xml

   <android.support.v4.view.ViewPager     xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:layout="http://schemas.android.com/apk/res-auto"
android:id="@+id/tabspager"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Fragment_Blog">
</android.support.v4.view.ViewPager>

TabPagerAdapter.class：

  public class TabPagerAdapter extends FragmentPagerAdapter {
public TabPagerAdapter(FragmentManager fm) {
    super(fm);
}

public Fragment getItem(int index) {

    switch (index) {
        case 0:
            // Top Rated fragment activity
            return new Fragment_luzon();
        case 1:
            // Games fragment activity
            return new Fragment_Visayas();
        case 2:
            // Movies fragment activity
            return new Fragment_Mindanao();
    }

    return null;
}

@Override
public int getCount() {
    // get item count - equal to number of tabs
    return 3;
}
}

Answer 1

对于错误（ NavigationDrawer无法转换为android.support.v7.app.ActionBarActivity ），请在此处进行修改：

final ActionBar actionBar = ((ActionBarActivity) getActivity()).getSupportActionBar();

作为

final ActionBar actionBar = ((AppCompatActivity) getActivity()).getSupportActionBar();

可能会有效。

（或者可能不需要施法：

final ActionBar actionBar = getActivity().getSupportActionBar();

）

因为您的Activity（NavigationDrawer）不是ActionBarActivity而是AppCompatActivity。

对于TabLayout问题：

你应该将TabLayout置于应放置的位置。例如：

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <android.support.design.widget.TabLayout
        android:id="@+id/tablayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <android.support.v4.view.ViewPager
        android:id="@+id/tabspager"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</LinearLayout>

在Java代码中，您可以将ViewPager设置为TabLayout。例如：

TabLayout tabLayout = (TabLayout) findViewById(R.id.tablayout);
ViewPager viewPager = (ViewPager) findViewById(R.id.tabspager);
tabLayout.setupWithViewPager(viewPager);

如需进一步使用或指导，请搜索StackOverflow Q＆amp; As及其他信息。

在工具栏中添加tablayout

1 个答案: