Android - 二进制 XML 文件第 19 行：膨胀类片段时出错

Question

我的安卓应用在启动后开始给我this (logcat) 错误。

我的主要活动是：

import android.app.Activity;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.support.v4.widget.DrawerLayout;

public class MainActivity extends AppCompatActivity
        implements my.app.NavigationDrawerFragment.NavigationDrawerCallbacks {

    /**
     * Fragment managing the behaviors, interactions and presentation of the navigation drawer.
     */
    private my.app.NavigationDrawerFragment mNavigationDrawerFragment;

    /**
     * Used to store the last screen title. For use in {@link #restoreActionBar()}.
     */
    private CharSequence mTitle;

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

        mNavigationDrawerFragment = (my.app.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) {

        Fragment myFragment = null;

        switch (position) {

            case 0:
                myFragment = new First_Fragment();
                break;

            case 1:
                myFragment = new Second_Fragment();
                break;

            case 2:
                myFragment = new Third_Fragment();
                break;

            case 3:
                myFragment = new Fourth_Fragment();
                break;
            //case 3:
            //    myFragment = new Caseopen_Fragment();
            //    break;
        }
        // update the main content by replacing fragments
        FragmentManager fragmentManager = getSupportFragmentManager();
        fragmentManager.beginTransaction()
                .replace(R.id.container, myFragment)
                .commit();
    }

    public void onSectionAttached(int number) {
        switch (number) {
            case 1:
                mTitle = getString(R.string.title_section1);
                break;
            case 2:
                mTitle = getString(R.string.title_section2);
                break;
            case 3:
                mTitle = getString(R.string.title_section3);
                break;
            case 4:
                mTitle = getString(R.string.title_section4);
                break;
            //case 4:
            //    mTitle = getString(R.string.title_caseopen);
            //    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.main, 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_main, container, false);
            return rootView;
        }

        @Override
        public void onAttach(Activity activity) {
            super.onAttach(activity);
            ((MainActivity) activity).onSectionAttached(
                    getArguments().getInt(ARG_SECTION_NUMBER));
        }
    }

}

主要活动 xml here

我用谷歌搜索了很多，唯一的东西，我发现（使用extend FragmentActivity）但是我的restoreActionBar() 不起作用。在我运行应用程序之前，Android Studio 没有显示任何错误。

谢谢。

Answer 1

从你们的cmets，我只有一个建议。

pixelsquad.csgohandbook.NavigationDrawerFragment 中的 Java 片段代码有嫌疑。为了隔离问题，您可以尝试另一个片段代码吗？

您需要在创建 Activity 时调试 NavigationDrawerFragment，例如该片段的 onCreate。如果该片段不在同一个项目中，则更难调试，作为警告。

从 logcat 错误，深入阅读，我认为 class is not found。错误：

原因：java.lang.ClassNotFoundException：找不到类 "pixelsquad.csgohandbook.NavigationDrawerFragment"

如果是这样，那么在系统 Java 路径中根本找不到类、JAR 或 APK 文件。

Answer 2

我已经解决了这个问题。我将属性 android:name 更改为类。 （尽管在 Android Document 上，他们说这些属性是相同的，但它可以工作！！！）

所以，它应该从：

 android:name="pixelsquad.csgohandbook.NavigationDrawerFragment"

到

class="pixelsquad.csgohandbook.NavigationDrawerFragment"

所以，新的布局应该是：

<FrameLayout android:id="@+id/container" android:layout_width="match_parent"
       android:layout_height="match_parent" />

    <!-- android:layout_gravity="start" tells DrawerLayout to treat
        this as a sliding drawer on the left side for left-to-right
        languages and on the right side for right-to-left languages.
        If you're not building against API 17 or higher, use
        android:layout_gravity="left" instead. -->
    <!-- The drawer is given a fixed width in dp and extends the full height of
        the container. -->
    <fragment android:id="@+id/navigation_drawer"
       android:layout_width="@dimen/navigation_drawer_width" android:layout_height="match_parent"
       android:layout_gravity="start"
       class ="pixelsquad.csgohandbook.NavigationDrawerFragment"
       tools:layout="@layout/fragment_navigation_drawer" />

希望有帮助:)