java - Android - 二进制 XML 文件行 #19 : Error inflating class fragment

Question

我的 Android 应用程序开始给我 this (logcat)启动后出错。

我的主要 Activity 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 Activity xml here

我用谷歌搜索了很多，唯一的一件事是我发现了(使用extend FragmentActivity)，但是我的restoreActionBar()不起作用。在运行应用程序之前，Android studio 没有显示任何错误。

谢谢。

Answer 1

根据您的评论，我只有一个建议。

pixelsquad.csgohandbook.NavigationDrawerFragment 中的 Java fragment 代码是可疑的。为了隔离问题，您可以尝试另一个 fragment 代码吗？

创建 Activity 时，您需要调试 NavigationDrawerFragment，就像该 fragment 的 onCreate 一样。作为警告，如果该 fragment 不在同一项目中，则调试会更困难。

从 logcat 错误中，更深入地阅读它，我认为找不到类。错误:

Caused by: java.lang.ClassNotFoundException: Didn't find class "pixelsquad.csgohandbook.NavigationDrawerFragment"

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