java - inflater.inflate() 方法调用时出现 InflateException

Question

在我的 MenuAdapter 类中尝试膨胀 View 时，我不断收到 InflateException。我将麻烦的代码包围在 try-catch block 中并收到错误消息:

整个项目的链接:

https://docs.google.com/file/d/0B2Iwl4UysxOMa3E5a1l2SHZwOG8/edit?usp=sharing

Binary XML file line #1: Error inflating class

代码如下:

package com.example.sidemenututorial;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

public class MenuListAdapter extends BaseAdapter {

    // Fields -----------------------------------------------------------------
    private Context context;
    private String[] titles;
    private String[] subtitles;
    private int[] icons;
    private LayoutInflater inflater;

    // Constructor ------------------------------------------------------------
    public MenuListAdapter(
            Context context, 
            String[] titles, 
            String[] subtitles,
            int[] icons){
        this.context = context;
        this.titles = titles;
        this.subtitles = subtitles;
        this.icons = icons;
        inflater = (LayoutInflater)context.getSystemService(
                Context.LAYOUT_INFLATER_SERVICE);
    }

    // Accessors --------------------------------------------------------------
    @Override
    public int getCount(){
        return titles.length;
    }
    @Override
    public Object getItem(int position){
        return titles[position];
    }
    @Override
    public long getItemId(int position){
        return position;
    }

    // Methods ----------------------------------------------------------------
    public View getView(int position, View convertView, ViewGroup parent){

        ViewHolder viewHolder;

        // Only inflate the view if convertView is null
        if (convertView == null){
            viewHolder = new ViewHolder();
            convertView = inflater.inflate(
                    R.layout.drawer_list_item, parent, false);
            viewHolder.txtTitle = (TextView)convertView.findViewById(
                    R.id.title);
            viewHolder.txtSubtitle = (TextView)convertView.findViewById(
                    R.id.subtitle);
            viewHolder.imgIcon = (ImageView)convertView.findViewById(
                    R.id.icon);

            // This is the first time this view has been inflated,
            // so store the view holder in its tag fields
            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder)convertView.getTag();
        }

        // Set the views fields as needed
        viewHolder.txtTitle.setText(titles[position]);
        viewHolder.txtSubtitle.setText(subtitles[position]);
        viewHolder.imgIcon.setImageResource(icons[position]);

        return convertView;
    }

    // Classes ----------------------------------------------------------------
    static class ViewHolder {
        TextView txtTitle;
        TextView txtSubtitle;
        ImageView imgIcon;
    }

}

And here is the view it is trying to inflate, the drawer_list_item.xml:

        <LinearLayout 
        xmlns:android="http://schemas.android.com/apk/res/android"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="?android:color/darker_gray"
            android:orientation="horizontal"
            style="?attr/dropdownListPreferredItemHeight" >

        <ImageView
            android:id="@+id/icon"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:adjustViewBounds="true"/>

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:gravity="center_vertical|left"
            android:orientation="vertical">

            <TextView
                android:id="@+id/title"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:ellipsize="end"
                android:singleLine="true"
                style="?attr/spinnerDropDownItemStyle"/>
            <TextView 
                android:id="@+id/subtitle"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:ellipsize="end"
                android:singleLine="true"
                android:textAppearance="?attr/textAppearanceSmall"
                style="?attr/spinnerDropDownItemStyle"/>

        </LinearLayout>    

    </LinearLayout>

下面是调用菜单适配器的客户端代码:

        package com.example.sidemenututorial;

    import android.content.res.Configuration;
    import android.os.Bundle;
    import android.support.v4.app.ActionBarDrawerToggle;
    import android.support.v4.app.Fragment;
    import android.support.v4.app.FragmentTransaction;
    import android.support.v4.view.GravityCompat;
    import android.support.v4.widget.DrawerLayout;
    import android.view.View;
    import android.widget.AdapterView;
    import android.widget.ListView;

    import com.actionbarsherlock.app.SherlockFragmentActivity;
    import com.actionbarsherlock.view.MenuItem;

    public class MainActivity extends SherlockFragmentActivity {

        // Fields -----------------------------------------------------------------
        private DrawerLayout drawerLayout;
        private ListView drawerList;
        private ActionBarDrawerToggle drawerToggle;
        private MenuListAdapter menuAdapter;
        private int[] icons;
        private Fragment fragment1;
        private Fragment fragment2;
        private Fragment fragment3;
        private CharSequence drawerTitle;
        private CharSequence title;
        private final String[] titles = new String[]{
                "Title Fragment #1",
                "Title Fragment #2",
                "Title Fragment #3"
        };
        private final String[] subtitles = new String[]{
                "Subtitle Fragment #1",
                "Subtitle Fragment #2",
                "Subtitle Fragment #3"
        };

        // Lifecycle Callbacks ----------------------------------------------------
        @Override
        protected void onCreate(Bundle savedInstanceState) {

            // Base implemenation
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);

            // Instantiate the fragments
            fragment1 = new Fragment1();
            fragment2 = new Fragment2();
            fragment3 = new Fragment3();

            // Get the title from this activity
            title = drawerTitle = getTitle();

            // Get the icons from the drawables folder
            icons = new int[]{
                    R.drawable.action_about,
                    R.drawable.action_settings,
                    R.drawable.collections_cloud
            };

            // Get the drawer layout from the XML file and the ListView inside it
            drawerLayout = (DrawerLayout)findViewById(R.id.drawer_layout);
            drawerList = (ListView)findViewById(R.id.listview_drawer);

            // Set a custom shadow over that overlays the main content
            // when the drawer opens
            drawerLayout.setDrawerShadow(
                    R.drawable.drawer_shadow, GravityCompat.START);

            // Pass the string arrays to the MenuListAdapter, set the drawer
            // list adapter to it and set up its click listener
            menuAdapter = new MenuListAdapter(
                    MainActivity.this, titles, subtitles, icons);
            drawerList.setAdapter(menuAdapter);
            drawerList.setOnItemClickListener(new DrawerItemClickListener());

            // Enable the action bar to have up navigation
            getSupportActionBar().setHomeButtonEnabled(true);
            getSupportActionBar().setDisplayHomeAsUpEnabled(true);

            // Allow the the action bar to toggle the drawer
            drawerToggle = new ActionBarDrawerToggle(
                    this,
                    drawerLayout,
                    R.drawable.ic_drawer,
                    R.string.drawer_open,
                    R.string.drawer_close){

                public void onDrawerClosed(View view){
                    super.onDrawerClosed(view);
                }
                public void onDrawerOpened(View view){
                    getSupportActionBar().setTitle(drawerTitle);
                    super.onDrawerOpened(view);
                }
            };
            drawerLayout.setDrawerListener(drawerToggle);

            // If this is the first time opening this activity,
            // start with loading fragment #1
            if (savedInstanceState == null){
                selectItem(0);
            }       

        }

        // Methods ----------------------------------------------------------------
        @Override
        public boolean onOptionsItemSelected(MenuItem item){

            // If the user has pressed the action bar icon
            if (item.getItemId() == android.R.id.home){

                // If the drawer is open, close it; vice versa
                if (drawerLayout.isDrawerOpen(drawerList)){
                    drawerLayout.closeDrawer(drawerList);
                } else {
                    drawerLayout.openDrawer(drawerList);
                }
            }

            // Finish by letting the super class do the rest
            return super.onOptionsItemSelected(item);

        }
        @Override
        protected void onPostCreate(Bundle savedInstanceState){

            // Call the super implementation and synchronize the drawer
            super.onPostCreate(savedInstanceState);
            drawerToggle.syncState();

        }
        @Override
        public void onConfigurationChanged(Configuration newConfig){

            // Call the super implemenation on this activity
            // and the drawer toggle object
            super.onConfigurationChanged(newConfig);
            drawerToggle.onConfigurationChanged(newConfig);

        }
        private void selectItem(int position){

            // Create a new fragment transaction and start it
            FragmentTransaction fragTran = getSupportFragmentManager()
                                           .beginTransaction();

            // Locate the position selected replace the content view
            // with the fragment of the number selected
            switch (position){
                case 0:{
                    fragTran.replace(R.id.content_frame, fragment1);
                    break;
                }
                case 1:{
                    fragTran.replace(R.id.content_frame, fragment2);
                    break;
                }
                case 2:{
                    fragTran.replace(R.id.content_frame, fragment3);
                    break;
                }
            }

            // Commit the transaction and close the drawer
            fragTran.commit();
            drawerList.setItemChecked(position, true);
            drawerLayout.closeDrawer(drawerList);

        }
        public void setTitle(CharSequence title){

            // Save the passed in title and set the action bar title
            this.title = title;
            getSupportActionBar().setTitle(title);

        }

        // Classes ----------------------------------------------------------------
        private class DrawerItemClickListener 
        implements ListView.OnItemClickListener{

            @Override
            public void onItemClick(
                    AdapterView<?> parent, 
                    View view, 
                    int position,
                    long id) {

                // When clicked, select open the appropriate fragment
                selectItem(position);

            }

        }

    }

以及崩溃日志:

09-26 16:45:43.081: D/AndroidRuntime(1121): Shutting down VM
09-26 16:45:43.081: W/dalvikvm(1121): threadid=1: thread exiting with uncaught exception (group=0x409961f8)
09-26 16:45:45.561: E/AndroidRuntime(1121): FATAL EXCEPTION: main
09-26 16:45:45.561: E/AndroidRuntime(1121): java.lang.NullPointerException
09-26 16:45:45.561: E/AndroidRuntime(1121):     at com.example.sidemenututorial.MenuListAdapter.getView(MenuListAdapter.java:73)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.widget.AbsListView.obtainView(AbsListView.java:2033)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.widget.ListView.makeAndAddView(ListView.java:1772)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.widget.ListView.fillDown(ListView.java:672)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.widget.ListView.fillFromTop(ListView.java:732)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.widget.ListView.layoutChildren(ListView.java:1625)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.widget.AbsListView.onLayout(AbsListView.java:1863)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.view.View.layout(View.java:11180)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.view.ViewGroup.layout(ViewGroup.java:4203)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:672)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.view.View.layout(View.java:11180)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.view.ViewGroup.layout(ViewGroup.java:4203)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.widget.FrameLayout.onLayout(FrameLayout.java:431)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.view.View.layout(View.java:11180)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.view.ViewGroup.layout(ViewGroup.java:4203)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1628)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1486)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.widget.LinearLayout.onLayout(LinearLayout.java:1399)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.view.View.layout(View.java:11180)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.view.ViewGroup.layout(ViewGroup.java:4203)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.widget.FrameLayout.onLayout(FrameLayout.java:431)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.view.View.layout(View.java:11180)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.view.ViewGroup.layout(ViewGroup.java:4203)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1468)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2418)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.os.Handler.dispatchMessage(Handler.java:99)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.os.Looper.loop(Looper.java:137)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at android.app.ActivityThread.main(ActivityThread.java:4340)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at java.lang.reflect.Method.invokeNative(Native Method)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at java.lang.reflect.Method.invoke(Method.java:511)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
09-26 16:45:45.561: E/AndroidRuntime(1121):     at dalvik.system.NativeStart.main(Native Method)
09-26 16:45:45.593: D/dalvikvm(1121): GC_CONCURRENT freed 191K, 3% free 14296K/14599K, paused 12ms+8ms

Answer 1

当你得到 Error inflating your class 时，你必须首先在你的 XML 中寻找问题。

在您的情况下，问题出在您的 drawer_list_item 布局中。在您的 linearLayout 根目录中，“?”字符导致 android:background="?android:color/darker_gray" 行。