android - 自定义 ListView 适配器 [Mono Android] 中的 OutOfMemory 错误

Question

你好 Stack Overflow Android 用户，

请帮忙解答以下问题:

问题

我正在为一个列出鱼类种类的应用程序编写一个功能。我正在为适配器使用自定义的 ListView 适配器类(我们称其为 FishSpeciesListAdapter)。目前，我有 27 种鱼类被记录为程序的默认值(您最终也可以自己添加一些)。问题是，当我将适配器链接到实际的 listview xml 对象并向下滚动列表时，过了一会儿，我收到以下错误:

UNHANDLED EXCEPTION: Java.Lang.OutOfMemoryError: Exception of type 'Java.Lang.OutOfMemoryError' was thrown.
at Android.Runtime.JNIEnv.CallStaticObjectMethod (intptr,intptr,Android.Runtime.JValue[]) <0x00080>
at Android.Graphics.BitmapFactory.DecodeByteArray (byte[],int,int) <0x001db>
at FishinTales.FishSpeciesListAdapter.GetView (int,Android.Views.View,Android.Views.ViewGroup) <0x002f7>
at Android.Widget.BaseAdapter.n_GetView_ILandroid_view_View_Landroid_view_ViewGroup_ (intptr,intptr,int,intptr,intptr) <0x00093>
at (wrapper dynamic-method) object.5dcc133f-a229-41c4-80e2-f5f5260ecdad (intptr,intptr,int,intptr,intptr) <0x0004b>

  --- End of managed exception stack trace ---
java.lang.OutOfMemoryError: bitmap size exceeds VM budget
    at android.graphics.BitmapFactory.nativeDecodeByteArray(Native Method)
    at android.graphics.BitmapFactory.decodeByteArray(BitmapFactory.java:392)
    at android.graphics.BitmapFactory.decodeByteArray(BitmapFactory.java:405)
    at fishintales.FishSpeciesListAdapter.n_getView(Native Method)
    at fishintales.FishSpeciesListAdapter.getView(FishSpeciesListAdapter.java:55)
    at android.widget.AbsListView.obtainView(AbsListView.java:1294)
    at android.widget.ListView.addViewBelow(ListView.java:2896)
    at android.widget.ListView.scrollListItemsBy(ListView.java:2825)
    at android.widget.ListView.arrowScrollImpl(ListView.java:2322)
    at android.widget.ListView.arrowScroll(ListView.java:2269)
    at android.widget.ListView.commonKey(ListView.java:2071)
    at android.widget.ListView.onKeyDown(ListView.java:2018)
    at android.view.KeyEvent.dispatch(KeyEvent.java:1037)
    at android.view.View.dispatchKeyEvent(View.java:3740)
    at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:786)
    at android.widget.ListView.dispatchKeyEvent(ListView.java:2003)
    at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:788)
    at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:788)
    at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:788)
    at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:788)
    at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchKeyEvent(PhoneWindow.java:1667)
    at com.android.internal.policy.impl.PhoneWindow.superDispatchKeyEvent(PhoneWindow.java:1102)
    at android.app.Activity.dispatchKeyEvent(Activity.java:2063)
    at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1643)
    at android.view.ViewRoot.deliverKeyEventToViewHierarchy(ViewRoot.java:2471)
    at android.view.ViewRoot.handleFinishedEvent(ViewRoot.java:2441)
    at android.view.ViewRoot.handleMessage(ViewRoot.java:1735)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:123)
    at android.app.ActivityThread.main(ActivityThread.java:4627)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:521)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
    at dalvik.system.NativeStart.main(Native Method)

Unhandled Exception:
Java.Lang.OutOfMemoryError: Exception of type 'Java.Lang.OutOfMemoryError' was thrown.
at Android.Runtime.JNIEnv.CallStaticObjectMethod (intptr,intptr,Android.Runtime.JValue[]) <0x00080>
at Android.Graphics.BitmapFactory.DecodeByteArray (byte[],int,int) <0x001db>
at FishinTales.FishSpeciesListAdapter.GetView (int,Android.Views.View,Android.Views.ViewGroup) <0x002f7>
at Android.Widget.BaseAdapter.n_GetView_ILandroid_view_View_Landroid_view_ViewGroup_ (intptr,intptr,int,intptr,intptr) <0x00093>
at (wrapper dynamic-method) object.5dcc133f-a229-41c4-80e2-f5f5260ecdad (intptr,intptr,int,intptr,intptr) <0x0004b>

  --- End of managed exception stack trace ---
java.lang.OutOfMemoryError: bitmap size exceeds VM budget
    at android.graphics.BitmapFactory.nativeDecodeByteArray(Native Method)
    at android.graphics.BitmapFactory.decodeByteArray(BitmapFactory.java:392)
    at android.graphics.BitmapFactory.decodeByteArray(BitmapFactory.java:405)
    at fishintales.FishSpeciesListAdapter.n_getView(Native Met

这是我的自定义 ListAdapter:

public class FishSpeciesListAdapter : BaseAdapter
{
    Context n_context;
    List<AppCode.Specie> n_specieData;

    public FishSpeciesListAdapter (Context context, List<AppCode.Specie> specieData)
    {
        this.n_context = context;
        this.n_specieData = specieData;
    }

    public override int Count {
        get { return this.n_specieData.Count; }
    }

    public override Java.Lang.Object GetItem (int position)
    {
        return null;
    }

    public override long GetItemId (int position)
    {
        return 0;
    }

    // create a new ImageView for each item referenced by the Adapter
    public override View GetView (int position, View convertView, ViewGroup parent)
    {
        View v;
        if(convertView==null){

            LayoutInflater li = LayoutInflater.FromContext(parent.Context);
            v = li.Inflate(Resource.Layout.Adapter_FishSpeciesIcon, null);
        }
        else
        {
            v = convertView;
        }
        ImageView iconImage = (ImageView)convertView.FindViewById(Resource.Id.xml_adapter_fishSpeciesIconImage);
        TextView nameText = (TextView)convertView.FindViewById(Resource.Id.xml_adapter_fishSpeciesNameText);
        TextView scientificNameText = (TextView)convertView.FindViewById(Resource.Id.xml_adapter_fishSpeciesScientificNameText);

        nameText.Text = this.n_specieData[position].Name;
        scientificNameText.Text = this.n_specieData[position].ScientificName;

        if (this.n_specieData[position].RelatedMedia.AttachedPhotos.Count < 1)
        {
            iconImage.SetImageResource(Resource.Drawable.Icon); 
        }
        else
        {
            iconImage.SetImageBitmap(BitmapFactory.DecodeByteArray(this.n_specieData[position].RelatedMedia.AttachedPhotos[0], 0, this.n_specieData[position].RelatedMedia.AttachedPhotos[0].Length));  
        }   

        return v;
    }
}

代表我进行的其他研究

所有图像都在 100-300KB 范围内。这真的会导致这个问题吗？

请reference my last post对于其他代码，因为它有点相关但需要一个新问题。感谢您的宝贵时间和帮助。

Answer 1

解决了!

它所做的是在每次调用 GetView 时都无法将字节数组解码为位图。所以我所做的是在构造函数中将它们全部转换并制作一个位图缓存以在调用 GetView 方法时引用。

这是我更新后的自定义 ListView 适配器。

public class FishSpeciesListAdapter : BaseAdapter
{
    Context n_context;
    List<AppCode.Specie> n_specieData;
    List<Bitmap> n_bitmapCache;

    public FishSpeciesListAdapter (Context context, List<AppCode.Specie> specieData)
    {
        this.n_context = context;
        this.n_specieData = specieData;
        this.n_bitmapCache = new List<Bitmap>();
        this.LoadBitmapsIntoCache();
    }

    private void LoadBitmapsIntoCache()
    {
        foreach(AppCode.Specie specie in this.n_specieData)
        {
            if (specie.RelatedMedia.AttachedPhotos.Count < 1)
            {
                this.n_bitmapCache.Add(BitmapFactory.DecodeResource(this.n_context.Resources, Resource.Drawable.Icon)); 
            }
            else
            {
                this.n_bitmapCache.Add(BitmapFactory.DecodeByteArray(specie.RelatedMedia.AttachedPhotos[0], 0, specie.RelatedMedia.AttachedPhotos[0].Length));  
            }
        }
    }

    public override int Count {
        get { return this.n_specieData.Count; }
    }

    public override Java.Lang.Object GetItem (int position)
    {
        return null;
    }

    public override long GetItemId (int position)
    {
        return 0;
    }

    // create a new ImageView for each item referenced by the Adapter
    public override View GetView (int position, View convertView, ViewGroup parent)
    {
        if(convertView==null){

            LayoutInflater li = LayoutInflater.FromContext(parent.Context);
            convertView = li.Inflate(Resource.Layout.Adapter_FishSpeciesIcon, null);
        }

        ImageView iconImage = (ImageView)convertView.FindViewById(Resource.Id.xml_adapter_fishSpeciesIconImage);
        TextView nameText = (TextView)convertView.FindViewById(Resource.Id.xml_adapter_fishSpeciesNameText);
        TextView scientificNameText = (TextView)convertView.FindViewById(Resource.Id.xml_adapter_fishSpeciesScientificNameText);

        nameText.Text = this.n_specieData[position].Name;
        scientificNameText.Text = this.n_specieData[position].ScientificName;
        iconImage.SetImageBitmap(this.n_bitmapCache[position]); 

        return convertView;
    }
}

在构造函数中调用 LoadBitmapsIntoCache() 并将位图保存到列表后。问题已解决，我可以滚动浏览所有鱼类，而不会出现任何 OutOfMemory 错误。感谢所有提供帮助的人。