Question

我想设置两个活动，每个活动具有一个listview。为此，我已经为其设计设计了自己的xml文件，因此listview具有不同的textview和图像。但是我想在两个列表视图上使用相同的适配器。

那是我的carnes活动的java文件。

public class Carnes extends AppCompatActivity {
    private ListView lvItems;
    private Adapter adaptador;

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

        lvItems = (ListView) findViewById(R.id.lv_carnes);
        adaptador = (Adapter) new Adaptador(this, GetArrayItems());
        lvItems.setAdapter((ListAdapter) adaptador);
    }

    private ArrayList<Entidad> GetArrayItems() {
        ArrayList<Entidad> listItems = new ArrayList<>();
        listItems.add(new Entidad(R.drawable.calabacines_3, "Lomo", " 5 min.", 5, R.drawable.color_carnes));
        listItems.add(new Entidad(R.drawable.patatas_deluxe_especiadas_70523_300_150, "Pollo", " 20 min.", 4, R.drawable.color_carnes));
        listItems.add(new Entidad(R.drawable.tomate, "Pavo", " 1 min.", 3, R.drawable.color_carnes));

        return listItems;
    }
}

这是我的适配器：

public class Adaptador extends BaseAdapter {
    private Context context;
    private ArrayList<Entidad> listItems;

    public Adaptador(Context context, ArrayList<Entidad> listItems) {
        this.context = context;
        this.listItems = listItems;
    }

    @Override
    public int getCount() {
        return listItems.size();
    }

    @Override
    public Object getItem(int position) {
        return listItems.get(position);
    }

    @Override
    public long getItemId(int position) {
        return 0;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        Entidad Item = (Entidad) getItem(position);

        convertView = LayoutInflater.from(context).inflate(R.layout.elemento_lista, null);
        ImageView imgFoto = (ImageView) convertView.findViewById(R.id.imgFoto);
        TextView tvTitulo = (TextView) convertView.findViewById(R.id.tvTitulo);
        TextView tvTiempo = (TextView) convertView.findViewById(R.id.tvTiempo);
        RatingBar calificacion = (RatingBar) convertView.findViewById(R.id.ratingBarVerd);
        ImageView colorfondo = (ImageView) convertView.findViewById(R.id.colorfondo);


        imgFoto.setImageResource(Item.getImgFoto());
        tvTitulo.setText(Item.getTitulo());
        tvTiempo.setText(Item.getTiempo());
        calificacion.setRating(Item.getRating());
        colorfondo.setImageResource(Item.getColorfondo());

        return convertView;
    }
}

我将下面使用相同适配器的其他活动留给您（记住这是一个不同的列表视图）：

public class Verduras extends AppCompatActivity {
    private ListView lvItems;
    private Adapter adaptador;

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

        lvItems = (ListView) findViewById(R.id.lv_verduras);
        adaptador = (Adapter) new Adaptador(this, GetArrayItems());
        lvItems.setAdapter((ListAdapter) adaptador);
    }

    private ArrayList<Entidad> GetArrayItems() {
        ArrayList<Entidad> listItems = new ArrayList<>();
        listItems.add(new Entidad(R.drawable.calabacines_3, "Calabacines", " 10 min.", 4, R.drawable.color_verduras));
        listItems.add(new Entidad(R.drawable.patatas_deluxe_especiadas_70523_300_150, "Patatas", " 15 min.", 2, R.drawable.color_verduras));
        listItems.add(new Entidad(R.drawable.tomate, "Tomates", " 2 min.", 5, R.drawable.color_verduras));

        return listItems;
    }
}

这就是我用来定义变量的内容：

public class Entidad {

    private int imgFoto;
    private String titulo;
    private String tiempo;
    private int ratingBar;
    private int colorfondo;

    public Entidad(int imgFoto, String titulo, String tiempo, int ratingBar, int colorfondo) {

        this.imgFoto = imgFoto;
        this.titulo = titulo;
        this.tiempo = tiempo;
        this.ratingBar = ratingBar;
        this.colorfondo = colorfondo;
    }

    public int getImgFoto() {
        return imgFoto;
    }

    public String getTitulo() {
        return titulo;
    }

    public String getTiempo() {
        return tiempo;
    }

    public int getRating() { return ratingBar; }

    public int getColorfondo() {
        return colorfondo;
    }
}

发生的事情是该代码看起来还可以，但是当您运行该应用程序时，它突然停止了，而没有告诉您发生了什么事情。

感谢您的帮助，如果您需要其他任何帮助，请告诉我。

这就是logcat上显示的内容。

05-29 16:08:38.173 2247-2247/com.test.platos4 E/AndroidRuntime: FATAL EXCEPTION: main
    android.content.res.Resources$NotFoundException: Resource ID #0x7f060059
        at android.content.res.Resources.getValue(Resources.java:1013)
        at android.support.v7.widget.ResourcesWrapper.getValue(ResourcesWrapper.java:209)
        at android.support.v7.widget.AppCompatDrawableManager.loadDrawableFromDelegates(AppCompatDrawableManager.java:331)
        at android.support.v7.widget.AppCompatDrawableManager.getDrawable(AppCompatDrawableManager.java:198)
        at android.support.v7.widget.AppCompatDrawableManager.getDrawable(AppCompatDrawableManager.java:191)
        at android.support.v7.content.res.AppCompatResources.getDrawable(AppCompatResources.java:102)
        at android.support.v7.widget.AppCompatImageHelper.setImageResource(AppCompatImageHelper.java:86)
        at android.support.v7.widget.AppCompatImageView.setImageResource(AppCompatImageView.java:94)
        at com.test.platos4.Adaptador.getView(Adaptador.java:62)
        at android.widget.AbsListView.obtainView(AbsListView.java:2271)
        at android.widget.ListView.makeAndAddView(ListView.java:1769)
        at android.widget.ListView.fillDown(ListView.java:672)
        at android.widget.ListView.fillFromTop(ListView.java:733)
        at android.widget.ListView.layoutChildren(ListView.java:1622)
        at android.widget.AbsListView.onLayout(AbsListView.java:2106)
        at android.view.View.layout(View.java:13754)
        at android.view.ViewGroup.layout(ViewGroup.java:4364)
        at android.widget.RelativeLayout.onLayout(RelativeLayout.java:948)
        at android.view.View.layout(View.java:13754)
        at android.view.ViewGroup.layout(ViewGroup.java:4364)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
        at android.view.View.layout(View.java:13754)
        at android.view.ViewGroup.layout(ViewGroup.java:4364)
        at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1649)
        at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1507)
        at android.widget.LinearLayout.onLayout(LinearLayout.java:1420)
        at android.view.View.layout(View.java:13754)
        at android.view.ViewGroup.layout(ViewGroup.java:4364)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
        at android.view.View.layout(View.java:13754)
        at android.view.ViewGroup.layout(ViewGroup.java:4364)
        at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1649)
        at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1507)
        at android.widget.LinearLayout.onLayout(LinearLayout.java:1420)
        at android.view.View.layout(View.java:13754)
        at android.view.ViewGroup.layout(ViewGroup.java:4364)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
        at android.view.View.layout(View.java:13754)
        at android.view.ViewGroup.layout(ViewGroup.java:4364)
        at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:1868)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1689)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1000)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4214)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
        at android.view.Choreographer.doCallbacks(Choreographer.java:555)
        at android.view.Choreographer.doFrame(Choreographer.java:525)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
        at android.os.Handler.handleCallback(Handler.java:615)
        at android.os.Handler.dispatchMessage(Handler.java:92)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:4745)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
        at dalvik.system.NativeStart.main(Native Method)
05-29 16:08:38.183 1379-1571/system_process W/ActivityManager:   Force finishing activity com.test.platos4/.Carnes
05-29 16:08:38.323 1379-1571/system_process D/dalvikvm: GC_FOR_ALLOC freed 658K, 12% free 22447K/25415K, paused 19ms, total 19ms
05-29 16:08:38.323 1379-1571/system_process W/ActivityManager:   Force finishing activity com.test.platos4/.Dishes
05-29 16:08:38.413 1121-1621/? D/gralloc_ranchu: gralloc_alloc: Creating ashmem region of size 1114112
05-29 16:08:38.853 1379-1392/system_process W/ActivityManager: Activity pause timeout for ActivityRecord{a78e7c78 com.test.platos4/.Carnes}
05-29 16:08:39.403 1121-1456/? D/gralloc_ranchu: gralloc_alloc: Creating ashmem region of size 1114112
05-29 16:08:39.663 1121-1456/? D/gralloc_ranchu: gralloc_alloc: Creating ashmem region of size 1114112
05-29 16:08:48.043 1379-1392/system_process W/ActivityManager: Launch timeout has expired, giving up wake lock!
    Activity idle timeout for ActivityRecord{a78e7c78 com.test.platos4/.Carnes}
05-29 16:08:48.863 1379-1392/system_process W/ActivityManager: Activity idle timeout for ActivityRecord{a7ce95d0 com.test.platos4/.Menu}
05-29 16:08:58.043 1379-1392/system_process W/ActivityManager: Activity destroy timeout for ActivityRecord{a7ce7888 com.test.platos4/.Dishes}
    Activity destroy timeout for ActivityRecord{a78e7c78 com.test.platos4/.Carnes}
05-29 16:09:00.013 1440-1440/com.android.systemui D/EGL_emulation: eglMakeCurrent: 0xb8af20d0: ver 2 0

Answer 1

在您的代码中，如果您未使用相同的适配器，您将在两个Activities中实例化一个新适配器，例如：new Adaptador(...)

这里是tutorial，关于将BaseAdapter与ListView一起使用

以下是本教程的摘要，显示了getView()应该如何工作：

@Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // inflate the layout for each list row
        if (convertView == null) {
            convertView = LayoutInflater.from(context).
                inflate(R.layout.layout_list_view_row_items, parent, false);
        }

        // get current item to be displayed
        Item currentItem = (Item) getItem(position);

        // get the TextView for item name and item description
        TextView textViewItemName = (TextView) 
            convertView.findViewById(R.id.text_view_item_name);
        TextView textViewItemDescription = (TextView) 
            convertView.findViewById(R.id.text_view_item_description);

        //sets the text for item name and item description from the current item object
        textViewItemName.setText(currentItem.getItemName());
        textViewItemDescription.setText(currentItem.getItemDescription());

        // returns the view for the current row
        return convertView;
    }
}

要优化列表视图的性能，应使用新的行布局仅当convertView == null时才膨胀。这是因为适配器的每当listview需要显示新行时，都会调用getView方法屏幕上。 convertView在此过程中被回收。因此，当convertView == null时，行布局应该只膨胀一次，并且它的内容应该在随后的getView调用中更新每次通话增加新行的成本很高。

我也建议使用RecyclerView insted of ListView。创建RecyclerView是为了解决ListView曾经/曾经存在的许多问题。

我可以在不同的活动中将相同的适配器用于两个不同的列表视图吗？

1 个答案: