如何制作可变的可绘制对象数组？

Question

我必须使用什么类型的列表才能将 ImageView 的背景设置为可变可绘制对象？

例如：有 6 个可绘制对象：image1、image2、image3、image4、image5、image6 如果您选择 image1 和 image4，我需要这两个图像的列表。

我需要从该列表中随机将 ImageView 设置为其中一张图片。

这怎么可能？

Answer 1

这里也许有帮助

layouts = new int[]{
            R.drawable.welcome_slide1,
            R.drawable.welcome_slide2,
            R.drawable.welcome_slide3,
            R.drawable.welcome_slide4};

更准确

ArrayList<Integer> myImageList = new ArrayList<>();
myImageList.add(R.drawable.thingOne);
myImageList.add(R.drawable.thingtwo);
myImageList.add(R.drawable.thingthree);

myImageView.setImageResource(myImageList.get(i));

Answer 2

您首先需要创建一个选择列表，然后创建一个按钮，单击该按钮仅选择所选项目的列表，然后从所选项目列表中设置随机图像。

所以对于布局：主要布局：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">
    <androidx.recyclerview.widget.RecyclerView
        android:layout_width="match_parent"
        android:layout_height="200dp"
      android:id="@+id/selection_list"/>

  <Button
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
    android:id="@+id/get_selection"
    android:text="Show randomly selected"/>
  <ImageView
      android:layout_width="300dp"
      android:layout_height="300dp"
    android:id="@+id/random_img"/>




</LinearLayout>

然后选择列表的适配器：

public class test_adapter extends  RecyclerView.Adapter<test_adapter.view> {

    Context cntxt;
    public ArrayList<selection_items> selection_items_list;
    AdapterView.OnItemClickListener listener;
  public test_adapter(Context cntxt, ArrayList<selection_items> selection_items_list)
    {
        this.cntxt=cntxt;
        this.selection_items_list = selection_items_list;


    }

    public ArrayList<selection_items> selected_items()
    {
        ArrayList<selection_items> selected_=new ArrayList<>();
        for(int i = 0; i< selection_items_list.size(); i++)
        {
            if(selection_items_list.get(i).selected){
                selected_.add(selection_items_list.get(i));
            }
        }
        return selected_;
    }

    @NonNull
    @Override
    public view onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(cntxt).inflate(R.layout.img_in_list_test, parent, false);

        return new view(view);
    }

    @Override
    public void onBindViewHolder(@NonNull view holder, int position) {
      selection_items obj= selection_items_list.get(position);

      holder.name.setText(obj.name);
      holder.img.setImageDrawable(cntxt.getDrawable(obj.img));

holder.name.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
    @Override
    public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
        obj.selected=b;
    }
});



    }


    @Override
    public int getItemCount() {
        return selection_items_list.size();
    }

    public class view extends RecyclerView.ViewHolder implements View.OnClickListener {
      public CheckBox name;
      public ImageView img;



      public void  set_printed()
      {
         itemView.setBackgroundColor(cntxt.getColor(R.color.primary_semi_transparent));
      }

        view(View itemView) {
            super(itemView);

            name = itemView.findViewById(R.id.check);
            img = itemView.findViewById(R.id.img);





        }

        @Override
        public void onClick(View view) {

 }
    }
}

您选择的项目布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal" android:layout_width="match_parent"

    android:layout_height="52dp">
<ImageView
    android:layout_width="50dp"
    android:id="@+id/img"
    android:layout_height="50dp"
    />
    <CheckBox
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/check"/>
</LinearLayout>

终于是你的activity

public class TestActivity extends AppCompatActivity {

    RecyclerView selection_view;
    Button get_selection;
    ImageView random_selected;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_test);
        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        selection_view = findViewById(R.id.selection_list);
        get_selection = findViewById(R.id.get_selection);
        random_selected = findViewById(R.id.random_img);


        selection_view.setLayoutManager(new LinearLayoutManager(this));
    
        ArrayList<selection_items> selection_items=new ArrayList<>();

        selection_items.add(new selection_items("Image 1",R.drawable.backup_icon));
        selection_items.add(new selection_items("Image 2",R.drawable.ic_add_photo));
        selection_items.add(new selection_items("Image 3",R.drawable.ic_barcode_scan));

        selection_view.setAdapter(new test_adapter(this,selection_items));

        get_selection.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                ArrayList<selection_items> selected_items=((test_adapter)selection_view.getAdapter()).selected_items();
                if(selected_items.size()>0){
                    random_selected.setImageDrawable(getDrawable(selected_items.get(new Random().nextInt(selected_items.size())).img));
                }else{
                    random_selected.setImageDrawable(null);

                }
            }
        });




    }
}

如何制作可变的可绘制对象数组？

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