如何使用意图将模型类型列表从适配器传递到另一个活动

Question

我有一个部门列表，其中包含部门名称，例如，男士，女士等。现在，如果我单击“女士”，则下一个屏幕应显示与该部门相关的类别列表女士们。 使用我当前的代码，仅显示类别列表中的第一项。这是我的部门适配器代码：

public class Department_Adapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
public static Context context;
private ArrayList<Department_model> arraylist;
private List<Department_model> models_list;


public Department_Adapter(Context context, List<Department_model> department_modelList) {
    this.models_list = department_modelList;
    this.arraylist = new ArrayList<Department_model>();
    this.arraylist.addAll(department_modelList);
    this.context = context;
}


public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
    View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.departments_childview, viewGroup, false);
    ViewHolder vh = new ViewHolder(v);
    return vh;
}

@Override
public void onBindViewHolder(@NonNull RecyclerView.ViewHolder viewHolder, final int i) {

    final ViewHolder myViewHolder = (ViewHolder)viewHolder;
    final Department_model model = models_list.get(i);
    myViewHolder.department_text.setText(model.getDepartment_Name());
    myViewHolder.relative_lay.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(context, Categories.class);
            String items[] = new String[models_list.size()];
            for(int j=0; j< items.length; j++) {
                intent.putExtra("category_name", models_list.get(i).Category_Name);
                intent.putExtra("category_id", models_list.get(i).Category_ID);
                intent.putExtra("subCatName", models_list.get(i).Sub_Cat_Name);
                intent.putExtra("subcatID", models_list.get(i).Sub_Cat_ID);
                intent.putExtra("Article_ID", models_list.get(i).Article_ID);
                intent.putExtra("Article_Number", models_list.get(i).Article_Number);
                intent.putExtra("ArticleWSP", models_list.get(i).ArticleWSP);

                intent.putExtra("department_name", models_list.get(i).Department_Name);
            }
            context.startActivity(intent);
        }
    });
}

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

public class ViewHolder extends RecyclerView.ViewHolder {
    TextView department_text;
    ImageView right_arrow;
    RelativeLayout relative_lay;

    public ViewHolder(@NonNull View itemView) {
        super(itemView);
        department_text = (TextView) itemView.findViewById(R.id.department_text);
        right_arrow = (ImageView) itemView.findViewById(R.id.right_arrow);
        relative_lay = (RelativeLayout) itemView.findViewById(R.id.relative_lay);
    }
}

}

这是我的类别课程：

public class Categories extends AppCompatActivity {
RecyclerView category_recyclerView;
TextView category_textview;
ImageView back_arrow;
static Context ctx;
private static List<Category_model> category_modelList;
private static List<String> list;
private Category_Adapter category_adapter;
String cat_name, cat_id, title, subCatName, subcatID, Article_ID, Article_Number, ArticleWSP;




@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_categories);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    ctx = Categories.this;


        Intent intent = getIntent();
    cat_name = intent.getStringExtra("category_name");
    cat_id = intent.getStringExtra("category_id");
    subCatName = intent.getStringExtra("subCatName");
    subcatID = intent.getStringExtra("subcatID");
    Article_ID = intent.getStringExtra("Article_ID");
    Article_Number = intent.getStringExtra("Article_Number");
    ArticleWSP = intent.getStringExtra("ArticleWSP");

        title = intent.getStringExtra("department_name");


    category_recyclerView = (RecyclerView) findViewById(R.id.category_recyclerView);
    category_textview = (TextView) findViewById(R.id.category_textview);
    back_arrow = (ImageView) findViewById(R.id.back_arrow);
    category_textview.setText(title);

    RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getApplicationContext());
    category_recyclerView.setLayoutManager(mLayoutManager);
    category_recyclerView.setItemAnimator(new DefaultItemAnimator());
    category_recyclerView.addItemDecoration(new DividerItemDecoration(Categories.this, DividerItemDecoration.VERTICAL));

    category_modelList = new ArrayList<>();





        Category_model obj1 = new Category_model();
        obj1.setCategory_Name(cat_name);
        obj1.setCategory_ID(cat_id);
        category_modelList.add(obj1);



        category_adapter = new Category_Adapter(Categories.this, category_modelList);
        category_recyclerView.setAdapter(category_adapter);



    back_arrow.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            finish();
        }
    });


}

}

单击“部门”列表的特定位置时如何传递所有“类别”列表项？

Answer 1

我可以在您的代码中看到逻辑问题。这是代码创建问题的一部分。

Intent intent = new Intent(context, Categories.class);
        String items[] = new String[models_list.size()];
        for(int j=0; j< items.length; j++) {
            intent.putExtra("category_name", models_list.get(i).Category_Name);
            intent.putExtra("category_id", models_list.get(i).Category_ID);
            intent.putExtra("subCatName", models_list.get(i).Sub_Cat_Name);
            intent.putExtra("subcatID", models_list.get(i).Sub_Cat_ID);
            intent.putExtra("Article_ID", models_list.get(i).Article_ID);
            intent.putExtra("Article_Number", models_list.get(i).Article_Number);
            intent.putExtra("ArticleWSP", models_list.get(i).ArticleWSP);

            intent.putExtra("department_name", models_list.get(i).Department_Name);
        }
        context.startActivity(intent);

在这里，您要初始化大小为model_list **的项字符串数组。这没有任何意义。您的到达人数应为**可用类别的大小，在这里绝对没有人知道 category 会持续多久 model_list可能有多少匹配类别。因此，简单数组不是一个好主意。您需要使用ArrayList。自定义模式的ArrayList。自定义模型将作为您的类别模式。就像下面提到的

List<CategoryModel> categoryList = new ArrayList();

在单击偶数时，您需要获取有关单击哪个位置项的位置。然后，您需要获取该位置的模型对象。获取模型后，您需要找到实际的类别。对于类别，您需要选择该类别的一个属性，例如“名称或ID” 。现在，这将是您的过滤点。现在过滤您的 model_list （如果这也是包含您的类别的列表。我可以看到它是“部门列表”。如果此部门列表也包含类别，那么您需要使用列表来过滤列表） 。要过滤，您需要使用以下代码。

    Intent intent = new Intent(context, Categories.class);
    List<CategoryModel> categoryList = new ArrayList<>();
    //you need to get position of clicked item and that is stored in variable 'i'
    Department_model selectedModel = model_list.get(i);
    //here you have option you can filter with or the id let's suppose you are filtering with name then
    // get name of category
    String filterTag = selectedModel.Category_Name;
    for(int j=0; j< model_list.size(); j++) {
        //you need make category model with getter and setter properties
        if (filterTag.equalsIgnoreCase(selectedModel.Category_Name)) {
            CategoryModel  currentCategory = new CategoryModel();
            currentCategory.set(Category_Name);
            currentCategory.set(Category_ID);
            currentCategory.set(Sub_Cat_Name);
            currentCategory.set(Sub_Cat_ID);
            currentCategory.set(Article_ID);
            currentCategory.set(Article_Number);
            currentCategory.set(ArticleWSP);
            currentCategory.set(Department_Name);

            //here you have mapped category stuff in category model now you need to add in the list
            categoryList.add(currentCategory);
        }

    }

    Log.e("list_size",categoryList.size() );

    //after loop, you need to pass "categoryList" to the next activity and then use the same categoryList
    //to new activity of category adapter and now you are done ... phewww
    //you can use below code to pass list via intent 
    Bundle args = new Bundle();
    args.putSerializable("ARRAYLIST",(Serializable)categoryList);
    intent.putExtra("BUNDLE",args);
    context.startActivity(intent);

在类别活动的onCreate（）方法中，使用以下代码

Intent intent = getIntent();
Bundle args = intent.getBundleExtra("BUNDLE");
List<CategoryModel> list = args.getSerializable("ARRAYLIST");

现在，您可以对列表进行任何操作了。

更新，在完成循环后，我正在检查列表大小。您需要检查尺寸，并让我知道