如何让RecyclerView的每一项启动一个唯一的Activity？

Question

我正在开发一个食谱应用程序。我想要做到这一点，以便单击“早餐主菜”进入“早餐主菜活动”，单击“甜点”进入“甜点活动”，单击“饮料”进入“饮料活动”，等等。现在，单击任何食谱类别都会将我带到“早餐主菜活动”。

我在下面包含了 RecipeCategories 类以及 RecipeCategoriesAdapter 类。

package app.android.easyvegan;

import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import java.util.Arrays;
import java.util.List;
import java.util.Objects;
import android.view.Menu;
import android.view.MenuItem;

public class RecipeCategories extends AppCompatActivity implements RecipeCategoriesSelectionListener {

    public void onCreate(Bundle savedInstanceState) {
        Utilities.SetTheme(getSharedPreferences("Themes", 0).getInt("theme", 0));
        Utilities.onActivityCreateSetTheme(this);
        super.onCreate(savedInstanceState);
        setContentView(R.layout.recipe_categories);
        setSupportActionBar(findViewById(R.id.topToolbar));
        Objects.requireNonNull(getSupportActionBar()).setDisplayHomeAsUpEnabled(true);
        RecyclerView recyclerView = findViewById(R.id.recipeCategoriesRecycler);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setHasFixedSize(true);

        List<String> recipeCategoriesList = Arrays.asList(getResources().getStringArray(R.array.recipe_categories));
        RecipeCategoriesAdapter adapter = new RecipeCategoriesAdapter(recipeCategoriesList, this);
        recyclerView.setAdapter(adapter);

    }

        public boolean onCreateOptionsMenu (Menu menu){
            getMenuInflater().inflate(R.menu.menu_recipe_categories, menu);
            return true;
        }

        public boolean onOptionsItemSelected (MenuItem item){
            SharedPreferences.Editor editor = getSharedPreferences("Themes", 0).edit();

            switch (item.getItemId()) {
                case 2131296477:
                    startActivity(new Intent(this, HomeScreen.class));
                    break;
                case 2131296666:
                    Intent intent = new Intent("android.intent.action.SEND");
                    intent.setType("text/plain");
                    intent.putExtra("android.intent.extra.SUBJECT", "EasyVegan Recipes");
                    intent.putExtra("android.intent.extra.TEXT", "EasyVegan: Plant-Based Recipes App");
                    startActivity(Intent.createChooser(intent, "Share using"));
                    break;
                case 2131296782:
                    Utilities.changeToTheme(this, 0);
                    editor.putInt("theme", 0);
                    editor.apply();
                    break;
                case 2131296780:
                    Utilities.changeToTheme(this, 1);
                    editor.putInt("theme", 1);
                    editor.apply();
                    break;
            }
            return super.onOptionsItemSelected(item);
        }

    @Override
    public void onRecipeCategorySelected(String recipeCategory)
    {
        Intent intent = new Intent(this, BreakfastEntrees.class);
        startActivity(intent);

    }
}


__________________________________________________________________________________

package app.android.easyvegan;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.ViewGroup;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import java.util.List;

public class RecipeCategoriesAdapter extends RecyclerView.Adapter<RecipeCategoriesAdapter.RecipeCategoriesViewHolder> {

    private final List<String> recipeCategoriesList;
    private final RecipeCategoriesSelectionListener selectionListener;

    public RecipeCategoriesAdapter(List<String> recipeCategoriesList, Context context) {
        this.recipeCategoriesList = recipeCategoriesList;
        selectionListener = (RecipeCategories) context;
    }

    @NonNull
    @Override
    public RecipeCategoriesViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType)
    {
        TextView textView = (TextView) LayoutInflater.from(parent.getContext()).inflate(R.layout.recipe_categories_recycler,parent,false);
        return new RecipeCategoriesViewHolder(textView);
    }

    @Override
    public void onBindViewHolder(@NonNull RecipeCategoriesViewHolder holder, int position) {
        String recipeCategory = recipeCategoriesList.get(position);
        holder.recipeCategory.setText(recipeCategory);
        holder.recipeCategory.setOnClickListener(view -> selectionListener.onRecipeCategorySelected(recipeCategoriesList.get(holder.getAdapterPosition())));
    }

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

    public static class RecipeCategoriesViewHolder extends RecyclerView.ViewHolder
    {
        public TextView recipeCategory;
        public RecipeCategoriesViewHolder (@NonNull TextView itemView) {
            super(itemView);
            recipeCategory = itemView;

        }
    }
}

我尝试在每个位置的 onBindViewHolder 中添加“when”语句，但如果这是解决方案，我不知道如何正确编码。

我知道在 OnRecipeCategorySelected 中我已将其编码为仅启动 BreakfastEntreesActivity。我只是不确定如何调整它来为每个食谱类别启动不同的活动。

Answer 1

在 BindViewHolder 中，您必须设置 onClickListener 来启动与单击的项目相关的新活动。

如果您使用列表来显示 recyclerView 中的项目，这是我的应用程序适配器中的代码，它工作得很好。

public class RecipeViewHolder extends RecyclerView.ViewHolder {
    ImageView recipeImageView;
    TextView recipeNameTextView;
    TextView recipeTimeTextView;
    ConstraintLayout recipeItem;

    public RecipeViewHolder(View itemView) {
        super(itemView);
        recipeImageView = itemView.findViewById(R.id.recipeImageView1);
        recipeNameTextView = itemView.findViewById(R.id.recipeNameTextView1);
        recipeTimeTextView = itemView.findViewById(R.id.recipeTimeTextView1);
        recipeItem = itemView.findViewById(R.id.recipeItemSample);
    }
}

@Override
public RecipeViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View itemView = LayoutInflater.from(parent.getContext())
        .inflate(R.layout.item_recipe, parent, false);
    return new RecipeViewHolder(itemView);
}

@Override
public void onBindViewHolder(RecipeViewHolder holder, int position) {
    Recipe recipe = recipeList.get(position);
    holder.recipeNameTextView.setText(recipe.getName());
    holder.recipeTimeTextView.setText(recipe.getCookingTime());
    holder.recipeImageView.setImageResource(recipe.getImageUrl());

    holder.recipeItem.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            int selectedRecipeId = recipeList.get(position).getId();
            Intent intent = new Intent(fragment.requireContext(), RecipeDetailsActivity.class);
            intent.putExtra("recipe_id", selectedRecipeId);
            fragment.requireContext().startActivity(intent);
        }
    });
}

在我的例子中，该项目的父布局是约束布局。 另外，我在片段中使用 recyclerView。 如果您愿意，我可以分享适配器的完整代码。