如何实现RecyclerView卡片点击后控制MainActivity的RelativeLayout显示与文本设置

我来帮你搞定这个需求，核心思路是通过接口回调把Adapter里的点击事件传递给MainActivity，这样就能在MainActivity里操作目标RelativeLayout和控件了，具体步骤如下：

第一步：给CardAdapter添加点击回调接口 #

我们需要在CardAdapter里定义一个回调接口，用来把点击的卡片数据传递给MainActivity。修改后的CardAdapter代码如下：

public class CardAdapter extends RecyclerView.Adapter<CardAdapter.CardViewHolder> {
    private List<CardModel> cardModels;
    private Context context;
    // 定义点击回调接口
    private OnCardClickListener onCardClickListener;

    // 新增接口定义
    public interface OnCardClickListener {
        void onCardClick(CardModel cardModel);
    }

    // 修改构造方法，传入回调接口
    public CardAdapter(Context context, List<CardModel> cardModels, OnCardClickListener listener) {
        this.cardModels = cardModels;
        this.context = context;
        this.onCardClickListener = listener;
    }

    @NonNull
    @Override
    public CardViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(context).inflate(R.layout.cardbank_row, parent, false);
        return new CardViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull CardViewHolder holder, final int position) {
        CardModel cardModel = cardModels.get(position);
        holder.bank.setText(cardModel.getBank());
        holder.cardname.setText(cardModel.getCardname());
        holder.cardnumber.setText(cardModel.getCardnumber());
        
        // 点击事件里调用回调方法，传递当前卡片数据
        holder.card.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (onCardClickListener != null) {
                    onCardClickListener.onCardClick(cardModel);
                }
            }
        });
    }

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

    public class CardViewHolder extends RecyclerView.ViewHolder {
        TextView bank, cardnumber, cardname;
        ImageView bicon;
        CardView card;
        public CardViewHolder(@NonNull View itemView) {
            super(itemView);
            card = itemView.findViewById(R.id.cardbank_row);
            bicon = itemView.findViewById(R.id.iv_row_banklogo);
            bank = itemView.findViewById(R.id.iv_row_bankname);
            cardnumber = itemView.findViewById(R.id.tv_row_cardnumber);
            cardname = itemView.findViewById(R.id.tv_row_cardname);
        }
    }
}

第二步：在MainActivity中实现回调并处理布局逻辑 #

接下来我们要在MainActivity里实现刚才定义的接口，处理点击后的显示和数据填充逻辑：

1. 让MainActivity实现CardAdapter.OnCardClickListener接口
2. 初始化Adapter时传入回调实例
3. 在回调方法中显示目标RelativeLayout，并填充对应的数据
4. 给close按钮添加点击事件，用来隐藏详情布局

修改后的MainActivity代码关键部分如下：

public class MainActivity extends AppCompatActivity implements CardAdapter.OnCardClickListener {
    RelativeLayout add, close, card;
    ImageView copy, share, notification;
    TextView cardbank, cardnumber, cardname;
    CoordinatorLayout coordinatorLayout;
    private static final int TIME_INTERVAL = 2000;
    private long mBackPressed;
    MyDatabase myDatabase;
    RecyclerView recyclerView;
    private List<CardModel> cardModelList;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        cast();
        // 初始化时隐藏详情布局
        card.setVisibility(View.GONE);
        dbcast();
        onClick();
    }

    public void cast(){
        add=findViewById(R.id.rv_btns_add);
        close=findViewById(R.id.rv_bank_close);
        copy=findViewById(R.id.iv_btn_copy);
        share=findViewById(R.id.iv_btn_share);
        notification=findViewById(R.id.iv_toolbar_notofication);
        coordinatorLayout=findViewById(R.id.mysnakbar);
        card=findViewById(R.id.rv_card_card);
        cardbank=findViewById(R.id.tv_bank_bankname);
        cardnumber=findViewById(R.id.tv_bnumber_cardnumber);
        cardname=findViewById(R.id.tv_name_cardname);
        cardModelList=new ArrayList<>();
        recyclerView=findViewById(R.id.rv_footer_list);
        recyclerView.setLayoutManager(new LinearLayoutManager(MainActivity.this,RecyclerView.VERTICAL,false));
    }

    public void dbcast(){
        myDatabase=new MyDatabase(getApplicationContext());
        Cursor cursor=myDatabase.getInfos();
        for(cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext()){
            CardModel cardModel=new CardModel();
            cardModel.setId(cursor.getInt(0));
            cardModel.setBank(cursor.getString(1));
            cardModel.setCardnumber(cursor.getString(2));
            cardModel.setCardname(cursor.getString(3));
            cardModelList.add(cardModel);
        }
        // 初始化Adapter时传入当前MainActivity作为回调实例
        recyclerView.setAdapter(new CardAdapter(MainActivity.this, cardModelList, this));
    }

    public void onClick(){
        // 给close按钮添加点击事件，隐藏详情布局
        close.setOnClickListener(v -> card.setVisibility(View.GONE));
        
        // 其他按钮的点击逻辑可以保留
        // ...
    }

    // 实现接口的回调方法
    @Override
    public void onCardClick(CardModel cardModel) {
        // 显示详情布局
        card.setVisibility(View.VISIBLE);
        // 填充对应的数据
        cardbank.setText(cardModel.getBank());
        cardnumber.setText(cardModel.getCardnumber());
        cardname.setText(cardModel.getCardname());
    }

    // 原有的返回键逻辑可以保留
    @Override
    public void onBackPressed() {
        if (mBackPressed + TIME_INTERVAL > System.currentTimeMillis()) {
            super.onBackPressed();
            return;
        } else {
            Toast.makeText(getBaseContext(), "Press back again to exit", Toast.LENGTH_SHORT).show();
        }
        mBackPressed = System.currentTimeMillis();
    }
}

这样修改之后，当你点击RecyclerView里的任意卡片时，MainActivity中的rv_card_card这个RelativeLayout就会显示出来，并且里面的三个TextView会自动填充对应卡片的银行名称、卡号和持卡人姓名啦~

内容的提问来源于stack exchange，提问作者hmotamed