CardView

用于通过带有圆角布局和特定阴影效果来显示各种数据。CardView 可以用于创建 ListView 或 RecyclerView 中的条目布局。

创建CardView

1. CardView 条目布局

一个用于表示 RecyclerView 中单个条目布局的 XML 布局文件。

<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="220dp"
    android:layout_margin="8dp"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    app:cardBackgroundColor="@color/black"
    app:cardElevation="20dp"
    app:cardCornerRadius="40dp">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <ImageView
            android:id="@+id/image_view"
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:src="@drawable/basketball"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <TextView
            android:id="@+id/text_view"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginStart="16dp"
            android:text="Title"
            android:textSize="48sp"
            android:textColor="@color/black"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />


    </androidx.constraintlayout.widget.ConstraintLayout>

</androidx.cardview.widget.CardView>

2. RecyclerView

在 Activity 中创建一个 RecyclerView 并初始化。
activity_main.xml 布局文件的内容，如下所示

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ImageView
        android:id="@+id/imageView3"
        android:layout_width="0dp"
        android:layout_height="220dp"
        android:layout_marginTop="4dp"
        android:src="@drawable/header"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginTop="16dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/imageView3" />


</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity.java 文件的内容，如下所示

package com.stewednoodles.sportsapp;

import android.os.Bundle;

import androidx.activity.EdgeToEdge;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.graphics.Insets;
import androidx.core.view.ViewCompat;
import androidx.core.view.WindowInsetsCompat;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private RecyclerView recyclerView;
    private List<Sport> sports;

    private SportAdapter sportAdapter;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        EdgeToEdge.enable(this);
        setContentView(R.layout.activity_main);
        ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main), (v, insets) -> {
            Insets systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars());
            v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);
            return insets;
        });

        recyclerView = findViewById(R.id.recycler_view);
        sports = new ArrayList<>() ;
        sports.add(new Sport("Football", R.drawable.football));
        sports.add(new Sport("Basketball", R.drawable.basketball));
        sports.add(new Sport("Ping Ping", R.drawable.ping));
        sports.add(new Sport("Volleyball", R.drawable.volley));
        sports.add(new Sport("Tennis", R.drawable.tennis));

        sportAdapter = new SportAdapter(sports);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setAdapter(sportAdapter);
    }
}

3. Model Class 模型类

表示用于保存 RecyclerView 每个条目信息的数据结构。

package com.stewednoodles.sportsapp;

public class Sport {
    private String sportName;
    private int sportImage;

    public Sport(String sportName, int sportImage) {
        this.sportName = sportName;
        this.sportImage = sportImage;
    }

    public String getSportName() {
        return sportName;
    }

    public void setSportName(String sportName) {
        this.sportName = sportName;
    }

    public int getSportImage() {
        return sportImage;
    }

    public void setSportImage(int sportImage) {
        this.sportImage = sportImage;
    }
}

4. Adapter Class 适配器类

包含所有与 RecyclerView 实现相关的方法（创建、绑定以及确定条目数量）。

package com.stewednoodles.sportsapp;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.List;

public class SportAdapter extends RecyclerView.Adapter<SportAdapter.SportViewHolder> {
    private List<Sport> sports;

    public SportAdapter(List<Sport> sports) {
        this.sports = sports;
    }

    @NonNull
    @Override
    public SportViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        // 从XML布局中创建View
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.card_item_layout, parent, false);
        return new SportViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull SportViewHolder holder, int position) {
        // 获取数据
        Sport sport = sports.get(position);

        // 绑定数据
        holder.backgroundImageView.setImageResource(sport.getSportImage());
        holder.titleTextView.setText(sport.getSportName());
    }

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

    public static class SportViewHolder extends RecyclerView.ViewHolder {
        ImageView backgroundImageView;
        TextView titleTextView;
        public SportViewHolder(View itemView) {
            super(itemView);
            // 查找 View
            backgroundImageView = itemView.findViewById(R.id.image_view);
            titleTextView = itemView.findViewById(R.id.text_view);
        }
    }
}

5. View Holder

保存每个条目布局中视图的引用，用于优化视图查找效率。View Holder 的示例代码，见 4. Adapter Class 适配器类

运行效果

示例代码的运行效果，如下所示