一、layout
1、activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
<!-- 由于RecyclerView不是内置在系统SDK当中的,所以需要把完整的包路径写出来 -->
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</LinearLayout>
2、fruit_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="5dp"
>
<!--
android:orientation="vertical" 将LinearLayout设置为垂直布局
android:layout_width="100dp" 将宽度设置为100dp
-->
<!--
android:layout_margin="5dp" 让子项之间相隔5dp
-->
<ImageView
android:id="@+id/fruit_image"
android:layout_width="64dp"
android:layout_height="62dp"
android:layout_gravity="center_horizontal" />
<TextView
android:id="@+id/fruit_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="left"
android:layout_marginTop="10dp"/>
<!--
android:layout_gravity="center_horizontal" 设置水平居中
android:layout_marginTop="10dp" 让文字与图片保持一些距离 -->
<!--
android:layout_gravity="left"
居左对齐,等下文字的长度变长,居中会显得很奇怪-->
</LinearLayout>
<!--为指定的RecyclerView的子项指定我们自定义的布局fruit_item.xml-->
二、Java代码
1、Fruit类
package com.example.recycleviewtest;
//新建类Fruit,作为RecyclerView适配器的适配类型
public class Fruit {
private String name;
private int imageId;
public Fruit(String name,int imageId){
this.imageId=imageId;
this.name=name;
}
public int getImageId() {
return imageId;
}
public String getName() {
return name;
}
}
2、FruitAdapter适配器
package com.example.recycleviewtest;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import java.util.List;
/**
* 创建了自定义的适配器,继承于RecyclerView.Adapter,将泛型指定为FruitAdapter.ViewHolder
*/
public class FruitAdapter extends RecyclerView.Adapter<FruitAdapter.ViewHolder> {
private List<Fruit> mFruitList;
/**
* 定义内部类ViewHolder 继承自 RecyclerView.ViewHolder
*/
static class ViewHolder extends RecyclerView.ViewHolder {
View fruitView;//子项最外层布局实例
ImageView fruitImage;
TextView fruitName;
/**
* 构造参数中传入参数view
* @param view RecyclerView子项的最外层布局
*/
public ViewHolder(@NonNull View view) {
super(view);
fruitView=view;
fruitImage=(ImageView)view.findViewById(R.id.fruit_image);
fruitName=(TextView)view.findViewById(R.id.fruit_name);
}
}
/**
* 传入数据源
* 构造函数
* @param fruitList
*/
public FruitAdapter(List<Fruit> fruitList){
mFruitList=fruitList;
}
/**
* 重写onCreateViewHolder方法,用于创建ViewHolder实例,并把加载出来的布局传入到构造函数中,最后将ViewHolder的实例返回
* @param parent
* @param viewType
* @return
*/
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view= LayoutInflater.from(parent.getContext())
.inflate(R.layout.fruit_item,parent,false);
//声明为final,这样匿名内部类中也能获取
final ViewHolder holder=new ViewHolder(view);
//重写onClick方法,为Fruit的视图view设置单击监听器
holder.fruitView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//获得被单击的item的实例
int position=holder.getAdapterPosition();
Fruit fruit=mFruitList.get(position);
//提示信息
Toast.makeText(v.getContext(),"You clicked view "+fruit.getName(),Toast.LENGTH_SHORT).show();
}
});
//重写OnClick方法,为Fruit的图片image也设置单击监听器
holder.fruitImage.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int position=holder.getAdapterPosition();
Fruit fruit=mFruitList.get(position);
Toast.makeText(v.getContext(),"You cliked image "+fruit.getName(),Toast.LENGTH_SHORT).show();
}
});
return holder;
}
/**
* 对RecyclerView子项的数据进行赋值,会在每个子项被滚动到屏幕内的时候执行
* @param holder
* @param position
*/
@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
Fruit fruit=mFruitList.get(position);
holder.fruitImage.setImageResource(fruit.getImageId());
holder.fruitName.setText(fruit.getName());
}
/**
* 告诉RecyclerView有多少子项
* @return
*/
@Override
public int getItemCount() {
return mFruitList.size();
}
}
3、主方法MainActivity
package com.example.recycleviewtest;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.GridLayoutManager;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import androidx.recyclerview.widget.StaggeredGridLayoutManager;
import android.os.Bundle;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
public class MainActivity extends AppCompatActivity {
private List<Fruit> fruitList=new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//初始化水果数据
initFruits();
//获取RecyclerView的实例
RecyclerView recyclerView=(RecyclerView)findViewById(R.id.recycler_view);
//参数1:把布局分成三列 参数2:让布局纵向排列
//指定RecyclerView的布局方式为 3列纵向瀑布流布局
StaggeredGridLayoutManager layoutManager=new StaggeredGridLayoutManager(
3,StaggeredGridLayoutManager.VERTICAL);
// GridLayoutManager layoutManager=new GridLayoutManager(this,5,GridLayoutManager.VERTICAL,false);
//指定RecyclerView的布局方式为线性布局
// LinearLayoutManager layoutManager=new LinearLayoutManager(this);
//设置布局管理器layoutManager的布局方向为水平,默认为垂直
// layoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);
recyclerView.setLayoutManager(layoutManager);
//为RecyclerView设置Adapter
FruitAdapter adapter=new FruitAdapter(fruitList);
recyclerView.setAdapter(adapter);
}
private void initFruits() {
for (int i = 0; i < 3 ; i++) {
// Fruit apple=new Fruit("Apple",R.drawable.apple_pic);
Fruit apple=new Fruit(getRandomLengthName("Apple"),R.drawable.apple_pic);
fruitList.add(apple);
Fruit banana=new Fruit(getRandomLengthName("Banana"),R.drawable.banana_pic);
fruitList.add(banana);
Fruit orange=new Fruit(getRandomLengthName("Orange"),R.drawable.orange_pic);
fruitList.add(orange);
Fruit pear=new Fruit(getRandomLengthName("Pear"),R.drawable.pear_pic);
fruitList.add(pear);
Fruit watermelon=new Fruit(getRandomLengthName("Watermelon"),R.drawable.watermelon_pic);
fruitList.add(watermelon);
Fruit grape=new Fruit(getRandomLengthName("Grape"),R.drawable.grape_pic);
fruitList.add(grape);
Fruit pineapple=new Fruit(getRandomLengthName("Pineapple"),R.drawable.pineapple_pic);
fruitList.add(pineapple);
Fruit strawberry=new Fruit(getRandomLengthName("Strawberry"),R.drawable.strawberry_pic);
fruitList.add(strawberry);
}
}
private String getRandomLengthName(String name) {
Random random=new Random();
int length=random.nextInt(20)+1;
StringBuilder builder=new StringBuilder();
for (int i = 0; i < length; i++) {
builder.append(name);
}
return builder.toString();
}
}