《第二行代码》 第一章ListView,GridView

列表控件，如果每个item显示的内容一样，可以使用ListView来实现

它的关键是Adapter

示例规范的GoodsAdapter

public class GoodsAdapter extends BaseAdapter {

private Context context;
//如果构造方法中有传入，不用初始化也可以
private List<GoodsBean> goodsBeanList ;

public GoodsAdapter(Context context, List<GoodsBean> goodsBeanList) {
    this.context = context;
    this.goodsBeanList = goodsBeanList;
}

@Override
public int getCount() {
    return goodsBeanList.size();
}

@Override
public GoodsBean getItem(int position) {
    return goodsBeanList.get(position);
}

/**
 * 一般用于bean中有id的，我们这个展示的没有就返回0即可
 * @param position
 * @return
 */
@Override
public long getItemId(int position) {
    return 0;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    ViewHolder holder = null;
    if (convertView == null){
        convertView = LayoutInflater.from(context).inflate(R.layout.item_lv, parent, false);
        holder = new ViewHolder(convertView);
        convertView.setTag(holder);
    } else {
        holder = (ViewHolder)convertView.getTag();
    }

    holder.tvName.setText(goodsBeanList.get(position).getGoodsName());

    return convertView;
}

//用静态
static class ViewHolder {
    ImageView img;
    TextView tvName;
    public ViewHolder(View view){
        img = view.findViewById(R.id.iv_good);
        tvName = view.findViewById(R.id.tv_name);
    }
}
}

相关的类：
GoodsBean.class

public class GoodsBean {
private String goodsUrl;
private String goodsName;

public GoodsBean(String goodsUrl, String goodsName) {
    this.goodsUrl = goodsUrl;
    this.goodsName = goodsName;
}

public String getGoodsUrl() {
    return goodsUrl;
}

public void setGoodsUrl(String goodsUrl) {
    this.goodsUrl = goodsUrl;
}

public String getGoodsName() {
    return goodsName;
}

public void setGoodsName(String goodsName) {
    this.goodsName = goodsName;
}
}  

item_lv.xml

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

<ImageView
    android:id="@+id/iv_good"
    android:layout_width="200dp"
    android:layout_height="148dp"
    android:scaleType="centerCrop"
    android:src="@mipmap/img_apply_talent_bg"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"/>

<TextView
    android:id="@+id/tv_name"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    app:layout_constraintTop_toTopOf="@id/iv_good"
    app:layout_constraintBottom_toBottomOf="@id/iv_good"
    app:layout_constraintLeft_toRightOf="@id/iv_good"
    android:layout_marginLeft="20dp"
    tools:text="路飞123"
    />
<View
    android:layout_width="match_parent"
    android:layout_height="1dp"
    android:background="#eeeeee"
    app:layout_constraintTop_toBottomOf="@id/iv_good"/>

</androidx.constraintlayout.widget.ConstraintLayout>  

记得避免复用产生的问题，有if就有else就对了

二、GridView

它比ListView多了个几个属性，其他的都一样

    android:horizontalSpacing="1dp"
    android:numColumns="3"
    android:verticalSpacing="1dp"