foodcheck/ListAdapter.java

package com.example.health.foodlist;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import com.example.health.Bean.FoodBean;
import com.example.health.R;

import java.util.List;

public class ListAdapter extends BaseAdapter {
    Context context;
    List<FoodBean>mDatas;

    public ListAdapter(Context context, List<FoodBean> mDatas) {
        this.context = context;
        this.mDatas = mDatas;
    }
//决定了ListView展示列表的行数
    @Override
    public int getCount() {
        return mDatas.size();
    }
//返回指定位置对应的数据
    @Override
    public Object getItem(int position) {
        return mDatas.get(position);
    }
//返回指定位置对应的id
    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder = null;
        if (convertView == null) {
            convertView = LayoutInflater.from(context).inflate(R.layout.foodlist,null);//将布局转换成view对象的方法
            holder = new ViewHolder(convertView);
            convertView.setTag(holder);
        }else{
            holder = (ViewHolder) convertView.getTag();
        }
//加载控件显示的内容
//获取集合指定位置的数据
        FoodBean foodBean = mDatas.get(position);
        holder.iv.setImageResource(foodBean.getPicID());
        holder.fname.setText(foodBean.getFoodName());
        holder.fcalo.setText(foodBean.getFoodCalorie());//这三步用于显示内容
        return convertView;
    }

    class ViewHolder{
        ImageView iv;
        TextView fname,fcalo;
        public ViewHolder(View view){
            iv = view.findViewById(R.id.item_foodpic);
            fname = view.findViewById(R.id.item_foodtitle);
            fcalo = view.findViewById(R.id.item_calorie);
        }
    }
}