最近在做电商APP，实现购物车功能，按照要求需点击加减改变数量，计算每条数据的小计，及计算全部数据总价。之前都是使用SQLite保存数据，实现起来逻辑处理很麻烦。今天利用下班时间研究了下，写了个Demo实现了想要的功能。下面贴出主要代码，请大家批评指导。

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MainActivity.java

package com.srain.activity;import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.TextView;import com.srain.listviewdemo.R;
import com.srain.adapter.ListViewAdapter;public class MainActivity extends Activity {private List<Map<String, Object>> mData;private ListView listview;private ListViewAdapter adapter;private TextView tvAmount;private double amount = 0;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);initView();}private void initView() {mData = getData();tvAmount = (TextView) findViewById(R.id.tv_amount);listview = (ListView) findViewById(R.id.listleft);adapter = new ListViewAdapter(this, mLeftListOnItemClick, mData);listview.setAdapter(adapter);listview.setOnItemClickListener(mLeftListOnItemClick);tvAmount.setText("" + amount);TextView tvSub = (TextView) findViewById(R.id.tv_sub);tvSub.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View arg0) {for (Map<String, Object> map : mData) {Log.e("count", map.get("count").toString());}}});// setlistViewLeft.setChoiceMode(ListView.CHOICE_MODE_SINGLE);// setlistViewLeft.setItemChecked(0, true);// setlistViewLeft.setSelection(0);}private List<Map<String, Object>> getData() {amount = 0;List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();Map<String, Object> map = new HashMap<String, Object>();map.put("price", 12);map.put("count", 2);list.add(map);map = new HashMap<String, Object>();map.put("price", 150);map.put("count", 3);list.add(map);map = new HashMap<String, Object>();map.put("price", 120);map.put("count", 8);list.add(map);map = new HashMap<String, Object>();map.put("price", 112);map.put("count", 6);list.add(map);map = new HashMap<String, Object>();map.put("price", 102);map.put("count", 6);list.add(map);// for (Map<String, Object> pram : list) {// int count = Integer.valueOf(pram.get("count").toString());// double price = Double.valueOf(pram.get("price").toString());// double sub = count * price;// amount = amount + sub;// }for (int i = 0; i < list.size(); i++) {Map<String, Object> pram = list.get(i);int count = Integer.valueOf(pram.get("count").toString());double price = Double.valueOf(pram.get("price").toString());double sub = count * price;amount = amount + sub;Log.e("amount", "amount" + amount + "sub" + sub + "i" + i);}return list;}public class MyListener implements View.OnClickListener {private TextView tvcount;private TextView tvsub;private int count;private double price;private int position;public MyListener() {}public MyListener(TextView tvcount, TextView tvsub, int count,double price, int position) {this.tvcount = tvcount;this.tvsub = tvsub;this.count = count;this.price = price;this.position = position;}@Overridepublic void onClick(View view) {switch (view.getId()) {case R.id.tv_add:count++;double subtotle = price * count;tvcount.setText("" + count);tvsub.setText("" + subtotle);amount += price;tvAmount.setText("" + amount);Map<String, Object> pram = mData.get(position);pram.put("price", price);pram.put("count", count);break;case R.id.tv_del:break;default:break;}}}// OnClickListener bPop = new OnClickListener() {// @Override// public void onClick(View v) {// for(int i=0;i<list.getCount();i++){// if(MyAdapter.isSelected.get(i)){// ViewHolder vHollder = (ViewHolder) list.getChildAt(i).getTag();// Log.i(TAG, "--onClick --"+vHollder.title.getText());// }// }// }// };AdapterView.OnItemClickListener mLeftListOnItemClick = new AdapterView.OnItemClickListener() {public void onItemClick(AdapterView<?> parent, View view, int position,long id) {Map<String, Object> map = mData.get(position);TextView tvadd = (TextView) view.findViewById(R.id.tv_add);TextView tvcount = (TextView) view.findViewById(R.id.tv_count);TextView tvsubtotal = (TextView) view.findViewById(R.id.tv_subtotal);int count = Integer.valueOf(map.get("count").toString());double price = Double.valueOf(map.get("price").toString());double subtotal = Double.valueOf(tvsubtotal.getText().toString());tvadd.setOnClickListener(new MyListener(tvcount, tvsubtotal, count,price, position));Intent intent = new Intent();intent.setClass(MainActivity.this, DetailActivity.class);startActivity(intent);// adapter.setSelectItem(position);// adapter.notifyDataSetInvalidated();// adapter.notifyDataSetChanged();}};}

ListViewAdapter.java

package com.srain.adapter;import java.util.List;
import java.util.Map;import android.content.Context;
import android.graphics.Color;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.BaseAdapter;
import android.widget.TextView;import com.srain.listviewdemo.R;public class ListViewAdapter extends BaseAdapter {private LayoutInflater mInflater;private List<Map<String, Object>> mData;private OnItemClickListener listener;public ListViewAdapter(Context context, OnItemClickListener listener,List<Map<String, Object>> mData) {this.mData = mData;this.mInflater = LayoutInflater.from(context);this.listener = listener;}public int getCount() {return mData.size();}public Object getItem(int arg0) {return mData.get(arg0);}public long getItemId(int arg0) {return arg0;}public View getView(int position, View convertView, ViewGroup parent) {Map<String, Object> map = mData.get(position);ViewHolder holder = null;if (convertView == null) {holder = new ViewHolder();convertView = mInflater.inflate(R.layout.leftview, null);holder.tvadd = (TextView) convertView.findViewById(R.id.tv_add);holder.tvdel = (TextView) convertView.findViewById(R.id.tv_del);holder.tvConut = (TextView) convertView.findViewById(R.id.tv_count);holder.tvSubtotal = (TextView) convertView.findViewById(R.id.tv_subtotal);convertView.setTag(holder);} else {holder = (ViewHolder) convertView.getTag();}int count = Integer.valueOf(map.get("count").toString());double price = Double.valueOf(map.get("price").toString());holder.tvConut.setText(count + "");holder.tvSubtotal.setText(price * count + "");if (position == selectItem) {convertView.setBackgroundColor(Color.RED);} else {convertView.setBackgroundColor(Color.TRANSPARENT);}return convertView;}public void setSelectItem(int selectItem) {this.selectItem = selectItem;}private int selectItem = 0;public final class ViewHolder {public TextView tvadd;public TextView tvdel;public TextView tvConut;public TextView tvSubtotal;}
}