最近在写一个类似于点餐系统的项目，想起来还没写过博客，而且目前面临着即将走出校门找工作，所以打算写几篇博客，顺便记录一下用到的知识点，方便以后查看。回归主题，今天写的是关于ListView中每个Item中商品数量的增加删除并且总价跟着改变。
效果图如下
首先介绍每个Item中商品数量改变，一开始只是知道每个Item点击有OnItemClickListener方法，但是不知道能不能实现单个Item内如果有点击时间之后的处理，所以就尝试了一下在Adapter中给相应的控件加监听事件，结果实现了，代码如下。
每个Item的布局如下
<?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"
android:orientation="vertical">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"
android:orientation="horizontal">
<CheckBox
android:id="@+id/cb_diy_item_check"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="20dp"
android:gravity="center_vertical" />
<TextView
android:id="@+id/tv_diy_item_wine"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:gravity="center"
android:text="金酒"
android:textSize="20sp" />
<TextView
android:id="@+id/tv_diy_item_unit"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:gravity="center"
android:text="10ml/次"
android:textSize="20sp" />
<LinearLayout
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1">
<TextView
android:id="@+id/tv_diy_item_minus"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_weight="1"
android:text="－"
android:textSize="20sp" />
<TextView
android:id="@+id/tv_diy_item_total"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="3"
android:gravity="center"
android:text="0"
android:textSize="20sp" />
<TextView
android:id="@+id/tv_diy_item_add"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_weight="1"
android:text="＋"
android:textSize="20sp" />
</LinearLayout>
<TextView
android:id="@+id/tv_diy_item_count"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:gravity="center"
android:text="￥0.00"
android:textSize="20sp" />
</LinearLayout>
</LinearLayout>
相应的Adapter代码为
package com.lylk.hcwy.adapter;
import android.content.Context;
import android.os.Handler;
import android.os.Message;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.TextView;
import android.widget.Toast;
import com.lylk.hcwy.R;
import java.util.LinkedList;
/**
* Created by LYLK on 2017/5/4.
*/
public class DiyListAdapter extends BaseAdapter {
private Context context;
private LinkedList<String> name;
private LinkedList<String> unit;
private LinkedList<Integer> unit_price;
private Handler handler;
public DiyListAdapter(Context context,LinkedList<String> name,LinkedList<String> unit,
LinkedList<Integer> unit_price,Handler handle) {
this.context = context;
this.name = name;
this.unit = unit;
this.unit_price = unit_price;
this.handler = handle;
}
@Override
public int getCount() {
return name.size();
}
@Override
public Object getItem(int position) {
return name.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder;
if (convertView == null) {
convertView = LayoutInflater.from(context).inflate(R.layout.diy_item, null);
viewHolder = new ViewHolder();
viewHolder.ck = (CheckBox) convertView.findViewById(R.id.cb_diy_item_check);
viewHolder.tv_name = (TextView) convertView.findViewById(R.id.tv_diy_item_wine);
viewHolder.tv_unit = (TextView) convertView.findViewById(R.id.tv_diy_item_unit);
viewHolder.tv_minus = (TextView) convertView.findViewById(R.id.tv_diy_item_minus);
viewHolder.tv_total = (TextView) convertView.findViewById(R.id.tv_diy_item_total);
viewHolder.tv_add = (TextView) convertView.findViewById(R.id.tv_diy_item_add);
viewHolder.tv_count = (TextView) convertView.findViewById(R.id.tv_diy_item_count);
convertView.setTag(viewHolder);
}else {
viewHolder = (ViewHolder) convertView.getTag();
}
init(viewHolder, position,unit_price.get(position));
return convertView;
}
private void init(final ViewHolder viewHolder, int position, final int price) {
viewHolder.tv_name.setText(name.get(position));
viewHolder.ck.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if(isChecked){
viewHolder.tv_total.setText("1");
viewHolder.tv_count.setText("¥"+price);
Message msg = Message.obtain();
msg.arg1 = price;
handler.sendMessage(msg);
}else {
int pre_total = Integer.parseInt(viewHolder.tv_total.getText().toString());
int pre_count = pre_total*price;
viewHolder.tv_total.setText("0");
viewHolder.tv_count.setText("¥0");
Message msg = Message.obtain();
msg.arg1 = 0-pre_count;
handler.sendMessage(msg);
}
}
});
viewHolder.tv_minus.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String total = viewHolder.tv_total.getText().toString();
if(total.equals("0")){
Toast.makeText(context,"此酒未被选择",Toast.LENGTH_SHORT).show();
}else if(total.equals("1")){
viewHolder.tv_total.setText("0");
viewHolder.ck.setChecked(false);
// Message msg = Message.obtain();
// msg.arg1 = 0-price;
// handler.sendMessage(msg);
}else {
int num = Integer.parseInt(total);
num--;
viewHolder.tv_count.setText("¥"+price*num);
viewHolder.tv_total.setText(String.valueOf(num));
Message msg = Message.obtain();
msg.arg1 = 0-price;
handler.sendMessage(msg);
}
}
});
viewHolder.tv_add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String total = viewHolder.tv_total.getText().toString();
int num = Integer.parseInt(total);
if(total.equals("0")){
viewHolder.ck.setChecked(true);
num++;
viewHolder.tv_count.setText("¥"+price*num);
viewHolder.tv_total.setText(String.valueOf(num));
// Message msg = Message.obtain();
// msg.arg1 = price;
// handler.sendMessage(msg);
}else {
num++;
viewHolder.tv_count.setText("¥"+price*num);
viewHolder.tv_total.setText(String.valueOf(num));
Message msg = Message.obtain();
msg.arg1 = price;
handler.sendMessage(msg);
}
}
});
int total = Integer.parseInt(viewHolder.tv_total.getText().toString());
viewHolder.tv_count.setText("¥"+price*total);
}
private class ViewHolder {
public CheckBox ck;
public TextView tv_name;
public TextView tv_unit;
public TextView tv_minus;
public TextView tv_total;
public TextView tv_add;
public TextView tv_count;
}
}
只需要在绑定布局的时候加入相应的点击时间就可以实现。
viewHolder.tv_minus.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String total = viewHolder.tv_total.getText().toString();
if(total.equals("0")){
Toast.makeText(context,"此酒未被选择",Toast.LENGTH_SHORT).show();
}else if(total.equals("1")){
viewHolder.tv_total.setText("0");
viewHolder.ck.setChecked(false);
// Message msg = Message.obtain();
// msg.arg1 = 0-price;
// handler.sendMessage(msg);
}else {
int num = Integer.parseInt(total);
num--;
viewHolder.tv_count.setText("¥"+price*num);
viewHolder.tv_total.setText(String.valueOf(num));
Message msg = Message.obtain();
msg.arg1 = 0-price;
handler.sendMessage(msg);
}
}
});
viewHolder.tv_add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String total = viewHolder.tv_total.getText().toString();
int num = Integer.parseInt(total);
if(total.equals("0")){
viewHolder.ck.setChecked(true);
num++;
viewHolder.tv_count.setText("¥"+price*num);
viewHolder.tv_total.setText(String.valueOf(num));
// Message msg = Message.obtain();
// msg.arg1 = price;
// handler.sendMessage(msg);
}else {
num++;
viewHolder.tv_count.setText("¥"+price*num);
viewHolder.tv_total.setText(String.valueOf(num));
Message msg = Message.obtain();
msg.arg1 = price;
handler.sendMessage(msg);
}
}
});
接下来说一下如何实现动态的实现总价的修改，其实也很简单，利用一个Handler即可实现，写这部分功能之前想了很多方法，比如遍历ListView什么的，但是最后一一排除之后选择使用Handler来实现。在此之前也没有查过资料，只是想验证一下自己的想法是否可以实现，最终实现完成之后查看资料发现很多人都是使用这种方式实现的，瞬间感觉自己想的还是挺对的。废话不多说，直接看代码吧。
首先在Fragment中定义一个Handler
public Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
Double pre_count = Double.parseDouble(tv_count.getText().toString());
super.handleMessage(msg);
tv_count.setText(String.valueOf(pre_count+msg.arg1));
}
};
然后在Adapter构造函数中把这个Handler传递过去，在Adapter中每个商品价格改变的位置把改变的价格发送回去就可以了。
viewHolder.tv_add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String total = viewHolder.tv_total.getText().toString();
int num = Integer.parseInt(total);
if(total.equals("0")){
viewHolder.ck.setChecked(true);
num++;
viewHolder.tv_count.setText("¥"+price*num);
viewHolder.tv_total.setText(String.valueOf(num));
// Message msg = Message.obtain();
// msg.arg1 = price;
// handler.sendMessage(msg);
}else {
num++;
viewHolder.tv_count.setText("¥"+price*num);
viewHolder.tv_total.setText(String.valueOf(num));
Message msg = Message.obtain();
msg.arg1 = price;
handler.sendMessage(msg);
}
}
});
以上就是这次记录的内容，还有一个小小的问题，就是现在没有测试在Adadpter中给空间添加的点击事件与OnItemClickListener会不会产生冲突，等之后测试一下在写测试结果吧，现在就先写这么多。第一次写博客，写的不好请大家见谅，有什么不好的地方希望大家能给指正。
