Question

我有3个名称，数量和价格的数组。

我使用Listview通过SimpleAdapter显示它们。最重要的是，我每排有2个按钮，用于控制数量 - 加号和减号。

点击加号或减号按钮时，数量会发生变化，该行的小计也会更新。

如果数量= 1，单击减号按钮时，它将保持为1;

到目前为止所有功能都正常工作。

爪哇

int cal_quantity;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main8);

List<HashMap<String, String>> aList = new ArrayList<HashMap<String, String>>();

final String name[]={"apple","orange","pear"};
final String quantity[]={"1","2","3"};
final String price[]={"5","10","2"};

for(int i=0;i<name.length;i++){
    HashMap<String, String> map = new HashMap<>();
    map.put("name",name[i]);
    map.put("quantity",quantity[i]);
    map.put("price",price[i]);
    aList.add(map);
}

String[] from = {"name","quantity","price"};
int[] to = {R.id.name,R.id.quantity,R.id.price};

SimpleAdapter adapter = new SimpleAdapter(this, aList, R.layout.main7, from, to){
    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {

        View v = super.getView(position, convertView, parent);
        final TextView tv_quantity=(TextView)v.findViewById(R.id.quantity);
        final TextView tv_price=(TextView)v.findViewById(R.id.price);
        final TextView tv_total=(TextView)v.findViewById(R.id.total);

        final int get_quantity = Integer.parseInt(tv_quantity.getText().toString());
        final double get_price= Double.parseDouble(tv_price.getText().toString());
        final double get_total=get_quantity*get_price;
        tv_total.setText(get_total+"");

        Button minus=(Button)v.findViewById(R.id.minus);
        minus.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                cal_quantity=Integer.parseInt(tv_quantity.getText().toString());
                if(cal_quantity!=1){
                    cal_quantity=cal_quantity-1;
                }
                tv_quantity.setText(cal_quantity+"");
                double get_total=cal_quantity*get_price;
                tv_total.setText(get_total+"");
            }
        });

        Button plus=(Button)v.findViewById(R.id.plus);
        plus.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                cal_quantity=Integer.parseInt(tv_quantity.getText().toString());
                cal_quantity=cal_quantity+1;
                tv_quantity.setText(cal_quantity+"");
                double get_total=cal_quantity*get_price;
                tv_total.setText(get_total+"");
            }
        });
        return v;
    }
};

ListView listView = (ListView) findViewById(R.id.listview);
listView.setAdapter(adapter);

}

XML

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main8"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.yu.singleton.Main8Activity"
android:orientation="vertical">

<LinearLayout
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_weight="0.3"
    android:layout_height="match_parent">

    <ListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/listview" />
</LinearLayout>

<LinearLayout
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:background="@android:color/holo_blue_dark"
    android:layout_weight="0.7"
    android:layout_height="match_parent">

    <TextView
        android:text="Total"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/textView3"
        android:textAlignment="center"
        android:textSize="36sp" />
</LinearLayout>
</LinearLayout>

我的问题是如何添加每行的小计，然后在Listview下方的Textview（总计）中显示

Answer 1

您现在拥有的总数已经反映了列表视图中每个行项的子总数。

我建议将您的hashmap列表作为活动的实例变量移出，以便它具有更广泛的范围，同时声明另一个变量来存储您的总数。

编写一个迭代你的hashmap列表的方法，并为每次迭代，获取数量，获取价格并将它们相乘。在每次迭代中将此值添加到总变量中，并在迭代器完成后，将总textview的值设置为等于总变量。在此方法开始时将total变量设置为等于0.0。

在每个按钮的最后一行调用此方法＆＃39;监听器。但是，我建议您以面向对象的方式执行此操作，其中您的hashmap列表可以只是一个简单的对象列表。帮助清晰。

int cal_quantity;
private int total;
**private TextView grandTotal_TV;**

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main8);
**grandTotal_TV = findViewById(R.id.TextView3);**

List<HashMap<String, String>> aList = new ArrayList<HashMap<String, String>>();

final String name[]={"apple","orange","pear"};
final String quantity[]={"1","2","3"};
final String price[]={"5","10","2"};

for(int i=0;i<name.length;i++){
    HashMap<String, String> map = new HashMap<>();
    map.put("name",name[i]);
    map.put("quantity",quantity[i]);
    map.put("price",price[i]);
    aList.add(map);
}

String[] from = {"name","quantity","price"};
int[] to = {R.id.name,R.id.quantity,R.id.price};

SimpleAdapter adapter = new SimpleAdapter(this, aList, R.layout.main7, from, to){
    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {

        View v = super.getView(position, convertView, parent);
        final TextView tv_quantity=(TextView)v.findViewById(R.id.quantity);
        final TextView tv_price=(TextView)v.findViewById(R.id.price);
        final TextView tv_total=(TextView)v.findViewById(R.id.total);

        final int get_quantity = Integer.parseInt(tv_quantity.getText().toString());
        final double get_price= Double.parseDouble(tv_price.getText().toString());
        final double get_total=get_quantity*get_price;
        tv_total.setText(get_total+"");

        Button minus=(Button)v.findViewById(R.id.minus);
        minus.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                cal_quantity=Integer.parseInt(tv_quantity.getText().toString());
                if(cal_quantity!=1){
                    cal_quantity=cal_quantity-1;
                }
                tv_quantity.setText(cal_quantity+"");
                double get_total=cal_quantity*get_price;
                tv_total.setText(get_total+"");
                **calculateTotal();**
            }
        });

        Button plus=(Button)v.findViewById(R.id.plus);
        plus.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                cal_quantity=Integer.parseInt(tv_quantity.getText().toString());
                cal_quantity=cal_quantity+1;
                tv_quantity.setText(cal_quantity+"");
                double get_total=cal_quantity*get_price;
                tv_total.setText(get_total+"");
                **calculateTotal();**
            }
        });
        return v;
    }
};

ListView listView = (ListView) findViewById(R.id.listview);
listView.setAdapter(adapter);

}
**private void calculateTotal()
    {
        total=0.0;
        for(int i = 0; i<aList.size(); i++)
        {
            HashMap<String, String> map =  aList.get(i);
            int qty = Integer.parseInt(map.get("quantity"));
            double price = Double.parseDouble(map.get("price"));
            total+=qty*price;

        }
        grandTotal_TV.setText(total);
    }**

Answer 2

无论何时加减，都应将数量保存到数据源中以下是将数量保存到数据源并在减去时计算总数的方法，您应该对加号

执行相同操作

minus.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        cal_quantity = Integer.parseInt(tv_quantity.getText().toString());
        if (cal_quantity != 1) {
            cal_quantity = cal_quantity - 1;
        }

        // Save the quantity to your datasource (aList)
        aList.get(position).put("quantity", "" + cal_quantity);

        // Calculate total
        int total = 0;
        Log.d("TAG", "start total = " +total);
        for (int i = 0; i < aList.size(); i++) {
            Log.d("TAG", "at "+i+ " quantity = " +aList.get(i).get("quantity"));
            total += Integer.parseInt(aList.get(i).get("quantity")) * Integer.parseInt(aList.get(i).get("price"));
            Log.d("TAG", "at "+i+ " total = " +total);
        }
        // Display total, currently I use Toast, you can display it into your TextView
        Toast.makeText(getApplicationContext(), "Total " + total, Toast.LENGTH_SHORT).show();

        ...
    }
});

Android listview simpleAdapter获取每行的最后一列Textview的总和

2 个答案: