如何在列表视图中对文本视图中的值求和和相乘并在吐司中显示它们?

Question

我是编程新手，如果你能帮我解决这个问题，那就太好了。我有一个活动，它有一个按钮和一个列表视图。列表视图上的值是名称、价格、类别和数量，并通过适配器定义。我想知道如何将每行的数量值乘以价格值并将所有这些值相加，并在单击按钮时在吐司中显示结果。这是它的图形，以便更好地理解它。

代码如下：

购物车列表活动.java

public class CartListActivity extends AppCompatActivity {
ListView userList;
UserCustomAdapter userAdapter;
ArrayList<User> userArray = new ArrayList<User>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_cart_list);
Button payBtn = (Button)findViewById(R.id.payBtn);
payBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Toast.makeText(getApplicationContext(), "Total: x€", Toast.LENGTH_SHORT).show();
}
});
/**
* add item in arraylist
*/
userArray.add(new User("Olives verdes", "1,20€", "Aperitius", "0"));
userArray.add(new User("Olives negres", "1,30€", "Aperitius", "0"));
userArray.add(new User("Cogombrets", "1,80€", "Aperitius","0"));
userArray.add(new User("Patates Lay's", "1,19€", "Aperitius","0"));
userArray.add(new User("Potet", "0,95€", "Bebè","0"));
userArray.add(new User("Biberó", "3,85€", "Bebè","0"));
userArray.add(new User("Tovalloletes", "1,10€", "Bebè","0"));
userArray.add(new User("Perxes de nadó", "1,95€", "Bebè","0"));
/**
* set item into adapter
*/
userAdapter = new UserCustomAdapter(CartListActivity.this, R.layout.view_row,
userArray);
userList = (ListView) findViewById(R.id.listView);
userList.setItemsCanFocus(false);
userList.setAdapter(userAdapter);
/**
* get on item click listener
*/
userList.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View v,
final int position, long id) {
Log.i("List View Clicked", "**********");
Toast.makeText(CartListActivity.this,
"List View Clicked:" + position, Toast.LENGTH_LONG)
.show();
}
});
}
}

用户自定义适配器.java

public class UserCustomAdapter extends ArrayAdapter<User> {
Context context;
int layoutResourceId;
ArrayList<User> data = new ArrayList<User>();
public UserCustomAdapter(Context context, int layoutResourceId,
ArrayList<User> data) {
super(context, layoutResourceId, data);
this.layoutResourceId = layoutResourceId;
this.context = context;
this.data = data;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View row = convertView;
UserHolder holder = null;
if (row == null) {
LayoutInflater inflater = ((Activity) context).getLayoutInflater();
row = inflater.inflate(layoutResourceId, parent, false);
holder = new UserHolder();
holder.textName = (TextView) row.findViewById(R.id.textView1);
holder.textPrice = (TextView) row.findViewById(R.id.textView2);
holder.textCategory = (TextView) row.findViewById(R.id.textView3);
holder.textQuantity = (TextView) row.findViewById(R.id.quantityTxt);
holder.btnEdit = (Button) row.findViewById(R.id.button1);
holder.btnDelete = (Button) row.findViewById(R.id.button2);
row.setTag(holder);
} else {
holder = (UserHolder) row.getTag();
}
final User user = data.get(position);
holder.textName.setText(user.getName());
holder.textPrice.setText(user.getPrice());
holder.textCategory.setText(user.getCategory());
holder.textQuantity.setText(user.getQuantity());
final UserHolder finalHolder = holder;
holder.btnEdit.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String value1 = finalHolder.textQuantity.getText().toString();
int a = Integer.parseInt(value1);
if(a <= 99) {
int sum = a + 1;
Log.i("Edit Button Clicked", "**********");
user.setQuantity(Integer.toString(sum));
finalHolder.textQuantity.setText(Integer.toString(sum));
}
}
});
holder.btnDelete.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String value2 = finalHolder.textQuantity.getText().toString();
int a = Integer.parseInt(value2);
if(a > 0) {
int substract = a - 1;
Log.i("Delete Button Clicked", "**********");
user.setQuantity(Integer.toString(substract));
finalHolder.textQuantity.setText(Integer.toString(substract));
}
}
});
return row;
}
static class UserHolder {
TextView textName;
TextView textPrice;
TextView textCategory;
TextView textQuantity;
Button btnEdit;
Button btnDelete;
}
}

用户.java

public class User {
String name;
String price;
String category;
String quantity;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPrice() {
return price;
}
public void setPrice(String price) {
this.price = price;
}
public String getCategory() {
return category;
}
public void setCategory(String category) {
this.category = category;
}
public String getQuantity() {
return quantity;
}
public void setQuantity(String quantity) {
this.quantity = quantity;
}
public User(String name, String price, String category, String quantity) {
super();
this.name = name;
this.price = price;
this.category = category;
this.quantity = quantity;
}
}

Answer 1

希望我已经解决了你的问题，如果你在payBtn onClick方法中循环访问userArray列表并得到总和怎么办？ 像这样：

Button payBtn = (Button)findViewById(R.id.payBtn);
payBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
int total = 0;
for(User u: userArray){
total += (u.getPrice()*u.getQuantity());
}
Toast.makeText(getApplicationContext(), "Total: +total+"€", Toast.LENGTH_SHORT).show();
}
});

Answer 2

yourButton.setOnClickListener(new View.OnClickListener() {
long total=0;
for(User u:userArray){
String priceAsString=u.getPrice();
String priceWithOutCamma=priceAsString.replaceAll(",","");
String priceWithOutSign=priceWithOutCamma.replaceAll("€","");
int price=Integer.valueOf("priceWithOutSign");
int quantity=Integer.valueOf(u.getQuantity());
total+=price*quantity;
}
DecimalFormat format=new DecimalFormat("#,###");
String totalFormatted=format.format(total);
Toast.makeText(getApplicationContext(), "Total: " +totalFormatted+"€", Toast.LENGTH_SHORT).show();
}

Answer 3

所以对于你的设计，正如我在你的代码中看到的，你有一个 arrayList 来保存你所有创建的项。 我会做这样的事情(在你的活动类中创建这个函数(：

public class CartListActivity extends AppCompatActivity {
ListView userList;
UserCustomAdapter userAdapter;
ArrayList<User> userArray = new ArrayList<User>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_cart_list);
Button payBtn = (Button)findViewById(R.id.payBtn);
payBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Toast.makeText(getApplicationContext(), "Total: x€", Toast.LENGTH_SHORT).show();
}
});
/**
* add item in arraylist
*/
userArray.add(new User("Olives verdes", "1,20€", "Aperitius", "0"));
userArray.add(new User("Olives negres", "1,30€", "Aperitius", "0"));
userArray.add(new User("Cogombrets", "1,80€", "Aperitius","0"));
userArray.add(new User("Patates Lay's", "1,19€", "Aperitius","0"));
userArray.add(new User("Potet", "0,95€", "Bebè","0"));
userArray.add(new User("Biberó", "3,85€", "Bebè","0"));
userArray.add(new User("Tovalloletes", "1,10€", "Bebè","0"));
userArray.add(new User("Perxes de nadó", "1,95€", "Bebè","0"));
/**
* set item into adapter
*/
userAdapter = new UserCustomAdapter(CartListActivity.this, R.layout.view_row,
userArray);
userList = (ListView) findViewById(R.id.listView);
userList.setItemsCanFocus(false);
userList.setAdapter(userAdapter);
/**
* get on item click listener
*/
userList.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View v,
final int position, long id) {
Log.i("List View Clicked", "**********");
Toast.makeText(CartListActivity.this,
"List View Clicked:" + position, Toast.LENGTH_LONG)
.show();
}
});
}
private double getTotalPrice(){
double total = 0;
if (userArray.size() == 0){ return total;}
else {
for (User user : userArray ) {
double price = Double.parseDouble(user.getPrice()); // assuming you price is a string , and that you have getters and setters for all of the user's fields
int quantity = Integer.parseInt(user.getQuantity());
total = price*quantity;
}
return total;
}

}

(如果语法有问题，我会编辑我的答案( 然后在您的点击中：

payBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
double totalPrice = getTotalPrice();
String msg = String.format("Total: %f€" , totalPrice ) // %f because the function returns double
Toast.makeText(getApplicationContext(), msg , Toast.LENGTH_SHORT).show();
}
});