Question

我已设法使用以下代码检索火力基础数据。然而，我想对我刚刚提取的记录做更多的事情。具体而言我想要总和，因为它们是数值..

public void onDataChange(DataSnapshot snapshot) {
    for (DataSnapshot postSnapshot : snapshot.getChildren()) {
        //Getting the data from snapshot
        DogExpenditure dogExpenditure = postSnapshot.getValue(DogExpenditure.class);

        //Adding it to a string


        String amount = "Amount: "+dogExpenditure.getAmount();


        expenseList.add(expenses);

            if (expenseList.size() == 1) {
                adapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, expenseList);
                listview.setAdapter(adapter);
            } else if (expenseList.size() > 1) {

            }
            System.out.println(expenses);
            listview.setAdapter(adapter);
        }

我的数据库看起来像

所以有可能计算两个金额的总和？我的DogExpenditure类是：

**public class DogExpenditure {
    private String amount;
    private String item;

    public String getAmount() {
        return amount;
    }

    public void setAmount(String amount) {
        this.amount = amount;
    }

    public String getItem() {
        return item;
    }

    public void setItem(String item) {
        this.item = item;
    }
}**

Answer 1

在您的活动中将amount（int）声明为全局int变量，并将其初始化为零并替换 String amount =“Amount：”+ dogExpenditure.getAmount（）; 同量+ =量+ dogExpenditure.getAmount（）; 如果这没有帮助，请通知我

Answer 2

使用此类而不是上述类

公共课DogExpenditure {

private int  amount;
private String item;

public int getAmount() {
    return amount;
}
public String getItem() {
    return item;
}

public void setItem(String item) {
    this.item = item;
}

public void setAmount(int amount) {
    this.amount = amount;
}

}

public void onDataChange（DataSnapshot snapshot）{

for (DataSnapshot postSnapshot : snapshot.getChildren()) {

    //Getting the data from snapshot

    DogExpenditure dogExpenditure=postSnapshot.getValue(DogExpenditure.class);

    //Adding it to a string

    amount+=amount+dogExpenditure.getAmount();



    expenseList.add(expenses);

        if (expenseList.size() == 1) {
            adapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, expenseList);
            listview.setAdapter(adapter);
        } else if (expenseList.size() > 1) {

        }
        System.out.println(expenses);
        listview.setAdapter(adapter);
    }
public String getItem() {
    return item;
}

public void setItem(String item) {
    this.item = item;
}

} **

也不要忘记在活动开始时将金额初始化为0，并在通过类将数值上传到数据库时确保它们是int。这有帮助??

计算数字firebase记录的总和

2 个答案: