firebase 数据库总价值

Question

在firebase中添加qty值的总量需要什么样的方法？ 这里我附上了firebase数据库截图。

假设列表中的数量和第二个数量之和为 500+800=1300。所以我希望得到总和 1300。下面是从 firebase 检索数据以存储在 textview (@+id/txt_total_value) 上以供显示的代码。

mUploads = new ArrayList<>();

    mDatabaseRef = FirebaseDatabase.getInstance().getReference("Sreeauto");

    mDatabaseRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
                int sum = 0;

            for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
                for (DataSnapshot dSnapshot : postSnapshot.getChildren()) {
                    Datastore upload = dSnapshot.getValue(Datastore.class);
                    mUploads.add(upload);

                    int value = 
Integer.parseInt(dSnapshot.child("qty").getValue(String.class));
                    sum += value;


                }

            }

            mAdapter = new Adapater(ViewProduction.this, mUploads);

            mRecyclerView.setAdapter(mAdapter);
            mprogress.setVisibility(View.INVISIBLE);

            txt_total_value.setText(sum);

        }

Datastore.java

public class Datastore {

private String Date;
private String Shift;
private String Qty;
private String Incharge;

public Datastore(){

}

public Datastore(String date,String shift, String qty, String incharge){
    Date = date;
    Shift = shift;
    Qty = qty;
    Incharge = incharge;
}

public String getDate() {
    return Date;
}

public void setDate(String date) {
    Date = date;
}

public String getShift() {
    return Shift;
}

public void setShift(String shift) {
    Shift = shift;
}

public String getQty() {
    return Qty;
}

public void setQty(String qty) {
    Qty = qty;
}

public String getIncharge() {
    return Incharge;
}

public void setIncharge(String incharge) {
    Incharge = incharge;
}
}

ViewProduction.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.udayaj.sreeauto.ViewProduction">



<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentStart="true"
    android:layout_alignParentTop="true"
    android:layout_marginStart="15dp"
    android:text="Date"
    android:textStyle="bold"
    android:textSize="20sp"
    android:id="@+id/textView2" />

<TextView
    android:id="@+id/textView4"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentTop="true"
    android:layout_marginEnd="16dp"
    android:layout_toStartOf="@+id/incharge"
    android:text="Shift"
    android:textSize="20sp"
    android:textStyle="bold" />

<TextView
    android:id="@+id/textView3"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentEnd="true"
    android:layout_alignParentTop="true"
    android:layout_marginEnd="30dp"
    android:text="Qty"
    android:textSize="20sp"
    android:textStyle="bold" />

<TextView
    android:id="@+id/incharge"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentTop="true"
    android:layout_alignStart="@+id/progress"
    android:layout_marginStart="27dp"
    android:text="Incharge"
    android:textSize="20sp"
    android:textStyle="bold" />


<ProgressBar
    android:id="@+id/progress"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerInParent="true"/>

<android.support.v7.widget.RecyclerView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_below="@+id/incharge"
    android:id="@+id/recyclerji">

</android.support.v7.widget.RecyclerView>

<TextView
    android:id="@+id/txt_total"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_toStartOf="@+id/txt_total_value"
    android:text="Total : "
    android:textSize="20sp"
    android:textStyle="bold" />

<TextView
    android:id="@+id/txt_total_value"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_alignStart="@+id/textView3"
    android:text="00000"
    android:textSize="20sp" />




</RelativeLayout>

举个例子会很有帮助。谢谢。

Answer 1

您似乎已经在循环数据，所以仍然需要提取值并将它们相加：

mDatabaseRef.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        int sum = 0;

        for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
            for (DataSnapshot dSnapshot : postSnapshot.getChildren()) {
                Datastore upload = dSnapshot.getValue(Datastore.class);
                mUploads.add(upload);

                int value = Integer.parseInt(dSnapshot.child("qty").getValue(String.class));
                sum += value;
            }
        }

        System.out.println(sum);
    }

您的Datastore 类中可能已经有qty。但是由于您没有共享该代码，因此上述内容不依赖于此。

考虑将qty 的值存储为数字。这将使Integer.parseInt 变得不必要并减少出现问题的机会。