使用addValueEventListener从Firebase数据库获取随机数据

Question

如何在Firebase fatabase中创建一个数据库，该数据库使用此代码获取随机数据。我创建了数据库，但是我的应用程序崩溃了。

LogCat在行上显示错误：

  

myInteger = Integer.parseInt（（字符串）

     

dataSnapshot.child（“ the_integer”）。getValue（））;

我确定是因为我的数据库错误。

我的数据库结构是：

import React from 'react';
import PivotTableUI from 'react-pivottable/PivotTableUI';
import 'react-pivottable/pivottable.css';
import TableRenderers from 'react-pivottable/TableRenderers';
import Plot from 'react-plotly.js';
import createPlotlyRenderers from 'react-pivottable/PlotlyRenderers';


// create Plotly renderers via dependency injection
const PlotlyRenderers = createPlotlyRenderers(Plot);



const data1 = [{'Country':'USA','Sales':45000}, 
{'Country':'USA','Sales':50000},{'Country':'CA','Sales':15000}]

const data2 = [{'Product':'Sofa','Sales':5000},{'Product':'Dinner 
Table','Sales':50000},{'Product':'Chair','Sales':15000}]

const dataDic = {'Region':data1,'Products':data2}



class App extends React.Component {


constructor(props) {
  super(props);
  this.state = {selectedOption: 'Region'};
  this.handleChange = this.handleChange.bind(this);
  this.handleSubmit = this.handleSubmit.bind(this);
}

handleChange(event) {
  this.setState({selectedOption: event.target.value});

}


handleSubmit(event) {
  alert('You have selected ' + this.state.selectedOption);
  event.preventDefault();
}


render() { 


    return <div>
              <select defaultValue="Region" onChange={(e)=>   
 this.handleChange(e)}>
                    <option  value="Region">Region</option>
                    <option value="Products">Products</option>
              </select>
              <br/>
              <br/>

              <PivotTableUI
                  data={dataDic[this.state.selectedOption]}
                  onChange={s => this.setState(s)}

           renderers={Object.assign({},TableRenderers)}//,PlotlyRenderers)}
                  {...this.state}
              />

            </div>;
     }
 }



export default App;

我的服务活动是：

 databaseRefrence
    |
    |_______"data"
    |         |
    |         |_______"people"
    |         |
    |         |_______"cities"
    |
    |_______"count"
                |
                |_______"the_integer"
                |
                |_______"my_order_type"

}

LogCat错误：

public class MyService {

private Variables;
private Random random;
Context context;
DatabaseRefrence refrence;
RelativeLayout myLayout;
DatabaseRefrence database;
DatabaseRefrence refrenceSize;
int myInteger;
Button btnLoad;

MyService(Context context, RelativeLayout myLayout, Button btnLoad) {
    this.context = context;
    this.myLayout = myLayout;
    this.btnLoad = btnLoad;
    this.database = FirebaseDatabase.getInstance().getReference().child("data");
    this.refrenceSize = FirebaseDatabase.getInstance().getReference().child("count");
    this.random = new Random();
}

public void showRandom() {
    refrenceSize.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            myInteger = Integer.parseInt((String) dataSnapshot.child("the_integer").getValue());
            refrence = database.child(String.valueOf(random.nextInt(myInteger)));
            refrence.addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(@NonNull final DataSnapshot dataSnapshot) {
                    String order = (String) dataSnapshot.child("my_order_type").getValue();
                    btnLoad.setOnClickListener(new View.OnClickListener() {

                        @Override
                        public void onClick(View view) {
                            if (order.equals(people)) {
                                //Do something
                            } else if (order.equals(cities)) {
                                //Do something
                            }
                        }
                    });
                }

                @Override
                public void onCancelled(@NonNull DatabaseError databaseError) {
                    //Error
                }
            });
        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {
            //Error            
        }
    });
}