在安卓折线图的 xAxis 中显示日期

Question

我正在尝试在两个不同的折线图中显示我从 Firestore 集合文档中检索到的一些值。我使用 jjoe64 库，但当我按下按钮生成图形时，我的应用程序崩溃了。Firestore 数据库 这是我的片段代码：

package com.example.drodo.diamondbeacons;

import android.content.Context;
import android.graphics.Color;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.inputmethod.InputMethodManager;
import android.widget.Button;
import android.widget.EditText;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.firestore.DocumentSnapshot;
import com.google.firebase.firestore.FirebaseFirestore;
import com.google.firebase.firestore.QuerySnapshot;
import com.jjoe64.graphview.GraphView;
import com.jjoe64.graphview.LegendRenderer;
import com.jjoe64.graphview.Viewport;
import com.jjoe64.graphview.helper.StaticLabelsFormatter;
import com.jjoe64.graphview.series.DataPoint;
import com.jjoe64.graphview.series.LineGraphSeries;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

/**
* A simple {@link Fragment} subclass.
*/
public class TimelineFragment extends Fragment {
private FirebaseFirestore firebaseFirestore;
private FirebaseAuth firebaseAuth;
private EditText regionText;
private Button regionChooseBtn;

public TimelineFragment() {
// Required empty public constructor
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_timeline, container, false);
regionText = (EditText) view.findViewById(R.id.selectRegionText);
regionChooseBtn = (Button) view.findViewById(R.id.chooseRegionBtn);
firebaseAuth = FirebaseAuth.getInstance();
firebaseFirestore = FirebaseFirestore.getInstance();
regionChooseBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String select_text = regionText.getText().toString();
if (!select_text.isEmpty()) {
if(firebaseAuth.getCurrentUser() != null) {
firebaseFirestore.collection("PuckData").whereEqualTo("region", select_text)
.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
@Override
public void onComplete(@NonNull Task<QuerySnapshot> task) {
if (task.isSuccessful()) {
List<String> dates_list = new ArrayList<>();
List<Integer> temperature_list = new ArrayList<>();
List<Integer> light_list = new ArrayList<>();
for (DocumentSnapshot document : task.getResult()) {
int light = document.getLong("light").intValue();
int temperature = document.getLong("temperature").intValue();
Date date = document.getDate("timestamp");
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("dd/MM/yy-HH:mm");
String stringDate = simpleDateFormat.format(date);
temperature_list.add(temperature);
light_list.add(light);
dates_list.add(stringDate);
}
GraphView graph = view.findViewById(R.id.graph);
LineGraphSeries<DataPoint> series = new LineGraphSeries<>(generateLightList(dates_list, light_list));
graph.addSeries(series);
Log.d("LIST", "DATES: " + dates_list.toString());
Log.d("LIST", "TEMPS: " + temperature_list.toString());
Log.d("LIST", "LIGHTS: " + light_list.toString());
} else {
Log.d("PUCK", "Error getting documents: ", task.getException());
}
}
});
}
}
regionText.setText("");
final InputMethodManager imm = (InputMethodManager) getActivity().getSystemService(Context.INPUT_METHOD_SERVICE);
imm.hideSoftInputFromWindow(getView().getWindowToken(), 0);
}
});
return view;
}
private DataPoint[] generateLightList(List<String> dateList, List<Integer> lightList) {
DataPoint[] values = new DataPoint[dateList.size()];
for (int i = 0; i < dateList.size(); i++) {
DataPoint v = new DataPoint(Double.parseDouble(dateList.get(i)), lightList.get(i));
values[i] = v;
}
return values;
}
private DataPoint[] generateTemperatureList(List<String> dateList, List<Integer> temperatureList) {
DataPoint[] values = new DataPoint[dateList.size()];
for (int i = 0; i < dateList.size(); i++) {
DataPoint v = new DataPoint(Double.parseDouble(dateList.get(i)), temperatureList.get(i));
values[i] = v;
}
return values;
}
}

这是我的模型 PuckData 类：

package com.example.drodo.diamondbeacons.model;
import com.google.firebase.firestore.ServerTimestamp;
import java.util.Date;
/**
* Created by drodo on 25-Mar-18.
*/
public class PuckData {
public int light, temperature;
public double battery;
public Date timestamp;

public PuckData() {}
public PuckData(int light, int temperature, double battery, Date timestamp) {
this.light = light;
this.temperature = temperature;
this.battery = battery;
this.timestamp = timestamp;
}
public double getLight() {
return light;
}
public void setLight(int light) {
this.light = light;
}
public double getTemperature() {
return temperature;
}
public void setTemperature(int temperature) {
this.temperature = temperature;
}
public double getBattery() {
return battery;
}
public void setBattery(double battery) {
this.battery = battery;
}
public Date getTimestamp() {
return timestamp;
}
public void setTimestamp(Date timestamp) {
this.timestamp = timestamp;
}
}

我想在第一个图表中显示xAxis(日期(和yAxis(光(以及另一个图表中的日期温度。当我按下按钮以仅选择用户在编辑文本中键入的区域时，我的应用程序崩溃了，这就是我得到的：

java.lang.NumberFormatException：对于输入字符串："07/07/18-04：50" at java.lang.FloatingDecimal.readJavaFormatString(FloatingDecimal.java：1306( at java.lang.Double.parseDouble(Double.java：547( at com.example.drodo.diamondbeacons.TimelineFragment.generateLightList(TimelineFragment.java：118(

Answer 1

错误消息非常清楚。您正在调用Double.parseDouble(dateList.get(i))，但dateList.get(i)不是数字，而是一串格式"07/07/18-04:50"。

我的猜测是你正在尝试调用这个DataPoint的构造函数：public DataPoint(Date x, double y) {...，这意味着你应该将字符串解析为其相应的数据。

Date date=new SimpleDateFormat("dd/MM/yyyy-HH:mm").parse(dateList.get(i));
DataPoint v = new DataPoint(date, lightList.get(i));