如何从URL读取数据并在折线图中使用它？ 收到JAVAFX错误

Question

I have created an application which reads the price of bitcoin from an online API on IntelliJ using java and javafx. The compiler does not identify any errors, no errors in the fxml file either, but when I run the application, I get multiple javafx errors. How can I fix it? I tried different methods but it seems that something is disconnected in the fxml file. It also seems that the error is coming from my loadChart() method, because when I remove it, all is working smoothly. How could enter code here I link the yValue to the price from the API without errors? Could you please help?

Thank you.

Main class:

package sample;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class Main extends Application {

@Override
public void start(Stage primaryStage) throws Exception{
    Parent root = FXMLLoader.load(getClass().getResource("sample.fxml"));
    primaryStage.setTitle("Bitcoin Tracker");
    primaryStage.setScene(new Scene(root, 600, 600));
    primaryStage.show();
}


public static void main(String[] args) {
    launch(args);
 }
}

Controller class:

package sample;

import javafx.application.Platform;
import javafx.fxml.FXML;
import javafx.fxml.*;
import javafx.scene.Scene;
import javafx.scene.chart.LineChart;
import javafx.scene.chart.XYChart;
import javafx.scene.control.Label;
import javafx.util.*;
import java.util.Calendar;
import java.util.Date;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import javafx.stage.*;
import javafx.application.Application;

public class Controller {

BTC my_price;
@FXML // fx:id="price_label";
        Label price_label;


High  highprice;
@FXML // fx:id="high_label";
     Label high_label;


Low lowprice;
@FXML // fx:id="low_price"
        Label low_label;

VolumeFrom vfrom;
@FXML // fx:id="vfrom_label"
        Label vfrom_label;

VolumeTo vto;
@FXML // fx:id="vto_label"
        Label vto_label;

@FXML // fx:id="chart";
        LineChart<String, Number> line_chart;

ScheduledExecutorService exec = Executors.newScheduledThreadPool(1);

public Controller(){
    my_price = new BTC();

    highprice = new High();

    lowprice = new Low();

    vfrom = new VolumeFrom();

    vto = new VolumeTo();

    Controller ctrl = this;
    exec.scheduleAtFixedRate(new Runnable() {
        @Override
        public void run() {
            ctrl.refreshCurrency();
        }
    }, 1, 1, TimeUnit.MINUTES);
}

public void refreshCurrency() {
    System.out.println("Refreshing...");

    CompletableFuture<Double> future = new CompletableFuture<Double>();

    future.supplyAsync(() -> {
        my_price.getCurrency();
        Platform.runLater(() -> {
            price_label.setText(new Double(my_price.price).toString());
        });

        return 1.0;
    });


    future.supplyAsync(() -> {
        highprice.getHigh();
        Platform.runLater(() -> {
            high_label.setText(new Double(highprice.highprice).toString());
        });

        return 1.0;
    });

    future.supplyAsync(() -> {
        lowprice.getLow();
        Platform.runLater(() -> {
            low_label.setText(new Double(lowprice.lowprice).toString());
        });

        return 1.0;
    });

    future.supplyAsync(() -> {
        vfrom.getVfrom();
        Platform.runLater(() -> {
            vfrom_label.setText(new Double(vfrom.vfrom).toString());
        });

        return 1.0;
    });

    future.supplyAsync(() -> {
        vto.getVto();
        Platform.runLater(() -> {
            vto_label.setText(new Double(vto.vto).toString());
        });

        return 1.0;
    });

    System.out.println("Refreshing high...");
}

public void loadChart(){

    line_chart.setTitle("BTC");

    XYChart.Series series = new XYChart.Series();

double BTCprice = Double.parseDouble(BTC.readFromAPI());

    Calendar c = Calendar.getInstance();
    Date start = new Date(1521171240000L);
    System.out.println(start);

    series.getData().add(new XYChart.Data<>(c.getTime().toString(),(BTCprice)*1000));
    c.add(Calendar.HOUR_OF_DAY, 1);


    line_chart.getData().add(series);
    line_chart.getXAxis().setLabel("Time");
    line_chart.getXAxis().setLabel("Price");

}

}

BTC class:

 package sample;

 import com.google.gson.Gson;
 import com.google.gson.JsonArray;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;

 import java.io.BufferedReader;
 import java.io.InputStreamReader;
  import java.net.URL;

public class BTC {

 double price;

private static String url = "https://min-api.cryptocompare.com/data/histominute?aggregate=0&e=CCCAGG&extraParams=CryptoCompare&fsym=BTC&limit=100&tryConversion=false&tsym=USD";

public static String readFromAPI(){
    String contents = "";
    try {
        URL address = new URL(url);
        InputStreamReader reader = new 
InputStreamReader(address.openStream());
        BufferedReader buffer = new BufferedReader(reader);

        String line = "";
        while ((line = buffer.readLine()) != null) {
            if (line.isEmpty()) {
                break;
            }
            contents += line;
        }
    }catch(Exception e){
        e.printStackTrace();
    }
    return contents;
}

public void getCurrency(){
    try {
        String from_api = readFromAPI();
        Gson gson = new Gson();

        JsonObject response = gson.fromJson(from_api, JsonObject.class);
        JsonArray data = response.getAsJsonArray("Data");

        for(JsonElement item : data ){
            JsonObject item_as_hashmap = item.getAsJsonObject();
            this.price = item_as_hashmap.get("close").getAsDouble();
        }

    }catch(Exception exc){
        exc.printStackTrace();
    }
   }
  }

FXML file:

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.chart.*?>
<?import javafx.scene.text.*?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<?import javafx.geometry.Insets?>
<?import javafx.scene.layout.GridPane?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>

<GridPane alignment="center" hgap="10" vgap="10" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="sample.Controller">
   <columnConstraints>
      <ColumnConstraints />
   </columnConstraints>
   <rowConstraints>
      <RowConstraints />
   </rowConstraints>
   <children>
      <Pane onMouseClicked="#refreshCurrency" prefHeight="472.0" prefWidth="626.0">
         <children>
            <Label layoutX="213.0" layoutY="22.0" text="Bitcoin Tracker">
               <font>
                  <Font name="System Bold" size="24.0" />
               </font>
            </Label>
            <Label layoutX="34.0" layoutY="24.0" text="BTC">
               <font>
                  <Font size="22.0" />
               </font>
            </Label>
            <Label fx:id="price_label" layoutX="95.0" layoutY="25.0" onMouseClicked="#refreshCurrency" text="Label">
               <font>
                  <Font size="21.0" />
               </font>
            </Label>
            <Label layoutX="39.0" layoutY="84.0" text="Volume from:" />
            <Label layoutX="39.0" layoutY="114.0" text="Volume to:" />
            <Label fx:id="vfrom_label" layoutX="119.0" layoutY="84.0" onMouseClicked="#refreshCurrency" text="Label" />
            <Label fx:id="vto_label" layoutX="119.0" layoutY="114.0" onMouseClicked="#refreshCurrency" text="Label" />
            <Label layoutX="479.0" layoutY="84.0" text="High" />
            <Label layoutX="479.0" layoutY="114.0" text="Low" />

            <Label fx:id="high_label" layoutX="526.0" layoutY="84.0" text="Label" />
            <Label fx:id="low_label" layoutX="526.0" layoutY="114.0" onMouseClicked="#refreshCurrency" text="Label" />
            <LineChart fx:id="line_chart" layoutX="40.0" layoutY="171.0" onMouseClicked="#loadChart" prefHeight="273.0" prefWidth="582.0">
              <xAxis>
                <CategoryAxis side="BOTTOM" />
              </xAxis>
              <yAxis>
                <NumberAxis prefHeight="232.0" prefWidth="25.0" side="LEFT" />
              </yAxis>
            </LineChart>
         </children>
      </Pane>
   </children>
</GridPane>

Once I run the main class, and the pane opens, I click once, and then get the following errors:

Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
    at javafx.fxml/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1787)
    at javafx.fxml/javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1670)
    at javafx.base/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
    at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at javafx.base/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at javafx.base/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
    at javafx.base/javafx.event.Event.fireEvent(Event.java:198)
    at javafx.graphics/javafx.scene.Scene$ClickGenerator.postProcess(Scene.java:3589)
    at javafx.graphics/javafx.scene.Scene$ClickGenerator.access$8300(Scene.java:3517)
    at javafx.graphics/javafx.scene.Scene$MouseHandler.process(Scene.java:3885)
    at javafx.graphics/javafx.scene.Scene$MouseHandler.access$1300(Scene.java:3604)
    at javafx.graphics/javafx.scene.Scene.processMouseEvent(Scene.java:1874)
    at javafx.graphics/javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2613)
    at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:397)
    at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
    at java.base/java.security.AccessController.doPrivileged(Native Method)
    at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(GlassViewEventHandler.java:434)
    at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
    at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:433)
    at javafx.graphics/com.sun.glass.ui.View.handleMouseEvent(View.java:556)
    at javafx.graphics/com.sun.glass.ui.View.notifyMouse(View.java:942)
    at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:175)
    at java.base/java.lang.Thread.run(Thread.java:844)
Caused by: java.lang.reflect.InvocationTargetException
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:564)
    at com.sun.javafx.reflect.Trampoline.invoke(MethodUtil.java:76)
    at jdk.internal.reflect.GeneratedMethodAccessor2.invoke(Unknown Source)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:564)
    at javafx.base/com.sun.javafx.reflect.MethodUtil.invoke(MethodUtil.java:275)
    at javafx.fxml/com.sun.javafx.fxml.MethodHelper.invoke(MethodHelper.java:83)
    at javafx.fxml/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1784)
    ... 31 more

Answer 1

要使用HTTPS调用api，请使用HTTP客户端（例如apache http客户端https://hc.apache.org/）