Threadを使ってLabelを更新したい。

Question

threadを使った、カウントダウンタイマーを作成しようとしています。
コマンド画面では、カウントダウンが表示できますが、labelの更新がうまくできません。

lbTime.setText(min+":"+sec);の部分で以下のエラーが出ています。
アドバイス頂ければ幸いです。
よろしくお願い致します。

Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
	at finalProject$MyRunnable.lambda$run$0(finalProject.java:88)
	at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$9(PlatformImpl.java:418)
	at java.base/java.security.AccessController.doPrivileged(Native Method)
	at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:417)
	at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)

Threadのコードになります。

public class MyRunnable implements Runnable
	{
		@Override
		public void run()
		{
			while(true)
			{
				s = timeleft - counter;
				min = s / 60;
				sec = s % 60;
				System.out.println(min+":"+sec);
				Platform.runLater(
	                  () -> lbTime.setText(min+":"+sec));
				try{
					Thread.sleep(1000);
					counter++;
				}catch(InterruptedException e)
				{
					System.out.println(e);
				}
			}
		}
	}

全体のコード

import javafx.application.*;
import javafx.scene.*;
import javafx.scene.layout.*;
import javafx.scene.control.*;
import javafx.scene.paint.*;
import javafx.scene.image.*;
import javafx.scene.effect.*;
import javafx.scene.text.*;
import javafx.scene.input.*;
import javafx.scene.canvas.*;
import javafx.scene.shape.*;
import javafx.stage.*;
import javafx.event.*;
import javafx.geometry.*;
import javafx.collections.*;
import java.util.*;

public class finalProject extends Application
{
	private int counter;
	private int timeleft;
	private Label lbTime;
	private int s;
	private int min;
	private int sec;
	private MyRunnable runnable;
	private Thread thread;

	public void start(Stage stage) throws Exception
	{
		timeleft = 65;

		ImageView icon1 = new ImageView("setting.png");

		Label[] lbs = new Label[2];
		lbs[0] = new Label();
		lbs[1] = new Label("進捗状況");
		lbs[0].setGraphic(icon1);

		Label lbTasks = new Label("Tasks");
		Label lbTime = new Label("00:00");

		Button btPlay = new Button("PLAY");
		Button btReset  = new Button("RESET");
		btPlay.setGraphic(new ImageView("play.png"));
		btPlay.setId("play");
		btReset.setGraphic(new ImageView("reset.png"));
		btReset.setId("reset");

		ButtonEventHandler bh = new ButtonEventHandler();
		btPlay.addEventHandler(ActionEvent.ANY, bh);
		btReset.addEventHandler(ActionEvent.ANY, bh);

		runnable = new MyRunnable();
		thread = new Thread(runnable);

		GridPane gp = new GridPane();
		gp.add(btPlay, 0, 0);
		gp.add(btReset, 1, 0);
		gp.setBackground(null);

		VBox vb = new VBox();
		ObservableList<Node> lst = vb.getChildren();
		lst.addAll(lbs);
		lst.add(lbTime);
		lst.addAll(gp);
		lst.add(lbTasks);

		Scene scene = new Scene(vb, 500, 500);
		scene.setFill(Color.LIGHTGRAY);

		stage.setScene(scene);
		stage.setTitle("Pomodoro");
		stage.setResizable(false);

		stage.show();
	}

	public class MyRunnable implements Runnable
	{
		@Override
		public void run()
		{
			while(true)
			{
				s = timeleft - counter;
				min = s / 60;
				sec = s % 60;
				System.out.println(min+":"+sec);
				Platform.runLater(
	                  () -> lbTime.setText(min+":"+sec));
				try{
					Thread.sleep(1000);
					counter++;
				}catch(InterruptedException e)
				{
					System.out.println(e);
				}
			}
		}
	}

	private class ButtonEventHandler implements EventHandler<ActionEvent>
	{
		public void handle(ActionEvent e)
		{
			Button bt = (Button)e.getTarget();
			String id = bt.getId();
			if(id.equals("play")){
				thread.start();
			}
			if(id.equals("reset")){

			}
		}
	}

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

Answer 1

以下のコードで解決できました。

public class MyRunnable implements Runnable
{
public void run()
{
while(true)
{
s = timeleft - counter;
min = s / 60;
sec = s % 60;
System.out.println(String.format("%01d:+sec"));
Platform.runLater(
() -> lbTime.setText(min+":"+sec));
try{
Thread.sleep(1000);
counter++;
}catch(InterruptedException e)
{
System.out.println(e);
}
}
}
}