Javafx - chamando função por tempos determinados

import javafx.application.Application;

import javafx.collections.ObservableList;

import javafx.concurrent.Task;

import javafx.scene.Group;

import javafx.scene.Node;

import javafx.scene.Scene;

import javafx.scene.paint.Color;

import javafx.scene.text.Font;

import javafx.scene.text.FontWeight;

import javafx.stage.Stage;

import javafx.scene.canvas.Canvas;

import javafx.scene.canvas.GraphicsContext;

import javafx.scene.layout.Pane;

public class PROJETO extends Application {

     static String str      = "";

     static String str_2;

     static Stage  stage;

     Scene              scene;

     static Pane        root = new Pane ( );

     static Canvas canvas = new Canvas ( 660, 460 );

     static GraphicsContext ctx = canvas.getGraphicsContext2D ( );

     //Chamando uma função depois de um certo tempo

     //Chamada Sleep ( 1800, k );

     public static Node Teste_3 ( ) {

         Group y = new Group ( );

         ctx.setFill ( Color.RED );

         ctx.fillText ( "MUITO OBRIGADO", 280, 420 );

         return y;

     }

     public static Node Teste_2 ( ) {

         Group y = new Group ( );

         ctx.setFill ( Color.BLUE );

         ctx.fillText ( "Por: Samuel Lima", 225, 150 );

         return y;

     }

     public static Node Teste_1 ( ) {

         Group y = new Group ( );

         ctx.setFill ( Color.BLACK );

         ctx.fillText ( "Veja abaixo as chamadas temporizadas", 200, 100 );

         return y;

     }

     public static int Sleep ( int x, int k ){

         Task < Integer > close = new Task < Integer > ( ) {

              @Override

              protected Integer call ( ) throws Exception {

                   Thread.sleep ( x );

                   return null;

              }

         };       

         close.setOnSucceeded ( c -> {

              if ( k == 1 )

                   Teste_1 ( );

              if ( k == 2 )

                   Teste_2 ( );

              if ( k == 3 )

                   Teste_3 ( );

         } );

         new Thread ( close ).start ( );

         return 0;

     }

     // //////////////////////////////////////////////////////////////////////////

     @Override

     public void start ( Stage stage ) {

         ctx.setLineWidth ( 22.0 );

         ctx.strokeRoundRect ( 10, 10, 640, 440, 10, 10 );

         root.getChildren ( ).add ( canvas );

         Scene scene = new Scene ( root );

         stage.setTitle ( "CHAMANDO FUNÇÃO EM TEMPOS DETERMINADOS" );

         ctx.setFont ( Font.font ( "Arial", FontWeight.BOLD, 15 ) );

         ctx.setFill ( Color.RED );

         ctx.fillText ( "CHAMANDO FUNÇÃO EM TEMPOS DETERMINADOS", 150, 60 );

         ObservableList < Node > content = ( ( Pane ) scene.getRoot ( ) )

                   .getChildren ( );

         stage.setScene ( scene );

         stage.show ( );

         content.add ( Tempo ( ) );

     }

     // //////////////////////////////////////////////////////////////////////////

     public static Node Tempo ( ) {

         Group y = new Group ( );

         int k = 1;

         Sleep ( 1800, k );

         k = 2;

         Sleep ( 2800, k );

         k = 3;

         Sleep ( 3800, k );

         return y;

     }

     // //////////////////////////////////////////////////////////////////////////

     public static void main ( String [ ] args ) {

         Application.launch ( args );

     }

}