package application;   import java.io.File; import org.james.component.ButtonBox;import org.james.component.FileReceiverGrid;import org.james.component.FileSenderGrid;import javafx.application.Application;import javafx.event.ActionEvent;import javafx.event.EventHandler;import javafx.scene.Scene;import javafx.scene.layout.BorderPane;import javafx.stage.FileChooser;import javafx.stage.Stage;  public class Main extends Application {     public static Stage primaryStage;     @Override  public void start(Stage primaryStage) {    try {      this.primaryStage = primaryStage;      primaryStage.setFullScreen(false);      primaryStage.setResizable(false);             FileReceiverGrid fileReceiverGrid = new FileReceiverGrid();      fileReceiverGrid.initialize();      FileSenderGrid fileSenderGrid = new FileSenderGrid();      fileSenderGrid.initialize();             ButtonBox buttonBox = new ButtonBox();      buttonBox.initialize();             BorderPane root = new BorderPane();      root.setTop(fileReceiverGrid);      root.setBottom(buttonBox);             buttonBox.getReceiveFileFunc().setOnAction(new EventHandler<ActionEvent>() {        @Override        public void handle(ActionEvent event) {          buttonBox.getReceiveFileFunc().setDisable(true);          buttonBox.getSendFileFunc().setDisable(false);          root.setTop(fileReceiverGrid);        }      });             buttonBox.getSendFileFunc().setOnAction(new EventHandler<ActionEvent>() {        @Override        public void handle(ActionEvent event) {          buttonBox.getReceiveFileFunc().setDisable(false);          buttonBox.getSendFileFunc().setDisable(true);          root.setTop(fileSenderGrid);        }       });             fileSenderGrid.getSelectFileBtn().setOnAction(new EventHandler<ActionEvent>() {        @Override        public void handle(ActionEvent event) {          FileChooser fileChooser = new FileChooser();          fileChooser.setTitle("打開文件");          File selectedFile = fileChooser.showOpenDialog(primaryStage);          if(selectedFile != null){            fileSenderGrid.setFile(selectedFile);            fileSenderGrid.getFileNameLabel().setText(selectedFile.getPath());          }        }       });             Scene scene = new Scene(root,800,400);      scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());      primaryStage.setScene(scene);      primaryStage.show();    } catch(Exception e) {      e.printStackTrace();    }  }        public static void main(String[] args) {    launch(args);  }}