Java FX文本框无法正常工作

Question

该程序假设将程序中的值存储到按下写入时。 然后，当按下读取时，它将读取并显示值。 结果应该显示在文本区域中。 但是，运行程序时按钮不会显示。 当我运行它时，java开始在我的计算机上运行，​​但什么都没有出现。

 package program;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Arrays;
import java.util.Date;

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TextArea;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;


public class program extends Application {

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

        @Override
        public void start(Stage primaryStage) throws ClassNotFoundException, IOException {

            // Text area
            TextArea textArea = new TextArea();
            textArea.setStyle("-fx-background-color: lightgrey; -fx-text-fill: blue; -fx-control-inner-background: grey");
            textArea.setPadding(new Insets(15, 15, 15, 15));


            Button write = new Button("Write");
            write.setOnAction(e -> {
                // Create an output stream for file
                try(ObjectOutputStream output = new ObjectOutputStream(new FileOutputStream("Exercise17_05.dat", true))) {
                    int[] numbers = {1, 2, 3, 4, 5};
                    // Write to file
                    // 1. Write double
                    output.writeDouble(5.5);
                    // 2. Write int array object
                    output.writeObject(numbers);
                    // 3. Write date object
                    output.writeObject(new java.util.Date());
                    // 4. Write utf string
                    output.writeUTF("Exercise17_05.dat");

                } catch(IOException exception) {
                    System.exit(0);
                }
            });



            Button read = new Button("Read");
            read.setOnAction(e -> {

                //Create an input stream for file
                try(ObjectInputStream input = new ObjectInputStream(new FileInputStream("Exercise17_05.dat"));){
                // Read from file
                   // 1. Read double
                 double doubleValue = input.readDouble();
                 textArea.appendText("Double value: " + doubleValue);
                 // 2. Read int array object
                 int[] newNumbers = (int[]) (input.readObject());
                 textArea.appendText("Integers: " + Arrays.toString(newNumbers));
                 // 3. Read date object
                 Date date = (java.util.Date) (input.readObject());
                 textArea.appendText("DateTime: " + date);
                 // 4. Read utf string
                 String fileName = input.readUTF();      
                textArea.appendText("File name: " + fileName);

                  } catch(IOException | ClassNotFoundException exception) {
                        System.exit(0);
                    }});


            HBox hButtons = new HBox(read, write);
            VBox vProgram = new VBox(8);
            vProgram.getChildren().addAll(hButtons, textArea);

            primaryStage.setScene(new Scene(vProgram));
            primaryStage.setTitle("Write and Read");
            primaryStage.show();


        }   
}

Answer 1

在代码的末尾添加这两行代码，以使您的gui可见

        primaryStage.setScene(new Scene(vProgram, 300, 250));
        primaryStage.show();