Question

我知道其他线程已经问过这个问题，但我看不出我的代码有什么问题。我的JPanel没有出现在我的JFrame中。请协助。

这是一个入门级的计算机科学学校作业，所以一些其他愚蠢的事情是我无法控制的。

感谢。

package view;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class DequeueView {

    //main JFrame
    private JFrame mainFrame ;

    //Containers
    private JPanel display;
    private JPanel buttons;

    //Buttons
    private JButton addFront;
    private JButton dequeue;
    private JButton enqueue;
    private JButton removeRear;

    //Textbox and label
    private JTextField displayQueue;
    private JLabel greeting;

    /**
     * Constructor for the main application with the title bar set to 
     * a title.  
     */
    public DequeueView(){

        /*
         * The hierarchy is as follows:
         * 
         * Container JPanel-    to display the message "Hello" and to display queue.
         *      Label , textbox
         * Container JPanel-    to put the buttons. 
         *      JButtons
         */

        JPanelDisplayHelper();      //formats the displays.
        JPanelButtonHelper();       //formats the buttons.
        JFrameHelper();             //formats the JFrame.

    }

    /**
     * Sets up the JFrame that will house the 4 buttons.
     */
    private void JPanelButtonHelper(){

        addFront = new JButton("Add to Front");
        dequeue = new JButton("Take from Front");
        enqueue = new JButton("Add to Back");
        removeRear = new JButton("Take from Back");

        buttons = new JPanel();
        buttons.add(addFront);
        buttons.add(dequeue);
        buttons.add(enqueue);
        buttons.add(removeRear);        
    }

    /**
     * Sets up the JFrame that will house everything. 
     */
    private void JFrameHelper(){

        String title = new String ("Queue Application");

        mainFrame = new JFrame();
        mainFrame.setLocation(200,150);
        mainFrame.setSize(500, 500);
        mainFrame.setResizable(false);
        mainFrame.setTitle(title);
        mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        mainFrame.add(display);
        mainFrame.add(buttons);
        mainFrame.setLayout(new BorderLayout());
        mainFrame.setVisible(true);

    }

    /**
     * Sets up the JPanel that will display the greeting and the queue in 
     * String form. 
     */
    private void JPanelDisplayHelper(){

        String text = new String("Hello, this app displays a queue. Enjoy!");

        //formats the label
        greeting = new JLabel(text, JLabel.LEFT);
        greeting.setVisible(true);


        //formats the JTextField.
        displayQueue = new JTextField(10);
        displayQueue.setText("Your Queue will display here!");
        displayQueue.setBackground(Color.WHITE);
        displayQueue.setEditable(false);
        displayQueue.setVisible(true);
        displayQueue.validate();

        display = new JPanel();
        display.add(greeting);
        display.add(displayQueue);
        display.setLayout(new BorderLayout());


    }

}

Answer 1

你是否已经在这个主方法中实现了类？除非你真正定义它，否则它不会在程序的主方法中知道它

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

PS：你可以在JFrame frame = new JFrame中添加title参数（＆＃34; title＆＃34;）

JFrame不会出现

1 个答案: