java swing它沒有system.out.println

Question

你好，所以我一周前開始學習 Java，我基本上開始制作 gui 只是為了看看事情是如何工作的，我發現了一個奇怪的“錯誤”，或者我不完全理解事情是如何工作的，它甚至不是一個錯誤

我有一個名為startPanel的類，它使面板從一開始就可見，它會詢問您希望登錄管理員、用戶或訪客的內容，這是 startPanel：

package library;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

/*
 * this panel is responsible for the first opening panel and redirects you to your panel
 * 
 * 
 */
import javax.swing.*;
public class startPanel extends JFrame {


boolean adminState=false;
boolean userState=false;
boolean guestState=false;

JButton adminBut,userBut,guestBut ;

//start of constructor
public startPanel(){
    //frame size,close when pressing x,title,and spawn at middle of the screen
    this.setSize(500,500);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    this.setTitle("Welcome guest");
    this.setLocationRelativeTo(null);
    //making the panel
    JPanel panel1 = new JPanel();
    //making a label to fill things up it doesn't really do anything
    JLabel startLabel = new JLabel("you wan't to log in as...");
    //3 buttons for the user to click 1 only and the according frame will show up
    adminBut = new JButton("Admin");
    userBut = new JButton("User");
    guestBut = new JButton("Guest");
    //making an event handler for admin only so far just for test purposes
     ListenForButton lForButton = new ListenForButton();
     adminBut.addActionListener(lForButton);

     //adding comps to the panel
    panel1.add(startLabel);
    panel1.add(adminBut);
    panel1.add(userBut);
    panel1.add(guestBut);

    //adding the panel to the frame
    this.add(panel1);

} // end of startPanel constructor

private class ListenForButton implements ActionListener {

    @Override
    public void actionPerformed(ActionEvent event) {
        /*probably not the correct way to do what i want to but just figured this might work
         *it only works for admin button if the user presses the adminBut
         *it will change the states and with a getter we can change each state 
         *from main accordingly
         */
        if (event.getSource() == adminBut ){
            adminState=true;
            guestState=false;
            userState= false;

        }
    }

} // end of Listen for button

//all getters for the states
public boolean getAdminState(){
    return adminState;
}
public boolean getUserState(){
    return guestState;
}
public boolean getGuestState(){
    return userState;
}

}

這是主要的：

package library;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.*;

public class mainLibrary {
public static void main(String[] args) {


    adminPanel adminP = new adminPanel();
    userPanel userP = new userPanel();
    startPanel gui = new startPanel();
    gui.setVisible(true);

    while(true){
        System.out.println(gui.getAdminState());
        if (gui.getAdminState() == true) {
            gui.setVisible(false);
            userP.setVisible(true);

        }
    }

現在的問題是，如果我刪除System.out.println(gui.getAdminState()); 這不起作用它甚至不會進入如果在開始時它是假的如果我不刪除它正常工作：/所以發生了什么

如果重要，這是 adminPanel 的 adminPanel

package library;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class adminPanel extends JFrame {

    //start of adminPanel constructor
public adminPanel(){ 
    //frame size,close when pressing x,title,and spawn at middle of the screen
    this.setSize(500,500);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    this.setTitle("Admin panel area");
    this.setLocationRelativeTo(null);

    JPanel panel1 = new JPanel();

    this.add(panel1);


    } //end of admin constructor

}

Answer 1

這不是一個好的 GUI 設計。 永遠不要使用這種主動循環。

備注：使用標准命名約定（大寫/小寫），切勿將框架稱為面板（這太混亂了）。

更好的設計是引用要在 startPanel 中激活的面板並設置適當的屬性以響應按鈕操作。 就像是：

class StartFrame extends JFrame implements ActionListener {
    private JFrame adminFrame;
    private JFrame userFrame;
    ...

    // add construtor to initialize adminFrame and userFrame appropriately
    ...

    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == adminBut) {
            this.setVisible(false);
            adminFrame.setVisible(true);
        }
        if (e.getSource() == userBut) {
            this.setVisible(false);
            userFrame.setVisible(true);
        }
    }
}