java - JButton 直到被点击才出现

Question

对于这个程序，JButton 似乎不会显示，除非您单击应该是 JButton 的区域； JFrame 启动空白。单击按钮的那一刻，相应的代码就会运行，按钮最终会显示出来。

如何让按钮在启动程序时显示？

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

import javax.swing.*;
/*
The Amazing BlackJack Advisory Tool by JoshK,HieuV, and AlvinC.
Prepare to be amazed :O
 */
public class BlckJackUI {
    //main class, will contain the JFrame of the program, as well as all the buttons.
    public static void main(String args[])
    {
    //Creating the JFrame
    JFrame GUI = new JFrame("Blackjack Advisor");
    GUI.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    GUI.setSize(1300, 900);
    GUI.setContentPane(new JLabel(new ImageIcon("C:\\Users\\Hieu Vo\\Desktop\\Green Background.png")));
    GUI.setVisible(true);
    // Because each button needs to run through the Math class.
    final Math math = new Math();
    // The Ace Button:
    ImageIcon Ace = new ImageIcon("/Users/computerscience2/Downloads/Ace.jpg");
    JButton ace = new JButton(Ace);
    ace.setSize(300, 100);
    ace.setLocation(100, 100);
    ace.addActionListener(new ActionListener()
    {
        public void actionPerformed(ActionEvent e)
        {
            //Automatically default the the Ace to 11, and if Bust, Ace becomes 1. 
            if (math.array.playerhandtotal <= 21)
            {
                math.cardvalue = math.cardvalue + 11;
            }
            else
            {
                math.cardvalue = math.cardvalue + 1;
            }
            math.array.clicktracker++;
            math.calcResult();
            JOptionPane.showMessageDialog(null,math.array.result);
        }
    });
    GUI.add(ace);
    ImageIcon Two = new ImageIcon("/Users/computerscience2/Downloads/2.jpg");
    JButton two = new JButton(Two);
    two.setSize(300, 100);
    two.setLocation(100, 200);
    two.addActionListener(new ActionListener ()
    {
        public void actionPerformed(ActionEvent e)
        {
            /*
                This generally repeats throughout the whole class, and the only
                thing different is the changing cardvalue. When a button is pressed,
                respective cardvalues are added into the playerhand ArrayList, and
                totaled up to form playerhandtotal, which is a major factor in 
                bringing up the advice.
             */
            math.cardvalue = math.cardvalue + 2;
            math.array.clicktracker++;
            math.calcResult();
            JOptionPane.showMessageDialog(null,math.array.result);
        }
    });
    GUI.add(two);

等等，等等...只是一堆相同的东西，更多按钮的编码方式与 JButton 2 完全相同，但关联的值不同。

    JButton start = new JButton("Start/Reset");
    start.setSize(300, 100);
    start.setLocation(500,500);
    start.addActionListener(new ActionListener ()
    {
        public void actionPerformed(ActionEvent e)
        {
            /*
            The start button also acts like a reset button, and the concept is fairly
            simple. If we reset all the important values to 0 or "null," then the 
            program acts as if it was just opened.
             */
            Arrays array = new Arrays();
            array.playerhand.clear();
            array.dealer = 0;
            math.array.starttracker++;
            math.array.clicktracker = 0;
            array.playerhandtotal = 0;
            math.cardvalue = 0;
            array.result = null;
            JOptionPane.showMessageDialog(null,"Please select the card \nthat the dealer is showing :)");

        }
    });
    GUI.add(start);
    GUI.setLayout(null);

这都在同一个类中，我知道布局会更好，但也许有一种方法可以使用我现在拥有的解决这个问题？

Answer 1

程序一开始是空白的，因为您在添加组件之前调用了 setVisible。添加组件(在构造函数的末尾)后调用 setVisible，它应该可以正常工作。此外，避免绝对定位和调用组件的 set|Preferred|Minimum|MaximumSize 方法。了解如何使用布局管理器。