[英]JButton doesn't appear until clicked
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出来?
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);
这一切都在同一个 class 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此问题?
程序开始时是空白的,因为您在添加组件之前调用了setVisible
。 添加组件后(在构造函数的末尾)调用setVisible
,它应该可以正常工作。 此外,避免绝对定位和调用 set|Preferred|Minimum|MaximumSize 方法为您的组件。 了解如何使用布局管理器。
编写 GUI.validate(); 将所有组件添加到框架后。 任何时候你添加一些东西到一个框架你必须像这样验证它。 否则,您将得到您所描述的行为。
否。问题是由布局引起的。 在将任何内容添加到 JFrame 或 JPanel 之前,您希望它具有绝对位置,您必须 setLayout(null)。 否则,您将一直有意想不到的行为。 经过三个小时的实验,我自己才弄明白了; 突然间,我将您的帖子与其他不同的主题联系起来,并且奏效了,但这在 Internet 上还没有得到很好的解释。
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