Java JProgressbar不更新，未知源錯誤

Question

我正在學習在我自己的程序在Java和我試圖使一個健康欄，健康顯示，但當我按下「向上」按鈕（我我正在製作一個簡單的二維遊戲的骨架，該按鈕只是爲了瞭解命令），健康不會下降。當我按下按鈕3次，這說明了我的CMD：

這裏是我的代碼：

import javax.swing.*; 
import java.awt.*; 
import java.awt.event.*; 

public class test{ 

    private static JFrame frame = new JFrame("test"); 

    private static JPanel panel = new JPanel(); 
    private static JPanel panel1 = new JPanel(); 
    private static JPanel panel2 = new JPanel(); 

    private static JButton button1 = new JButton("UP"); 
    private static JButton button2 = new JButton("DN"); 
    private static JButton button3 = new JButton("L"); 
    private static JButton button4 = new JButton("R"); 

    private static JLabel background = new JLabel(new ImageIcon("C:\\Users\\beau\\Downloads\\background.jpg")); 

    private static int startHealth = 20; 
    private static int healthBoost = 0; 
    private static int maxHealth = startHealth + healthBoost; 
    private static int damage = 0; 
    private static int damageTaken; 
    private static int curentHealth; 


    public static void main(String[] args){ 
     //JFrame Properties 
     frame.setSize(900,600); 
     frame.setLocationRelativeTo(null); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     frame.setResizable(false); 
     frame.setVisible(true); 


     //shown stuff Properties and Adding 
     damageTaken += damage; 
     curentHealth = maxHealth - damageTaken; 

     JProgressBar health = new JProgressBar(0,curentHealth); 
     health.setStringPainted(true); 
     health.setString(curentHealth + "/" + maxHealth); 
     health.setValue(curentHealth); 

     frame.add(background); 

     panel.setLayout(null); 
     background.setLayout(null); 

     button1.setBounds(61,420,50,50); 
     button2.setBounds(61,520,50,50); 
     button3.setBounds(11,470,50,50); 
     button4.setBounds(111,470,50,50); 
     panel.setBounds(725,0,175,600); 
     health.setBounds(10,20,150,20); 

     panel.add(button1); 
     panel.add(button2); 
     panel.add(button3); 
     panel.add(button4); 
     panel.add(health); 
     background.add(panel); 


     button1.addActionListener (new Action1()); 


     background.revalidate(); 
    } 

    static class Action1 implements ActionListener{ 
     public void actionPerformed (ActionEvent e){ 
      damage = 5; 
      main(new String[] {"a","b","c"}); 
     } 
    } 
    static class Action2 implements ActionListener{ 
     public void actionPerformed (ActionEvent e){ 

     } 
    } 
    static class ActionReset implements ActionListener{ 
     public void actionPerformed (ActionEvent e){ 

     } 
    } 
} 
    import javax.swing.*; 
    import java.awt.*; 
    import java.awt.event.*; 

    public class test{ 

    private static JFrame frame = new JFrame("test"); 

    private static JPanel panel = new JPanel(); 
    private static JPanel panel1 = new JPanel(); 
    private static JPanel panel2 = new JPanel(); 

    private static JButton button1 = new JButton("UP"); 
    private static JButton button2 = new JButton("DN"); 
    private static JButton button3 = new JButton("L"); 
    private static JButton button4 = new JButton("R"); 

    private static JLabel background = new JLabel(new ImageIcon("C:\\Users\\beau\\Downloads\\background.jpg")); 

    private static int startHealth = 20; 
    private static int healthBoost = 0; 
    private static int maxHealth = startHealth + healthBoost; 
    private static int damage = 0; 
    private static int damageTaken; 
    private static int curentHealth; 


    public static void main(String[] args){ 
     //JFrame Properties 
     frame.setSize(900,600); 
     frame.setLocationRelativeTo(null); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     frame.setResizable(false); 
     frame.setVisible(true); 


     //shown stuff Properties and Adding 
     damageTaken += damage; 
     curentHealth = maxHealth - damageTaken; 

     JProgressBar health = new JProgressBar(0,curentHealth); 
     health.setStringPainted(true); 
     health.setString(curentHealth + "/" + maxHealth); 
     health.setValue(curentHealth); 

     frame.add(background); 

     panel.setLayout(null); 
     background.setLayout(null); 

     button1.setBounds(61,420,50,50); 
     button2.setBounds(61,520,50,50); 
     button3.setBounds(11,470,50,50); 
     button4.setBounds(111,470,50,50); 
     panel.setBounds(725,0,175,600); 
     health.setBounds(10,20,150,20); 

     panel.add(button1); 
     panel.add(button2); 
     panel.add(button3); 
     panel.add(button4); 
     panel.add(health); 
     background.add(panel); 


     button1.addActionListener (new Action1()); 


     background.revalidate(); 
    } 

    static class Action1 implements ActionListener{ 
     public void actionPerformed (ActionEvent e){ 
      damage = 5; 
      main(new String[] {"a","b","c"}); 
     } 
    } 
    static class Action2 implements ActionListener{ 
     public void actionPerformed (ActionEvent e){ 

     } 
    } 
    static class ActionReset implements ActionListener{ 
     public void actionPerformed (ActionEvent e){ 

     } 
    } 
} 

我搜索谷歌和很多上stackoverflow.com，但我沒有」找到任何看起來像我的問題的問題。有人可以幫助我解決這個問題嗎？

Answer 1

你收到這些異常，如果最大值爲低，則最小值：

new JProgressBar(0,-5); 

看到這個代碼：

/** 
    * Initializes value, extent, minimum and maximum. Adjusting is false. 
    * Throws an <code>IllegalArgumentException</code> if the following 
    * constraints aren't satisfied: 
    * <pre> 
    * min &lt;= value &lt;= value+extent &lt;= max 
    * </pre> 
    */ 
    public DefaultBoundedRangeModel(int value, int extent, int min, int max) 
    { 
     if ((max >= min) && 
      (value >= min) && 
      ((value + extent) >= value) && 
      ((value + extent) <= max)) { 
      this.value = value; 
      this.extent = extent; 
      this.min = min; 
      this.max = max; 
     } 
     else { 
      throw new IllegalArgumentException("invalid range properties"); 
     } 
    }