我無法弄清楚如何與改變的變量的paintComponent重繪

Question

int club_num = 0; 
private int angle = 90;  
private int startX = 72; 
private int startY = 329; 
private double endX = startX + clublength * Math.sin(Math.toRadians(angle)); 
private double endY = startY + clublength * Math.cos(Math.toRadians(angle)); 

@Override 
public void paintComponent(Graphics g){ 
    super.paintComponent(g); 
    g.setColor(Color.BLACK); 
    g.drawLine(startX, startY, (int)endX, (int)endY); //this is what i want to change 
} 
public class Keys extends KeyAdapter { 
    @Override 
    public void keyPressed(KeyEvent e){ 
     if (e.getKeyCode() == KeyEvent.VK_LEFT){ 
      club_num--; //ultimately changes endX and endY 
      if (club_num < 0) 
       club_num = club[0].length-1; //ultimately changes endX and endY 
      repaint(); 
     } 
     else if (e.getKeyCode() == KeyEvent.VK_RIGHT){ 
      club_num++; //ultimately changes endX and endY 
      if (club_num > club[0].length-1) 
       club_num = 0; //ultimately changes endX and endY 
      repaint(); 
     } 
    } 
} 

當按下後，一個按鈕和一個變量值改變稱爲repaint()方法，我想行[g.drawLine(startX, startY, (int)endX, (int)endY)]根據更新的變量參數來改變[endX and endY]。

Answer 1

找到答案！

我將此添加到我的腳本中，並將變量更改爲private double endX/endY，並添加了一個計時器對象。

public class TimerListener implements ActionListener { 
     public void actionPerformed(ActionEvent e) { 
      calcEndX(clublength, angle); 
      calcEndY(clublength, angle); 
     } 
    } 

    public void calcEndX(int clublength, int angle){ 
     endX = startX + clublength * Math.sin(Math.toRadians(angle)); 
    } 
    public void calcEndY(int clublength, int angle){ 
     endY = startY + clublength * Math.cos(Math.toRadians(angle)); 
    } 
    public double getEndX(){ 
     return endX; 
    } 
    public double getEndY(){ 
     return endY; 
    }