- Java code
import java.awt.BasicStroke;import java.awt.Color;import java.awt.Dimension;import java.awt.Graphics;import java.awt.Graphics2D;import javax.swing.JPanel;import org.omg.CORBA.PUBLIC_MEMBER;public class Circle extends JPanel{ private int value; public Circle(){ } public Circle(int value){ this.value = value; } public int getValue(){ return value; } public void setValue(int value){ this.value = value; //System.out.print(value); repaint(); } protected void paintComponent(Graphics g){ super.paintComponent(g); int clockRadius = (int)(Math.min(getWidth(), getHeight())*0.8*0.5); int xCenter = getWidth()/2; int yCenter = getHeight()/2; g.setColor(Color.RED); g.drawOval(xCenter-clockRadius, yCenter-clockRadius, 2*clockRadius, 2*clockRadius); //System.out.print(value); int line1 = (int)(clockRadius); int line1X = (int) (xCenter-clockRadius*Math.cos(value*(2*Math.PI/60))); int line1Y = yCenter+value; g.drawLine(xCenter, yCenter, line1X, line1Y); } public Dimension getPreferredSize() { return new Dimension(100,100); } }这是我写的一段画出线条的类代码，经过调试后发现当我在不断改变value值后，通过system.out.print在setValue()函数中显示value的值是在不断变化的，可是在protected void paintComponent(Graphics g)中打印的value值却一直是0没有变化，所以我的图像根本不会有变化一直是静止的，这是为什么呢
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