Question

我是编码的新手，现在我只是把它作为一种爱好。我已经创建了一个模拟时钟，我有一个jlabel设置告诉我已经过了多少分钟。但是，我似乎无法弄清楚我用setText（“....”）做错了什么来更新Jlabel。简而言之，它只是没有更新标签，它停留在原始分钟。

Stackverflow对我来说至关重要，我有点尴尬，我甚至不得不问这个问题，但我似乎无法找到解决方案。

如果答案在某个地方而且我还没有找到，我道歉。我认为可能是相关的代码位在这里......

        //Minute Counter
        JLabel label = new JLabel();
        System.out.println(getMinuteCount(secondAngle));
        label.setText(String.valueOf(getMinuteCount(secondAngle))+" minutes have passed.");
        add(label);

...和...

        public void rotate()
{
    double time = .01;
    minuteAngle = minuteAngle-time;
    hourAngle = hourAngle-time/12;
    secondAngle = secondAngle-time*60;
}

public int getMinuteCount(double secondAngle)
{
    int secondAngleInt = (int) secondAngle;
    if (secondAngleInt==91)
    {
        minuteCount = minuteCount + 1;
    }    

    return minuteCount;
}

然而，这是我的整个代码供参考。（请原谅不专业的布局。我还在学习:)）

任何帮助都会非常感激。祝你有美好的一天！

public class Clock extends JPanel{

double hour = Double.parseDouble(JOptionPane.showInputDialog(null, "What hour is it?", "I need the time.", JOptionPane.PLAIN_MESSAGE));
double minutes = Double.parseDouble(JOptionPane.showInputDialog(null, "How many minutes have passed in this hour?", "I need the time.", JOptionPane.PLAIN_MESSAGE));
double Area = 400;
int minuteCount = 0;
int x0 = 300;
int y0 = 300;
double a = Math.sqrt(4*Area/Math.sqrt(3));
double h = a*Math.sqrt(3)/2;
double minuteAngle = 90-(360*minutes/60);
double hourAngle = 90-(360*hour/12);
double secondAngle = 90;

@Override
public void paint(Graphics g)
{
    super.paint(g);

    if (minuteAngle<0)
    {
        minuteAngle = 360 + minuteAngle;
    }

    if (hourAngle<0)
    {
        hourAngle = 360 + hourAngle;
    }

    if (secondAngle<0)
    {
        secondAngle = 360 + secondAngle;
    }

    //Draws the Second Hand Line
        Graphics2D secondLine = (Graphics2D) g;
        double[] secondEndpoints = getEndPoints(220+h, secondAngle);
        Shape secondl = new Line2D.Double(x0, y0, secondEndpoints[0], secondEndpoints[1]);
        secondLine.setColor(Color.red);
        secondLine.setStroke(new BasicStroke(2));
        secondLine.draw(secondl);

    //Draws the Minaute Hand Line
        Graphics2D minuteLine = (Graphics2D) g;
        double[] minuteEndpoints = getEndPoints(220, minuteAngle);
        Shape minutel = new Line2D.Double(x0, y0, minuteEndpoints[0], minuteEndpoints[1]);
        minuteLine.setColor(Color.black);
        minuteLine.setStroke(new BasicStroke(5));
        minuteLine.draw(minutel);

    //Draws the Minuate Hand Head
        Graphics2D minuteHead = (Graphics2D) g;
        Path2D.Double minutePath = new Path2D.Double();
        double[][] minuteHeadPoints = new double[3][2];
        minuteHeadPoints=getTriPoints(220, minuteAngle);
        minutePath.moveTo(minuteHeadPoints[0][0], minuteHeadPoints[0][1]);
        minutePath.lineTo(minuteHeadPoints[1][0], minuteHeadPoints[1][1]);
        minutePath.lineTo(minuteHeadPoints[2][0], minuteHeadPoints[2][1]);
        minutePath.lineTo(minuteHeadPoints[0][0], minuteHeadPoints[0][1]);
        minuteHead.setColor(Color.black);
        minuteHead.fill(minutePath);

    //Draws the Hour Hand Line
        Graphics2D line = (Graphics2D) g;
        double[] endpoints = getEndPoints(120, hourAngle);
        Shape l = new Line2D.Double(x0, y0, endpoints[0], endpoints[1]);
        line.setColor(Color.black);
        line.setStroke(new BasicStroke(5));
        line.draw(l);

    //Draws the Hour Hand Head
        Graphics2D tri = (Graphics2D) g;
        Path2D.Double path = new Path2D.Double();
        double[][] tripoints = new double[3][2];
        tripoints=getTriPoints(120, hourAngle);
        path.moveTo(tripoints[0][0], tripoints[0][1]);
        path.lineTo(tripoints[1][0], tripoints[1][1]);
        path.lineTo(tripoints[2][0], tripoints[2][1]);
        path.lineTo(tripoints[0][0], tripoints[0][1]);
        tri.setColor(Color.black);
        tri.fill(path);

    //Draws the Clock
        Graphics2D object = (Graphics2D) g;
        object.setColor(Color.black);
        object.fillOval(x0-10,y0-10,20,20);

        Graphics2D clockedge = (Graphics2D) g;
        clockedge.setColor(Color.black);
        clockedge.setStroke(new BasicStroke(2));
        clockedge.drawOval(x0-230,y0-230,460,460);

    //Minute Counter
        JLabel label = new JLabel();
        System.out.println(getMinuteCount(secondAngle));
        label.setText(String.valueOf(getMinuteCount(secondAngle))+" minutes have passed.");
        add(label);
}

public static void main(String[] args)throws InterruptedException
{
    JFrame frame = new JFrame("Some Shapes");
    Clock clock = new Clock();
    frame.add(clock);
    frame.setSize(600, 600);
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    int j=0;
    while (true)
    {
        clock.rotate();
        clock.repaint();
        Thread.sleep(1);
    }
}

public double[] getEndPoints(double radius, double angle)
{
    double[] endpoints = new double[2];
    double a = Math.sqrt(4*Area/Math.sqrt(3));
    double h = a*Math.sqrt(3)/2;

    if (angle%360==0)
    {
        endpoints[0]=x0+radius-h;
        endpoints[1]=y0;
    }

    if (0<angle%360 && angle%360<90)
    {
        endpoints[0]=x0+(radius-h)*Math.cos(Math.toRadians(angle));
        endpoints[1]=y0-(radius-h)*Math.sin(Math.toRadians(angle));
    }

    if (angle%360==90)
    {
        endpoints[0]=x0;
        endpoints[1]=y0-radius+h;
    }

    if (90<angle%360 && angle%360<180)
    {
        double phi = 180-angle;
        endpoints[0]=x0-(radius-h)*Math.cos(Math.toRadians(phi));
        endpoints[1]=y0-(radius-h)*Math.sin(Math.toRadians(phi));
    }

    if (angle%360==180)
    {
        endpoints[0]=x0-radius+h;
        endpoints[1]=y0;
    }

    if (180<angle%360 && angle%360<270)
    {
        double phi = angle-180;
        endpoints[0]=x0-(radius-h)*Math.cos(Math.toRadians(phi));
        endpoints[1]=y0+(radius-h)*Math.sin(Math.toRadians(phi));
    }

    if (angle%360==270)
    {
        endpoints[0]=x0;
        endpoints[1]=y0+radius-h;
    }

    if (270<angle%360 && angle%360<360)
    {
        double phi = 360-angle;
        endpoints[0]=x0+(radius-h)*Math.cos(Math.toRadians(phi));
        endpoints[1]=y0+(radius-h)*Math.sin(Math.toRadians(phi));
    }

    return endpoints;
}

public double[][] getTriPoints(double radius, double angle)
{
    double a = Math.sqrt(4*Area/Math.sqrt(3));
    double[][] tripoints = new double[3][2];
    double h = a*Math.sqrt(3)/2;

    if (angle%360==0)
    {
        tripoints[0][0]=x0+radius;
        tripoints[0][1]=y0;
        tripoints[1][0]=x0+radius-h;
        tripoints[1][1]=y0+a/2;
        tripoints[2][0]=x0+radius-h;
        tripoints[2][1]=y0-a/2;
    }

    if (0<angle%360 && angle%360<90)
    {
        tripoints[0][0]=x0+radius*Math.cos(Math.toRadians(angle));
        tripoints[0][1]=y0-radius*Math.sin(Math.toRadians(angle));
        tripoints[1][0]=x0+radius*Math.cos(Math.toRadians(angle))-a*Math.cos(Math.toRadians(30+angle));
        tripoints[1][1]=y0-radius*Math.sin(Math.toRadians(angle))+a*Math.sin(Math.toRadians(30+angle));
        tripoints[2][0]=x0+radius*Math.cos(Math.toRadians(angle))-a*Math.cos(Math.toRadians(angle-30));
        tripoints[2][1]=y0-radius*Math.sin(Math.toRadians(angle))+a*Math.sin(Math.toRadians(angle-30));
    }

    if (angle%360==90)
    {
        tripoints[0][0]=x0;
        tripoints[0][1]=y0-radius;
        tripoints[1][0]=x0+a/2;
        tripoints[1][1]=y0-radius+h;
        tripoints[2][0]=x0-a/2;
        tripoints[2][1]=y0-radius+h;
    }

    if (90<angle%360 && angle%360<180)
    {
        double phi = 180-angle;
        tripoints[0][0]=x0-radius*Math.cos(Math.toRadians(phi));
        tripoints[0][1]=y0-radius*Math.sin(Math.toRadians(phi));
        tripoints[1][0]=x0-radius*Math.cos(Math.toRadians(phi))+a*Math.cos(Math.toRadians(30+phi));
        tripoints[1][1]=y0-radius*Math.sin(Math.toRadians(phi))+a*Math.sin(Math.toRadians(30+phi));
        tripoints[2][0]=x0-radius*Math.cos(Math.toRadians(phi))+a*Math.cos(Math.toRadians(phi-30));
        tripoints[2][1]=y0-radius*Math.sin(Math.toRadians(phi))+a*Math.sin(Math.toRadians(phi-30));
    }

    if (angle%360==180)
    {
        tripoints[0][0]=x0-radius;
        tripoints[0][1]=y0;
        tripoints[1][0]=x0-radius+h;
        tripoints[1][1]=y0-a/2;
        tripoints[2][0]=x0-radius+h;
        tripoints[2][1]=y0+a/2;
    }

    if (180<angle%360 && angle%360<270)
    {
        double phi = angle-180;
        tripoints[0][0]=x0-radius*Math.cos(Math.toRadians(phi));
        tripoints[0][1]=y0+radius*Math.sin(Math.toRadians(phi));
        tripoints[1][0]=x0-radius*Math.cos(Math.toRadians(phi))+a*Math.cos(Math.toRadians(30+phi));
        tripoints[1][1]=y0+radius*Math.sin(Math.toRadians(phi))-a*Math.sin(Math.toRadians(30+phi));
        tripoints[2][0]=x0-radius*Math.cos(Math.toRadians(phi))+a*Math.cos(Math.toRadians(phi-30));
        tripoints[2][1]=y0+radius*Math.sin(Math.toRadians(phi))-a*Math.sin(Math.toRadians(phi-30));
    }

    if (angle%360==270)
    {
        tripoints[0][0]=x0;
        tripoints[0][1]=y0+radius;
        tripoints[1][0]=x0-a/2;
        tripoints[1][1]=y0+radius-h;
        tripoints[2][0]=x0+a/2;
        tripoints[2][1]=y0+radius-h;
    }

    if (270<angle%360 && angle%360<360)
    {
        double phi = 360-angle;
        tripoints[0][0]=x0+radius*Math.cos(Math.toRadians(phi));
        tripoints[0][1]=y0+radius*Math.sin(Math.toRadians(phi));
        tripoints[1][0]=x0+radius*Math.cos(Math.toRadians(phi))-a*Math.cos(Math.toRadians(30+phi));
        tripoints[1][1]=y0+radius*Math.sin(Math.toRadians(phi))-a*Math.sin(Math.toRadians(30+phi));
        tripoints[2][0]=x0+radius*Math.cos(Math.toRadians(phi))-a*Math.cos(Math.toRadians(phi-30));
        tripoints[2][1]=y0+radius*Math.sin(Math.toRadians(phi))-a*Math.sin(Math.toRadians(phi-30));
    }

    return tripoints;
}

public void rotate()
{
    double time = .01;
    minuteAngle = minuteAngle-time;
    hourAngle = hourAngle-time/12;
    secondAngle = secondAngle-time*60;
}

public int getMinuteCount(double secondAngle)
{
    int secondAngleInt = (int) secondAngle;
    if (secondAngleInt==91)
    {
        minuteCount = minuteCount + 1;
    }    

    return minuteCount;
}

}

Answer 1

public static void main(String[] args)throws InterruptedException
{
    JFrame frame = new JFrame("Some Shapes");
    Clock clock = new Clock();
    frame.add(clock);
    frame.setSize(600, 600);
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    int j=0;
    while (true)
    {
        clock.rotate();
        clock.repaint();
        Thread.sleep(1);
    }
}

您正在事件调度线程（EDT）之外绘制任何内容。

在Swing中，EDT是唯一可以在屏幕上实际绘制的线程。当您在框架上调用setVisible(true)时，它会自动启动。

因此，如果您想在屏幕上更改某些内容，则必须将EDT中的更改排入队列。您需要使用SwingUtilities：

 while (true)
    {
        clock.rotate();
        SwingUtilities.runLater(()->clock.repaint());
        Thread.sleep(1);
    }

JLabel和setText误解

1 个答案: