Question

我尝试运行此代码以使用JFrame

制作图像

主要课程

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

public class main {

    public static void main(String[] args){
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setTitle("kek");

        f.add (new GraphicsSurface());

        f.setSize(512, 512);
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }
}

GraphicsSurface类

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JComponent;

public class GraphicsSurface extends JComponent {

    public GraphicsSurface() {
    }

    public void paint (Graphics g) {
        int end = 0;
        long redint = 0, greenint = 0, blueint = 0;
        int xstart = 0, ystart = 0, xend = 0, yend = 0;
        double y = 0, x = 0;
        double width = 80;
        double angle = 0;
        double endpoint = 255;
        double curveintensitya = 1.4, curveintensityb = -0.9;
        double curvestarta = 30, curvestartb = 150;
        double curvelengtha = 15, curvelengthb = 30;
        double redvalue = 0, greenvalue = 0, bluevalue = 0;
        while (end == 0) {          

            Graphics2D g2d = (Graphics2D) g;            
            redvalue = 100 + (y / 2.56);
            greenvalue = 50 + (y / 1.28);
            bluevalue = 200 + (y / 5.12);
            redint = Math.round(redvalue);
            greenint = Math.round(greenvalue);
            blueint = Math.round(bluevalue);

            if (y >= curvestarta && y < (curvestarta + curvelengtha)) {
                angle = angle + (curveintensitya / curvelengtha);
            }
            if (y >= curvestartb && y < (curvestartb + curvelengthb)) {
                angle = angle + (curveintensityb / curvelengthb);
            }

            width = width + angle;
            if (width > 512) {
                width = 512;
            }
            x = Math.round(width);
            xend = (int) x;
            ystart = (int) y;
            yend = ystart;
            y = y + 1;

            if (y > endpoint) {
                end = 1;
            }

            g2d.setColor(new Color(redint, greenint, blueint, 255));

            g2d.drawLine(xstart, ystart, xend, yend);
        }
    }
}

但我在控制台中得到了这个：

at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

我想知道导致问题的原因以及解决问题的方法。

Answer 1

问题在于这一行

g2d.setColor(new Color(redint, greenint, blueint, 255));

代码中 redint，greenint 和 blueint 的类型属于long类型。但Color的构造函数包含int或long。

您可以参考文档here

解决问题的方法是：将这些类型从long更改为int并进行适当的投射。

java awt事件队列/调度线程未知源错误？

1 个答案: