Question

程序可以运行，但它没有输出我想要输出的内容。看，我想要7个同心圆弧，彩色为彩虹。我得到的是7个同心圆弧，红色和黄色。我按此顺序需要颜色：

红色，黄色，粉色，绿色，紫色，橙色，蓝色

我需要添加或更改什么？我正在使用if else语句在颜色之间交替。这就是它在红色和黄色之间交替的原因。我在其他if语句中添加了另一组if else，我想我可以用它们来进一步替换。

我对java和循环很新。我以为我可以使用，如果是，或者为颜色做循环。

import javax.swing.JPanel;
import java.awt.*;
public class rainbowpanel extends JPanel
{

private final int MAX_WIDTH = 300, NUM_RINGS = 7, RING_WIDTH = 20;



public rainbowpanel ()
{
setBackground (Color.white);
setPreferredSize (new Dimension(300,300));
}




    public void paintComponent (Graphics page)

    {
        super.paintComponent (page);
        int x = 0, y = 0, diameter = MAX_WIDTH;
        page.setColor (Color.yellow);
     for (int count = 0; count < NUM_RINGS; count++)


        {
            if (page.getColor() == Color.yellow) // alternate colors
            page.setColor (Color.red);
            else
            page.setColor (Color.yellow);
            page.fillArc (x, y, diameter, diameter, 0, 180);




            diameter -= (2 * RING_WIDTH);
            x += RING_WIDTH;
            y += RING_WIDTH;
            }



            {
            if (page.getColor() == Color.yellow) // alternate colors
                page.setColor (Color.pink);
            else
                page.setColor (Color.orange);
                   page.fillArc (x, y, diameter, diameter, 0, 180);



            //diameter -= (2 * RING_WIDTH);
            //x += RING_WIDTH;
            //y += RING_WIDTH;
}




            page.setColor (Color.white);
            page.fillArc (x, y, diameter, diameter, 0, 180);
}
}

您必须从此文件中运行它：

import javax.swing.JFrame;
public class rainbow

{

public static void main (String[] args)
{
JFrame frame = new JFrame ("Rainbow");
frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);


rainbowpanel panel = new rainbowpanel();
frame.getContentPane().add(panel);
frame.pack();
frame.setVisible(true);
}
}

Answer 1

尝试这样的事情：

public void paintComponent (Graphics page)
{
    super.paintComponent (page);
    int x = 0, y = 0, diameter = MAX_WIDTH;

    Color myColors[] = { Color.red, Color.yellow, Color.pink, Color.green, Color.purple, Color.orange, Color.blue };

    for (int count = 0; count < NUM_RINGS; count++)
    {
        page.setColor (myColors[count%NUM_RINGS]);
        page.fillArc (x, y, diameter, diameter, 0, 180);

        diameter -= (2 * RING_WIDTH);
        x += RING_WIDTH;
        y += RING_WIDTH;
    }
}

只需一个循环就可以满足所有绘图。 count%NUM_RINGS将阻止数组超出界限错误，如果您设置的环数多于颜色，则它们将从头开始循环。

Answer 2

请尝试此代码。这段代码有点棘手。我知道这不是专业的编码方式。

public class rainbowpanel extends JPanel{
private final int MAX_WIDTH = 300, NUM_RINGS = 7, RING_WIDTH = 20;

public rainbowpanel ()
{
    setBackground (Color.white);
    setPreferredSize (new Dimension(300,300));
    }
public void paintComponent (Graphics page)
{
super.paintComponent (page);
int x = 0, y = 0, diameter = MAX_WIDTH;
page.setColor (Color.red);
for (int count = 0; count < 2; count++)
{
if (page.getColor() == Color.yellow) // alternate colors
page.setColor (Color.red);
else
page.setColor (Color.yellow);
page.fillArc (x, y, diameter, diameter, 0, 180);

diameter -= (2 * RING_WIDTH);
x += RING_WIDTH;
y += RING_WIDTH;
}
for (int count = 0; count < 2; count++)
{
if (page.getColor() == Color.blue) // alternate colors
page.setColor (Color.green);
else
page.setColor (Color.blue);
page.fillArc (x, y, diameter, diameter, 0, 180);

diameter -= (2 * RING_WIDTH);
x += RING_WIDTH;
y += RING_WIDTH;
}
for (int count = 0; count < 2; count++)
{
if (page.getColor() == Color.pink) // alternate colors
page.setColor (Color.LIGHT_GRAY);
else
page.setColor (Color.pink);
page.fillArc (x, y, diameter, diameter, 0, 180);

diameter -= (2 * RING_WIDTH);
x += RING_WIDTH;
y += RING_WIDTH;
}
for (int count = 0; count < 1; count++)
{
if (page.getColor() == Color.cyan) // alternate colors
page.setColor (Color.LIGHT_GRAY);
else
page.setColor (Color.cyan);
page.fillArc (x, y, diameter, diameter, 0, 180);

diameter -= (2 * RING_WIDTH);
x += RING_WIDTH;
y += RING_WIDTH;
}

}
}

java绘制彩虹

2 个答案: