英文:
Math.random() function is not working in a for-loop
问题
在这段代码中，Math.random() 方法应该输出 1、2、3 或 4 中的一个数字，根据输出的数字，在相对位置绘制一个圆圈（RandomWalk Java 程序的一部分）。
但实际上，程序没有展示随机的圆点位置，它只打印向上移动的圆点（即只有当方向为 1 时表示向北移动），我对 Math.random() 方法是否存在问题感到困惑。
以下是代码：
int start_x = 200;
int start_y = 200;
double direction;
for (int i = 0; i < 20; i++)
{
// 生成一个介于 1 和 4 之间的随机整数
direction = (int) (Math.random() * 4) + 1;
// 北方
if (direction == 1)
{
g2.setColor(Color.BLUE);
Ellipse2D.Double circle1
= new Ellipse2D.Double(start_x - 2, start_y - 12, 4, 4);
g2.draw(circle1);
start_y -= 10;
}
// 南方
if (direction == 2)
{
g2.setColor(Color.BLUE);
Ellipse2D.Double circle1
= new Ellipse2D.Double(start_x - 2, start_y + 8, 4, 4);
g2.draw(circle1);
start_y += 10;
}
// 东方
if (direction == 3)
{
g2.setColor(Color.BLUE);
Ellipse2D.Double circle1
= new Ellipse2D.Double(start_x + 8, start_y - 2, 4, 4);
g2.draw(circle1);
start_x += 10;
}
// 西方
if (direction == 4)
{
g2.setColor(Color.BLUE);
Ellipse2D.Double circle1
= new Ellipse2D.Double(start_x - 12, start_y - 2, 4, 4);
g2.draw(circle1);
start_x -= 10;
}
}
英文:
In this piece of code, the Math.random() method is supposed to output either 1, 2, 3, or 4 and according to which number was outputted, draw a circle in a relative location (part of RandomWalk java program).
Instead of showing random dot locations, the program only prints dots going up (so only if(direction == 1) for North) was used, and I am confused if there is a problem with the Math.random() method that is making it do this.
Here is the code:
int start_x = 200;
int start_y = 200;
double direction;
for (int i = 0; i < 20; i++)
{
// Generates random integer between 1 and 4
direction = (int) Math.random() * 4 + 1;
// North
if (direction == 1)
{
g2.setColor(Color.BLUE);
Ellipse2D.Double circle1
= new Ellipse2D.Double(start_x - 2, start_y - 12, 4, 4);
g2.draw(circle1);
start_y -= 10;
}
// South
if (direction == 2)
{
g2.setColor(Color.BLUE);
Ellipse2D.Double circle1
= new Ellipse2D.Double(start_x - 2, start_y + 8, 4, 4);
g2.draw(circle1);
start_y += 10;
}
// East
if (direction == 3)
{
g2.setColor(Color.BLUE);
Ellipse2D.Double circle1
= new Ellipse2D.Double(start_x + 8, start_y - 2, 4, 4);
g2.draw(circle1);
start_x += 10;
}
if (direction == 4)
{
g2.setColor(Color.BLUE);
Ellipse2D.Double circle1
= new Ellipse2D.Double(start_x - 12, start_y - 2, 4, 4);
g2.draw(circle1);
start_x -= 10;
}
}
答案1
得分: 4
这可能是因为您将值转换得太早了。
请尝试以下内容：
direction = (int) (Math.random() * 4) + 1;
英文:
That's probably because you cast your value to early.
Try the following:
direction = (int) (Math.random() * 4) + 1;
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