Greenfoot

2015/1/21

Getting a random number between 10.0 and 15.0 but with decimals?

2015/1/21

I want to have all my fireworks (yes, I am creating a scenario that just shoots fireworks) have a velocity between 10.0 and 15.0 yet include all decimals to a tenth. How can I do so

import greenfoot.*;  // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)
import java.awt.Color;
public class Rocket extends SmoothMover
{
    Color randomColor = new Color(Greenfoot.getRandomNumber(255), Greenfoot.getRandomNumber(255), Greenfoot.getRandomNumber(255), 255);
    private int Direction = Greenfoot.getRandomNumber(40)+210;
    public Rocket()
    {
       setRotation(Direction);
       GreenfootImage image;
       image = new GreenfootImage(10,10);
       image.setColor(randomColor);
       image.drawOval(0,0,10,10);
       image.fillOval(0,0,10,10);
       setImage(image);
    }
    public void act() 
    {
        // Add your action code here.
    }    
}

danpost

2015/1/22

Well, this:

int rand = 100+Greenfoot.getRandomNumber(51);

would set rand to an int value between 100 and 150. So,

double speed = (double)rand/10.0;

should do it. You could also do this:

double speed = 10.0+Math.random()*5.0;

to include an infinite number of speeds between 10 and 15.

DiplomatikCow

2015/1/22

And how would I proceed to input that value into a method in which the firework moves in its given direction at that random speed>

danpost

2015/1/22

Presuming the parameter of the method is of type double, you can just insert the expression on the right of my last assignment statement.

DiplomatikCow

2015/1/22

What......I don't understand doubles at all..... :(

danpost

2015/1/22

The SmoothMover class probably has a 'public void move(double distance)' method, or something like that. If so, you can just do:

// add instance field
private double speed = 10.0+Math.random()*5.0;
// and in act method
move(speed);

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Getting a random number between 10.0 and 15.0 but with decimals?