解析整数中的数字

Question

I need to make a function that will fill a Rectangle with a color. The method looks like this

public void fillRect(Rectangle rect, int color)
{
    int red = color;
    int green = color;
    int blue = color;
    g.setColor(new Color(red, green, blue));
    g.fillRect(rect.getX(), rect.getY(), rect.getW(), rect.getH());
}

I would like to use an integer as parameter, for example 200100150 which would result in the value 200 for red (only the three first digits).

Is it possible to do this width java?

Answer 1

You can do it with '%' and '/' operations like this:

int blue = color % 1000;
color /= 1000;

int green = color % 1000;
color /= 1000;

int red = color;

Also you could add a simple validation at the beginning

if(color <= 99_999_999) { // I'm pretty sure that you need at least JDK7 to use '_' notation
    //do sth
}

Answer 2

If you know the number length (ie, it looks like all your integers will be of length 9), you can use modulus and (integer) division:

int red = color / 1000000;
int green = color % 1000000 / 1000;
int blue = color % 1000;

If not, you can turn the integer into a String, get the first three characters as a substring, and convert it back to an integer.

Answer 3

Converting to a string and get Substrings and convert them to integers again? Great idea.Here is my code

public void setColor(int color)
{
    String newColor = Integer.toString(color);
    g.setColor(new Color(Integer.parseInt(newColor.substring(0, 3)),
                         Integer.parseInt(newColor.substring(3, 6)),
                         Integer.parseInt(newColor.substring(6, 9))));
}

It will be much slower than passing the integer to the Color()? Im new in java and i want to make things my way.