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Easy Learn Java: Programming Articles, Examples and Tips - Page 37


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How can generate absolute unique number without using complicated math functions

Go to all tips in Security

Question: How can I generate absolute unique number without using complicated math functions? Not pseudo random from Java API...

I do not need it for high security; I need to have a unique Id for database connection...

Answer: Combine any of the following:

  • IP address
  • process id
  • random number (from Java API)
  • Date(month,day,year)
  • Time(hour,minute,second, millisecond) and then put them together like this:

IPIPIPMonthDayYearHourSecond...Id..RND...

You can also put them in different order each time when you do it

Code:

//Here just simplest example on random() usage..
//Real working code is up to you :-)
public class RandomNumbers {

    private static void doRawRandomNumber() {

        double rawRandomNumber;

        rawRandomNumber = Math.random();
        System.out.println("-------------------------------------------------");
        System.out.println("Raw random number : " + rawRandomNumber);
        System.out.println("-------------------------------------------------");
        System.out.println("\n");
       
    }


    /**
     * Sole entry point to the class and application.
     * @param args Array of String arguments.
     */
    public static void main(String[] args) {
        doRawRandomNumber();
    }

}


Some another Java code examples for Math.random() you can find here



13 comments | Printer Friendly Page  Send to a Friend | Score: 2.09
Posted by jalex on Monday, March 31, 2003 (00:00:00) (21688 reads)

A couple of canvases inside my applet using BorderLayout...

Go to all tips in Swing, AWT

Question: A couple of canvases inside my applet using BorderLayout...
How I can find out their sizes? getSize() seems to only work with
the Applet class and not the Canvas class.

Answer: Applet is a Container, and do like this:

Component[] components = applet.getComponents();
for (int i = 0; i < components.length; i++) {
Dimension size = components[i].getSize();
}

***************************************
Our older tips: March 22, 2001 - October 21, 2002 read here.
All published and not published on site tips you can find here



130 comments | Printer Friendly Page  Send to a Friend | Score: 0
Posted by jalex on Thursday, March 27, 2003 (00:00:00) (3450 reads)

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