Fonts and Graphics
Fonts, Random Numbers and Timers - Con't
Here you can see how random numbers are generated. You have to call Math.random() (the funcion random() from the Java package Math) which returns a floating point pseudo-random number between 0 and 1. To produce bigger numbers you must multiply the result with an integer. The expression (int) "casts" the floating point
return value of the random function to the integer value you need for your variable. Number positions behind the decimal point are cut off when you cast that way, not rounded!
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//Sourcecode
import java.awt.*;
import java.applet.*;
//demonstrates the use of random numbers
//this program produces a number between 1 and 6 when you click
public class Project7 extends Applet
{
int randomNumber;
public boolean mouseDown(Event evt,int x,int y)
{
//here it all happens.. Math.random() returns a floating point number
//between 0 and 1, so you have to multiply with an integer to produce
//integer random numbers and finally add 1 to exclude the 0
randomNumber=(int)(Math.random()*6)+1;
repaint();
return true;
}
public void paint(Graphics g)
{
g.setColor(Color.red);
g.setFont(new Font("Helvetica",Font.PLAIN,12));
g.drawString
("Click for random number between 1 and 6", 30,20);
g.setColor(Color.blue);
g.setFont(new Font("Helvetica",Font.BOLD,180));
//in the beginning randomNumber is 0, so we suppress it here
if(randomNumber!=0)
g.drawString(""+randomNumber, 100,210);
}
}
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