如何使java.awt Graphics2D字符串出现在applet中的随机位置

Question

I started Java a few days ago, and was experimenting and fooling around with some Java codes in a Java tutorial I borrowed from the library.

It told me how to draw a string onto an applet using Graphics2D from java.awt and change its font color, size, type, etc.

Now I challenged myself to make the string appear in random places in the applet. I tried using Math.random() to change the xy coordinates of the string but the variable type was different and I found myself puzzled. Is there any way to make the string appear in random places every time I open the applet? (I'm going into moving the string with an .awt button later.)

Here is my code:

package game;
import java.awt.*;

public class Javagame extends javax.swing.JApplet{
    public void paint(Graphics screen) {
        Graphics2D screen2D = (Graphics2D) screen;
        Font font = new Font("Arial Black", Font.PLAIN, 20);
        screen2D.setFont(font);
        screen2D.drawString("Hello World!", 50, 50); /*right now it is set at 50, 50
        but I want random variables. Thanks*/

    }
}

Answer 1

You want to use something like:

screen2D.drawString("Hello World!", 
    (int)(Math.random()*width), 
    (int)(Math.random()*height));

Where width and height are the maximum values of X and Y you want. See this related question: " Generating random numbers in a range. "

Answer 2

You could try using the random class:

Random r = new Random();
int x = r.nextInt(100);
int y = r.nextInt(100);

This will generate a random integer between 0 and the value specified.

Answer 3

From memory, Math.ramdom() returns a double value 0-1 . The position parameters will require a int .

You need to cast the double value to an int .

screen2D.drawString("Hello World!", (int)(Math.round(Math.random() * getWidth()), (int)(Math.round(Math.random() * getWidth()));

Normally, if you do (int)doubleValue , it will simply trim of the trailing decimal values. This might be a good, this might be a bad thing. I tend to round the value first, but that's just me.