Java：Mac终端无法显示Java Graphics

Question

I am trying to draw checkerboard using Java. I am new to Java. So any advices would be helpful.

UPDATE: I added in the main method. I compiled it successfully in the Mac terminal . However, when I did java Checkerboard , there was an ICON appearing at the bottom and then it disappeared and no graphics appeared. What's wrong in here? The code is as follow:

import acm.graphics.*;
import acm.program.*;

/*
*   This class draws a checkerboard on the graphics window.
*   The size of the chcekerboard is specified by the constants NROWS
*   and NCOLUMNS, and the checkerboard fills the vertical space available.
*/

public class Checkerboard extends GraphicsProgram   {

     public static void main(String[] args){
         Checkerboard c = new Checkerboard();
         c.run();
     }

    // Number of rows
    private static final int NROWS = 8;

    //Number of columns
    private static final int NCOLUMNS = 8;

    //Runs the program
    public void run() {
        int sqSize = getHeight() / NROWS;
        for(int i = 0; i < NROWS; i++)  {
            for(int j = 0; j < NCOLUMNS ; j++)  {
                int x = j * sqSize;
                int y = i * sqSize;
                GRect sq = new GRect(x,y,sqSize,sqSize);
                sq.setFilled( ((i+j) % 2) != 0);
                add(sq);
            }
        }
    }
}

Answer 1

You seem to be lacking the main method: public static void main(String[] args) that is run when you start your program.

(removed the edit I did before, which was meant to go in my own post)

Answer 2

Your class needs to have a main method with the signature

public static void main(String[] args)

for you to be able to run it.

After your edit:

Maybe you need a loop in the main method calling the run method? Something like:

boolean exit = false;
while (!exit) {
    c.run();
    // if something set exit to true
}