Pegar resolução da tela

public class MainClass {
  public static void main(String[] args) {
    Toolkit tk = Toolkit.getDefaultToolkit();
    Dimension d = tk.getScreenSize();
    System.out.println("Screen width = " + d.width);
    System.out.println("Screen height = " + d.height);

  }
}

package resolucaotela;

import java.awt.Dimension;
import java.awt.Toolkit;

public class ResolucaoTela {

    public static void main(String[] args) {
        Dimension tela = Toolkit.getDefaultToolkit().getScreenSize();
        int lar = (int) tela.getWidth();
        int alt = (int) tela.getHeight();
        System.out.println("Sua tela tem resolução " + lar + " x " + alt);
    }  
}

package resolucao;

import java.awt.Dimension;
import java.awt.Toolkit;

public class Resolucao {

    public static void main(String[] args) {
        Toolkit tk;
        tk = Toolkit.getDefaultToolkit();
        Dimension d = tk.getScreenSize();
        System.out.print("Sua resolção é de "+d.width);
        System.out.println(" X "+d.height);
    }
}