For aprimorado - duvidas

package javaapplication1;

/**
 *
 * @author joaosavio
 */
public class Main {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        int[] x = {5,6,9,8};
        int[][] y = {{1,2,3},{4,5},{6,7,8}};
         
        for (int i : x) {
            System.out.println(x[i]);            
        }
        
        for(int i[]: y) {
            for(int j: i) {
                System.out.println(); //????????????
                
            }
        }            
        
    }
}