Driver.java

import java.io.*;
import java.util.*;

public class Driver {
    public static void main (String[] args) {
	ArrayList[] buckets = new ArrayList[10];
	
	for (int i = 0; i < 10; i++) {
	    buckets [i] = new ArrayList();
	}

	int [] a = new int [4];

	Random r = new Random();
	
	for (int i = 0; i < 4; i++) {
	    a[i]= r.nextInt(9999);
	}

	int n = 0;

	for (int i = 0;i < a.length; i++) {
	    buckets [(a[i] / 10^ n ) %10 ] .add ( a[i]);
	}

	//	public String toString() {
	//    String s = Arrays.toString(a);
	//   return ArrayLists.toArray ();
	//}

	System.out.println (" " + buckets[0]);
    }
}