BucketsSort.java

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

public class BucketsSort {
    private ArrayList<Integer>[] buckets = new ArrayList[100];
    private int[] nums = new int[10];

    public String toString() {
        return "Nums: " +  Arrays.toString(nums);
    }

    public String printBuckets() {
        return "Buckets: " + Arrays.toString(buckets);
    }
    
    public BucketsSort() {
        for (int i = 0; i < 10; i++) {
              buckets[i] = new ArrayList<Integer>();
        }
        Random r = new Random();
        for (int i = 0; i < nums.length; i++) {
            nums[i] = r.nextInt(8999)+1000;
        }
    }

    public void sortIntoBuckets(int n) {
        int value; 
        for (int i = 0;i<nums.length;i++) {
            value = (int)((nums[i]/(Math.pow(10,n))) % 10);
            buckets[value].add(nums[i]);
        }        
    }
    
    public void copyIntoArray() {
        int[] temp = new int[nums.length];
        int i=0;
        while (i < temp.length) {
            for (int j = 0; j < buckets.length; j++) {
                if( buckets[j].size() != 0) {
                    for (int k=0; k < buckets[j].size();k++) {
                        temp[i] = buckets[j].get(k);
                        i++;
                    }
                }
            }
        }
        nums = temp;
    }

    public void sort() {
        for (int n = 0; n < 4; n++) {
            //System.out.println("Digit: " + n);
            sortIntoBuckets(n);
            copyIntoArray();
            //System.out.println(printBuckets());
            //System.out.println(this);
            ArrayList<Integer>[] temp = new ArrayList[100];
            for (int i = 0; i < 10; i++) {
                temp[i] = new ArrayList<Integer>();
            }
            buckets = temp;
            
        }
    }
        
}