BucketSort.java

// Bucket sort in Java

import java.util.ArrayList;
import java.util.Collections;

public class BucketSort {
  public void bucketSort(float[] arr, int n) {
    if (n <= 0)
      return;
    @SuppressWarnings("unchecked")
    ArrayList<Float>[] bucket = new ArrayList[n];

    // Create empty buckets
    for (int i = 0; i < n; i++)
      bucket[i] = new ArrayList<Float>();

    // Add elements into the buckets
    for (int i = 0; i < n; i++) {
      int bucketIndex = (int) arr[i] * n;
      bucket[bucketIndex].add(arr[i]);
    }

    // Sort the elements of each bucket
    for (int i = 0; i < n; i++) {
      Collections.sort((bucket[i]));
    }

    // Get the sorted array
    int index = 0;
    for (int i = 0; i < n; i++) {
      for (int j = 0, size = bucket[i].size(); j < size; j++) {
        arr[index++] = bucket[i].get(j);
      }
    }
  }

  // Driver code
  public static void main(String[] args) {
    BucketSort b = new BucketSort();
    float[] arr = { (float) 0.42, (float) 0.32, (float) 0.33, (float) 0.52, (float) 0.37, (float) 0.47,
        (float) 0.51 };
    b.bucketSort(arr, 7);

    for (float i : arr)
      System.out.print(i + "  ");
  }
}