Quicksort java

//GOD's quicksort
public static <E extends Comparable<E>> List<E> sort(List<E> col) {
  if (col == null || col.isEmpty())
    return Collections.emptyList();
  else {
    E pivot = col.get(0);
    Map<Integer, List<E>> grouped = col.stream()
      .collect(Collectors.groupingBy(pivot::compareTo));
    return Stream.of(sort(grouped.get(1)), grouped.get(0), sort(grouped.get(-1)))
      .flatMap(Collection::stream).collect(Collectors.toList());
  }
}

Source: rosettacode.org

Quicksort for arraylist

public static ArrayList<Vehicle> quickSort(ArrayList<Vehicle> list)
{
    if (list.isEmpty()) 
        return list; // start with recursion base case
    ArrayList<Vehicle> sorted;  // this shall be the sorted list to return, no needd to initialise
    ArrayList<Vehicle> smaller = new ArrayList<Vehicle>(); // Vehicles smaller than pivot
    ArrayList<Vehicle> greater = new ArrayList<Vehicle>(); // Vehicles greater than pivot
    Vehicle pivot = list.get(0);  // first Vehicle in list, used as pivot
    int i;
    Vehicle j;     // Variable used for Vehicles in the loop
    for (i=1;i<list.size();i++)
    {
        j=list.get(i);
        if (j.compareTo(pivot)<0)   // make sure Vehicle has proper compareTo method 
            smaller.add(j);
        else
            greater.add(j);
    }
    smaller=quickSort(smaller);  // capitalise 's'
    greater=quickSort(greater);  // sort both halfs recursively
    smaller.add(pivot);          // add initial pivot to the end of the (now sorted) smaller Vehicles
    smaller.addAll(greater);     // add the (now sorted) greater Vehicles to the smaller ones (now smaller is essentially your sorted list)
    sorted = smaller;            // assign it to sorted; one could just as well do: return smaller

    return sorted;
}

Source: stackoverflow.com

Similar codes

15 votes356 views2 answers
Conversion of string to integer in java
Java
15 votes396 views5 answers
Java round double to 2 decimals
Java
0 vote362 views1 answer
Shortcut to find a class in java project eclipse
Java
2 votes320 views1 answer
Restart application programmatically android
Java
-1 vote314 views1 answer
Can a method be abstract and final in abstract class
Java
0 vote351 views1 answer
Get value from 2d array java
Java
-1 vote311 views1 answer
Input 3 int 1 line in java
Java
3 votes315 views3 answers
Ternary operator in java
Java
0 vote335 views1 answer
Como limitar o random em java
Java
0 vote331 views2 answers
Can abstract class have non abstract methods in java
Java