Question: (java) Hello! I am trying to write a program that among other things sorts an ArrayList using quick sort, I have tried many different things
(java)
Hello!
I am trying to write a program that among other things sorts an ArrayList using quick sort, I have tried many different things but right now I am getting a null pointer exception. Any suggestions would be appreciated.
Thank you, here is the code
import java.util.*;
public class BuiltIn {
private static final int[] ArrayS = null;
public static void main(String[] args) { Random r = new Random(); ArrayList
for (int i = 0; i < 10; i++) { int ran = r.nextInt(1000); Array.add(ran); System.out.println(Array.get(i)); }
int right; int left; for (int i = 0; i < 10; i++) { ArrayS = new int[Array.size()]; ArrayS[i] = (int) Array.get(i); System.out.println(ArrayS[i]);
}
ArrayS = sort(ArrayS, Array, left, right); System.out.println("Sorted Array:"); for (int i = 0; i < 10; i++) { System.out.println(ArrayS[i]); }
Stack Stack = new Stack<>(); Queue Queue = new LinkedList<>();
System.out.println("Queue:"); for (int i = 0; i < 10; i++) { Queue.add(Array.get(i)); System.out.println(Queue.remove());
}
System.out.println("Stack:");
for (int i = 0; i < 10; i++) { Stack.add(Array.get(i));
}
for (int i = 0; i < 10; i++) { System.out.println(Stack.pop()); }
}
private static int sort(int ArrayS[], ArrayList Array, int left, int right) { int index = partition(ArrayS, Array, left, right); if (left < index - 1) { sort(ArrayS, Array, left, index+1); } if (index < right) { sort(ArrayS, Array, index-1, right); } return index;
}
private static int partition(int ArrayS[], ArrayList Array, int left, int right) { right=ArrayS[0]; left=ArrayS[9]; int i = left; int j = right; int pivot = ArrayS[(left + right) / 2]; while (i <= j) { while (ArrayS[i] < pivot) { i++; } while (ArrayS[j] > pivot) { j--; } if (i <= j) { int temp = ArrayS[i]; ArrayS[i] = ArrayS[j]; ArrayS[j] = temp; i++; j--; } } for (int l = 0;l<10;l++){ System.out.println(ArrayS[l]); } return i; }
}
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