java - Display Selection sorting and Quick Sorting -

i want check if algorithms correct quick sort method , selection sort method. believe have quick sorting correct , selection sorting correct may need correcting. how can display sorting back?

selection sorting

public class selectionsort {  // complexity of o(n2) public void selectionsort(int numbers[], int array_size) {      int i;     int j;     int min;      (i = 0; < array_size - 1; i++) {          min = i;          (j = + 1; j < array_size; j++) {              if (numbers[j] < numbers[min])                 min = j;          }          swap(numbers[i], numbers[min]);     } }  public void swap(int num1, int num2) {     int temp;     temp = num1;     num1 = num2;     num2 = temp; }  } 

quick sorting

public class quicksort {  // complexity of o(n log n). public void quicksort(int numbers[], int array_size) {      quicksort(numbers, 0, array_size - 1);  }  public void quicksort(int numbers[], int left, int right) {      int pivot;     int lefthold;     int righthold;      lefthold = left;     righthold = right;     pivot = numbers[left];      while (left < right) {          while ((numbers[right] >= pivot) && (left < right))             right--;          if (left != right) {             numbers[left] = numbers[right];             left++;         }          while ((numbers[left] <= pivot) && (left < right))             left++;          if (left != right) {             numbers[right] = numbers[left];             right--;          }     }      numbers[left] = pivot;     pivot = left;     left = lefthold;     right = righthold;      if (left < pivot)          quicksort(numbers, left, pivot - 1);      if (right > pivot)          quicksort(numbers, pivot + 1, right);  } } 

main class

public class sorttesting {  public static void main(string[] args) {      quicksort qsort = new quicksort();     selectionsort ssort = new selectionsort();      int i;     int numbers[] = { 12, 9, 4, 99, 120, 1, 3, 10 };      system.out.print("values in sort:\n");      (i = 0; < numbers.length; i++) {         system.out.print(numbers[i] + "  ");         system.out.println();     }      qsort.quicksort(numbers, 1);     ssort.selectionsort(numbers, 1);      //display sort of quicksort     //display sort of selectionsort  }  } 

your quicksort fine,but there problem swap function in selection sort.the problem is:

in java primitives passed value.

so, if pass 2 integers swap function swap not reflected in calling function. can corrected rather passing array , indices want swap . correct swap function is:

public void swap(int []numbers,int i,int min) {     int temp;     temp = numbers[i];     numbers[i] = numbers[min];     numbers[min]=temp; } 

and correct call is:

swap(numbers,i,min); 

now coming main function there type error you, have mentioned array lengths 1, wrong, alwasy advisable when mentioning array lengths in java use this

array_identifier.length

also provide same unsorted array other sorting algorithm, use method clone() clone unsorted array array , send selection sort , therefore correct main class is:

public class sorttesting {  public static void main(string[] args) {      quicksort qsort = new quicksort();     selectionsort ssort = new selectionsort();      int i;     int numbers[] = { 12, 9, 4, 99, 120, 1, 3, 10 };      system.out.print("values in sort:\n");      (i = 0; < numbers.length; i++) {         system.out.print(numbers[i] + "  ");         system.out.println();     }          int []numbers2=numbers.clone();     qsort.quicksort(numbers, numbers.length);/*mention correct array length*/             system.out.println("\nthe array after sorting using quick sort is");     for(int e:numbers)      system.out.print(e+"  ");         ssort.selectionsort(numbers2, numbers2.length);/*mention correct array length*/         system.out.println("\nthe array after sorting using selection sort is");     for(int e:numbers2)      system.out.print(e+"  ");           }  }