insertion sort algorithm java code example

Example 1: java insertion sort

/**
* Insertion sort algorithm, O(n^2) time complexity.
*/
public static void insertionSort(int[] arr) {
  int n = arr.length;
  for(int i = 1; i < n; i++) {
    int key = arr[i];
    int j = i - 1;
    //shift until you find the position to place the element 'key'
    while(j >= 0 && arr[j] > key) {
      arr[j+1] = arr[j];
      j--;
    }
    //place element 'key' in the correct position in the sorted part of the array
    arr[j+1] = key;
  }
}

Example 2: Insertion sort java descending order

// Insertion sort java descending order
import java.util.Arrays;
public class InsertionSortDescendingOrder
{
   public static void main(String[] args) 
   {
      int[] arrInput = { 50, 80, 10, 30, 90, 60 };
      System.out.println("Before Sorting: ");
      displayArray(arrInput);
      insertionSort(arrInput);
      System.out.println("\nAfter Sorting: ");
      displayArray(arrInput);
   }
   private static void insertionSort(int[] arrNumber) 
   {
      for(int a = 1; a < arrNumber.length; a++)
      {
         int toSort = arrNumber[a];
         int b = a;
         while(b > 0 && arrNumber[b - 1] < toSort) 
         {
            arrNumber[b] = arrNumber[b - 1];
            b--;
         }
         arrNumber[b] = toSort;
      }
   }
   public static void displayArray(int[] arrPrint) 
   {
      System.out.println(Arrays.toString(arrPrint));
   }
}

Example 3: insertion sort java

Insertion program
public class InsertionSortExample
{
   public void sort(int[] arrNum)
   {
      int number = arrNum.length;
      for(int a = 1; a < number; ++a)
      {
         int keyValue = arrNum[a];
         int b = a - 1;
         while(b >= 0 && arrNum[b] > keyValue)
         {
            arrNum[b + 1] = arrNum[b];
            b = b - 1;
         }
         arrNum[b + 1] = keyValue;
      }
   }
   static void displayArray(int[] arrNum)
   {
      int num = arrNum.length;
      for(int a = 0; a < num; ++a)
      {
         System.out.print(arrNum[a] + " ");
      }
      System.out.println();
   }
   public static void main(String[] args)
   {
      int[] arrInput = { 50, 80, 10, 30, 90, 60 };
      InsertionSortExample obj = new InsertionSortExample();
      obj.sort(arrInput);
      displayArray(arrInput);
   }
}