Introduction

In this demo I have used NetBeans IDE 8.2 for debugging purpose. But you can use any java programming language compiler as per your availability..

public class Javaexcercise {
       public static int  findIndex (int[] myarray, int t) {
        if (myarray == null) return -1;
        int len = myarray.length;
        int i = 0;
        while (i < len) {
            if (myarray[i] == t) return i;
            else i=i+1;
        }
        return -1;
    }
    public static void main(String[] args) {
      int[] my_array = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
      System.out.println("Index position of 2 is: " + findIndex(my_array, 2));
      System.out.println("Index position of 7 is: " + findIndex(my_array, 7));
      System.out.println("Index position of 6 is: " + findIndex(my_array, 9));
       }
}

Result