i am trying to use this function but it is giving that index is -1. so what can i do
int[] veer = {14,25,14,56,15,36,56,77,18,29,49};
int a = Arrays.asList(veer).indexOf(14);
System.out.println("my array at position 14 is :" + (a));
2 Answers
I assume, you want to learn/test what indexOf is doing. The problem is, that Arrays.asList(veer) returns list containing one element - whole array.
When I split the code to multiple lines, it is doing:
int[] orig = {14,25,14,56,15,36,56,77,18,29,49};
List<int[]> origList = Arrays.asList(orig);
and that's why, your indexOf is not able to find 14 in a list, because simply said, there is no integer in list.
When you use wrapper type, it works as you might expect
Integer[] veer = {14,25,14,56,15,36,56,77,18,29,49};
List<Integer> list = Arrays.asList(veer);
int a = list.indexOf(25); // I changed to 25
System.out.println("my array at position 25 is :" + a);
which prints index 1.
To learn about wrapping/unwrapping array, you can read more here Converting Array of Primitives to Array of Containers in Java but changing int[] to Integer[] is simplest in this case (you are not forced by API to accept int[]).
1 Comment
Betlista
I'd like downvoters to let me know what they do not agree with !
In your code
int[] veer = {14,25,14,56,15,36,56,77,18,29,49};
to
Integer[] veer = {14,25,14,56,15,36,56,77,18,29,49};
because indexOf expect a object type since it is primitive it is return as -1(-1 represents not found)
answered Feb 20, 2018 at 12:00
Sasikumar Murugesan
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array[indexNumber]to print the element at that index??indexOfreturns the location of the first occurrence of this value, not the element at that index. If you are using arrays why do you not use the[]operator? Or did you mean something else?