Where is Java’s Array indexOf?

There are a couple of ways to accomplish this using the Arrays utility class.

If the array is not sorted and is not an array of primitives:


If the array is primitives and not sorted, one should use a solution offered by one of the other answers such as Kerem Baydoğan’s, Andrew McKinlay’s or Mishax’s. The above code will compile even if theArray is primitive (possibly emitting a warning) but you’ll get totally incorrect results nonetheless.

If the array is sorted, you can make use of a binary search for performance:

java.util.Arrays.binarySearch(theArray, o)

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