Find the most frequent number in an array
Please add a /** */ javadoc sentence, clarifying what happens in e.g. the case where { 5, 5, 6, 6 } is passed in.

The name findMostFrequentNumber() seems a bit verbose, when mode() or findMode() would suffice.

Consider numbers instead of givenArray. In any event, "array" is redundant with int[].

Consider eliding the null check. Caller gets what he deserves if the contract is "caller shall provide an array of numbers". NPE is appropriate if caller fails to do that. Or throw your own exception. Returning zero is clearly inappropriate, as caller cannot distinguish between an input of null and an input of { 5, 6, 0, 0, 0, 5 }.

In numberOccuranceMap, the "map" is redundant with the Map declaration. (Also, typo: occurrence.) Consider a "to" name for your maps, such as numToOccurences or numToCount.

    int mostFrequentOccurance = 0;


This sounds like it is simply modeCount, and the mostFrequentNumber we will return is simply mode.

            numberOccuranceMap.put(number, numberOccuranceMap.get(number) + 1);


Your get() call could specify a 2nd argument default value of zero, which would obviate the need for the containsKey() test.

        if (numberOccuranceMap.get(number) &gt; mostFrequentOccurance) {
            mostFrequentNumber = number;
            mostFrequentOccurance = numberOccuranceMap.get(number);
        }


Here we find the answer to the javadoc question above: last one wins!