I received a recruiter call, and then had a call with the hiring manager a week later. The manager call went well; it was mostly about my past experience, with some questions on Kafka's exactly-once delivery. After that, there was a coding round, which I felt I did well on. However, because I did not use Java 8 features, they rejected me.

private static Map<String, Integer> namesToNumPurchases = new HashMap<String, Integer>() { { put("Chris", 10); put("Bob", 5); put("David", 5); put("Sue", 12); put("Jim", 3); } };

/* Required output:

3: Jim
5: Bob, David
10: Chris
12: Sue

*/

Find the occurrence position of a string in a sequence of characters.