package org.nhooo.example.lang; import java.util.HashMap; import java.util.Map; public class NumberOccurrenceInArray { public static void main(String[] args) { int[] numbers = new int[]{1, 8, 3, 4, 3, 2, 5, 7, 3, 1, 4, 5, 6, 4, 3}; Map<Integer, Integer> map = new HashMap<>(); for (int key : numbers) { if (map.containsKey(key)) { int occurrence = map.get(key); occurrence++; map.put(key, occurrence); } else { map.put(key, 1); } } for (Integer key : map.keySet()) { int occurrence = map.get(key); System.out.println(key + " occur " + occurrence + " time(s)."); } } }
结果是:
1 occur 2 time(s). 2 occur 1 time(s). 3 occur 4 time(s). 4 occur 3 time(s). 5 occur 2 time(s). 6 occur 1 time(s). 7 occur 1 time(s). 8 occur 1 time(s).