統計重複元素出現次數（字符串和數組）

一、字符串： 

public class 重複元素計數 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		System.out.println("");
		String str = sc.nextLine();
		HashMap<Character, Integer> hashMap = new HashMap<>();
		char[] chs = str.toCharArray();
		for (char c : chs) {
			if (hashMap.containsKey(c)) {
				Integer num = hashMap.get(c);
				num++;
				hashMap.put(c, num);
			}else {
				hashMap.put(c, 1);
			}
		}
		System.out.println(hashMap);
	}
}

運行結果：

 

二、數組：

public class ArrayTest {
    public static void main(String[] args) {
        array();
    }
    public static void array(){
        int[] arr = {4,5,3,4,6,2,3,4,5,8,6,7,5,8,4,3,2,4,5,6,7,5,4,3,5,6,7,5,4,};
        Map<Integer, Integer> map = new HashMap<>();
        for (int i = 0; i < arr.length; i++) {
            int m = arr[i];
            if (map.containsKey(m)){
                int num = map.get(arr[i]);
                num++;
                map.put(arr[i],num);
            }else {
                map.put(arr[i],1);
            }
        }
        System.out.println(map);
    }
}

打印結果：