在Java中计算二维数组中的整数出现次数

HashMap<Integer, Integer> countMap = new HashMap<>();

int[][] array = {{1, 2, 3}, {4, 5, 6}, {1, 2, 3}};
for (int i = 0; i < array.length; i++) {
    for (int j = 0; j < array[i].length; j++) {
        int num = array[i][j];
        if (countMap.containsKey(num)) {
            countMap.put(num, countMap.get(num) + 1);
        } else {
            countMap.put(num, 1);
        }
    }
}

for (Map.Entry<Integer, Integer> entry : countMap.entrySet()) {
    int num = entry.getKey();
    int count = entry.getValue();
    System.out.println("整数 " + num + " 出现次数为 " + count);
}