如何在同一个key HashMap Java中求和？

HashMap<String, Integer> map = new HashMap<>();
map.put("key1", 10);
map.put("key2", 20);
map.put("key3", 30);

HashMap<String, Integer> sumMap = new HashMap<>();
for (Map.Entry<String, Integer> entry : map.entrySet()) {
    String key = entry.getKey();
    Integer value = entry.getValue();
    
    if (sumMap.containsKey(key)) {
        int sum = sumMap.get(key) + value;
        sumMap.put(key, sum);
    } else {
        sumMap.put(key, value);
    }
}

for (Map.Entry<String, Integer> entry : sumMap.entrySet()) {
    String key = entry.getKey();
    Integer sum = entry.getValue();
    System.out.println("Key: " + key + ", Sum: " + sum);
}