What are the ways to iterate through a hashmap?

There are several ways to iterate through a HashMap.

1. set of entries

HashMap<String, Integer> map = new HashMap<>();
// 添加键值对
Iterator<Map.Entry<String, Integer>> iterator = map.entrySet().iterator();
while (iterator.hasNext()) {
    Map.Entry<String, Integer> entry = iterator.next();
    String key = entry.getKey();
    Integer value = entry.getValue();
    // 处理键值对
}

1. Return a set of all keys in the map.

HashMap<String, Integer> map = new HashMap<>();
// 添加键值对
for (String key : map.keySet()) {
    Integer value = map.get(key);
    // 处理键值对
}

1. Return a list of all the values in the given dictionary.

HashMap<String, Integer> map = new HashMap<>();
// 添加键值对
for (Integer value : map.values()) {
    // 处理值
}

1. You can use the forEach method in Java 8 to iterate through the key-value pairs in a HashMap.

HashMap<String, Integer> map = new HashMap<>();
// 添加键值对
map.forEach((key, value) -> {
    // 处理键值对
});