如何添加新的键值对以及如何循环获取每个值？

my_dict = {}
my_dict['new_key'] = 'new_value'

let myObj = {};
myObj['newKey'] = 'newValue';

import java.util.HashMap;

HashMap<String, String> myMap = new HashMap<>();
myMap.put("newKey", "newValue");

for key, value in my_dict.items():
    print(value)

for (let key in myObj) {
    if (myObj.hasOwnProperty(key)) {
        console.log(myObj[key]);
    }
}

for (String key : myMap.keySet()) {
    System.out.println(myMap.get(key));
}

if 'new_key' not in my_dict:
    my_dict['new_key'] = 'new_value'

String value = myMap.getOrDefault("newKey", "defaultValue");