将 2 个不同对象的列表合并为一个组合对象答案

【问题标题】：Merge a list of 2 different objects into one combined object将 2 个不同对象的列表合并为一个组合对象
【发布时间】：2021-10-29 06:28:17
【问题描述】：

我需要将两个列表List<Phone>和List<PhoneTwo>合并为一个组合对象Combined，在Combined中只有一个字段，即phone

[
    {
        "phones": [
            {
                "id": 1,
                "phone": "44444444"
            },
            {
                "id": 2,
                "phone": "5555555"
            }
        ],
        "phonesTwo": [
            {
                "id": 1,
                "phone": "77777777"
            },
            {
                "id": 2,
                "phone": "66666666"
            }
        ],
        "combined": null
    }
]

预期结果是：

[
    {
        "phones": [
                    //data removed for brevity
        ],
        "phonesTwo": [
                    //data removed for brevity 
        ],
        "combined": [
            {
                "phone": "44444444"
            },
            {
                "phone": "5555555"
            },
            {
                "phone": "77777777"
            },
            {
                "phone": "77777777"
            }
        ]
    }
]

尝试使用flatmap，但卡在了这里，我应该如何继续？

employee.getPhones()
               .stream()
               .flatMap(employee.getPhonesTwo().stream()
                        .map(two -> {
                             Combined combined = new  Combined();
                              //not sure what to do here
                        })).collect(Collectors.toList());

【问题讨论】：

标签： java-8 java-stream flatmap

【解决方案1】：

class Combined {
  String phone;

  public Combined(String phone) {
    this.phone = phone;
  }
}

只需迭代两个列表并将新对象与手机添加到组合数组中

ArrayList<Combined> combined = new ArrayList<Combined>()    

for(obj in employee.getPhones()) {
  combined.add(new Combined(obj.phone))
}

for(obj in employee.getPhonesTwo()) {
  combined.add(new Combined(obj.phone))
}

System.out.println(combined)

【讨论】：