java 中怎样将2个不同对象的list 和成一个list

Posted 2023-05-07

参考技术A 合并list需要两个list的类型相同，例子如下：
List
list1
=
new
ArrayList
();
List
list2
=
new
ArrayList
();
list1.add("测");
list1.add("试");
list2.add("合");
list2.add("并");
list1.addAll(list2);

将 2 个不同对象的列表合并为一个组合对象

【中文标题】将 2 个不同对象的列表合并为一个组合对象

【英文标题】：Merge a list of 2 different objects into one combined object

【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());

【参考方案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)