Java 8:按键合并包含对象的两个列表

Question

我有两个清单:

List<Server> servers1 = new ArrayList<>();
Server s1 = new Server("MyServer");
s1.setAttribute1("Attribute1");
servers1.add(s1);

List<Server> servers2 = new ArrayList<>();
Server s2 = new Server("MyServer");
s2.setAttribute2("Attribute2");
servers2.add(s2);

servers1包含带a name和a attribute1(但不是attribute2)的服务器.
servers2包含带a name和a attribute2(但不是attribute1)的服务器.

public class Server {
   private String name;
   private String attribute1;
   private String attribute2;

   public Server(String name) { 
       this.name = name;
       this.attribute1 = "";
       this.attribute2 = "";
   }

   //Getters & Setters

}

有谁知道我如何将这两个列表合并到一个列表中,每个列表Server只包含一次(by name)但具有两个属性？

有些服务器只存在于一个或另一个列表中.最终列表应包含所有服务器.

    List<Server> servers1 = new ArrayList<>();
    Server s1 = new Server("MyServer");
    s1.setAttribute1("Attribute1");

    Server s2 = new Server("MyServer2");
    s2.setAttribute1("Attribute1.2");

    servers1.add(s1);
    servers1.add(s2);

    List<Server> servers2 = new ArrayList<>();
    Server s3 = new Server("MyServer");
    s3.setAttribute2("Attribute2");

    Server s4 = new Server("MyServer3");
    s4.setAttribute2("Attribute2.2");

    servers2.add(s3);
    servers2.add(s4);

应该导致:

[Server [name = MyServer,attribute1 = Attribute1,attribute2 = Attribute2],

服务器[name = MyServer2,attribute1 = Attribute1.2,attribute2 =]]

服务器[name = MyServer3,attribute1 =,attribute2 = Attribute2.2]]

//解决方案(大家帮忙!)

Map<String, Server> serverMap1 = Stream.concat(servers1.stream(), servers2.stream())
            .collect(Collectors.toMap(Server::getName, Function.identity(), 
            (server1, server2) -> {
                server1.setAttribute2(server2.getAttribute2()); 
                return server1; 
            }));

Answer 1

将每个列表转换为映射并合并它（我使用 Lombok 不编写样板代码）：

@Data
@NoArgsConstructor
@AllArgsConstructor
class Server {
    private String name;
    private String attribute1;
    private String attribute2;
}

public class ServerMain {

    public static void main(String[] args) {

        List<Server> servers1 = Arrays.asList(
                new Server("name1", "attr1.1", null),
                new Server("name2", "attr1.2", null));

        List<Server> servers2 = Arrays.asList(
                new Server("name1", null, "attr2.1"),
                new Server("name2", null, "attr2.2"));

        Map<String, Server> serverMap1 = servers1.stream().collect(Collectors.toMap(Server::getName, Function.identity()));
        Map<String, Server> serverMap2 = servers2.stream().collect(Collectors.toMap(Server::getName, Function.identity()));

        serverMap1.keySet().forEach(key -> serverMap1.merge(key,
                serverMap2.get(key),
                (server1, server2) -> {
                    server1.setAttribute2(server2.getAttribute2());
                    return server1;
                }));


        System.out.println(serverMap1);
    }
}