Java8流-嵌套映射到列表

您需要这样的东西：

List firstlist = new ArrayList<>();
firstlist.add(new ObjectA(3, Arrays.asList("test", "test2")));
List secOndList= new ArrayList<>();
secondList.add(new ObjectB("test", 3));

List result = firstlist.stream()
        .flatMap(a -> secondList.stream()
                .filter(b -> a.getNames().contains(b.getName()))
                .map(c -> new ObjectC(a.getId(), c.getName(), c.getAge()))
        ).collect(Collectors.toList());

如果我理解您的问题，您将有三个不同的对象，如下所示：

@Getter @Setter @AllArgsConstructor @NoArgsConstructor
public class ObjectA {
    private int id;
    private List names;
}

@Getter @Setter @AllArgsConstructor @NoArgsConstructor
public class ObjectB {
    private String name;
    private int age;
}

//And the result Object you want to get
@Getter @Setter @AllArgsConstructor @NoArgsConstructor @ToString
public class ObjectC {
    private int id;
    private String name;
    private int age;
}

此示例的输出是：

[ObjectC(id=3, name=test, age=3)]

_{对于注释，我正在使用Lombok}

您需要这样的东西：

List firstlist = new ArrayList<>();
firstlist.add(new ObjectA(3, Arrays.asList("test", "test2")));
List secOndList= new ArrayList<>();
secondList.add(new ObjectB("test", 3));

List result = firstlist.stream()
        .flatMap(a -> secondList.stream()
                .filter(b -> a.getNames().contains(b.getName()))
                .map(c -> new ObjectC(a.getId(), c.getName(), c.getAge()))
        ).collect(Collectors.toList());

如果我理解您的问题，您将有三个不同的对象，如下所示：

@Getter @Setter @AllArgsConstructor @NoArgsConstructor
public class ObjectA {
    private int id;
    private List names;
}

@Getter @Setter @AllArgsConstructor @NoArgsConstructor
public class ObjectB {
    private String name;
    private int age;
}

//And the result Object you want to get
@Getter @Setter @AllArgsConstructor @NoArgsConstructor @ToString
public class ObjectC {
    private int id;
    private String name;
    private int age;
}

此示例的输出是：

[ObjectC(id=3, name=test, age=3)]

_{对于注释，我正在使用Lombok}