java - Java中如何将Object的属性值转换为数组？

Question

假设我有一个对象列表，例如:-

[id = 1, age = 34, name = "abc"]
[id = 2, age = 34, name = "xyz"]
[id = 3, age = 34, name = "mno"]

然后我需要将它们转换为:-

[1], [34], [abc],
[2], [34], [xyz],
[3], [34], [mno]

Answer 1

在这种情况下，您可以使用 map 的流和 flatMap方法:

public static void main(String[] args) {
    MyClass obj = new MyClass(1, 50, "John");
    MyClass obj2 = new MyClass(2, 30, "Michał");
    List<MyClass> list = Arrays.asList(obj, obj2);
    List<Object> all = list.stream()
            .map(o -> Arrays.asList(o.getId(), o.getAge(), o.getName()))
            .flatMap(Collection::stream)
            .collect(Collectors.toList());

    all.forEach(element -> System.out.println(element));
}

public static class MyClass {
    private final int id;
    private final int age;
    private final String name;

    public MyClass(int id, int age, String name) {
        this.id = id;
        this.age = age;
        this.name = name;
    }

    public int getId() { return id; }
    public int getAge() { return age; }
    public String getName() { return name; }
}