java - 迭代嵌套列表(任何深度)

Question

如何迭代嵌套列表(任何深度)？我有以下结构

Com 1
    Com 2
        Com 55
            Com 551
            Com 552
        Com 56
        Com 57
            Com 66
            Com 67
                Com 99
    Com 3
        Com 33
        Com 34
        Com 35
    Com 4
        Com 41
        Com 42
            Com 421
            Com 423

我想将数据导出到具有层次结构的 txt 文件。如何检测何时应该添加“空间”以建立层次结构？

@Entity
public class Company {
    private Long id;
    private String name;
    private List<Company> children = new ArrayList<>();


    public Company() {
    }
    
    //getters and setters
    
    public Stream<Company> flattened() {
        return Stream.concat(
                Stream.of(this),
                children.stream().flatMap(Company::flattened));
    }
}

Answer 1

假设您没有循环公司引用(因此没有子公司指向其父公司之一)，您可以像这样递归地执行此操作:

public static void print(Company company, int depth) {
        for (int i = 0; i < depth; i++) {
            System.out.print(" ");
        }
        System.out.println(company.getName());
        for (Company child : company.getChildren()) {
            print(child, depth + 1);
        }
}