避免在 toString 方法中递归 [英] Avoiding recursion in toString method

问题描述

这是我在 Java 练习中遇到的巨大问题.所以，我们有这个:

this is my huge mindblowing problem with a Java exercise. So, we've got this:

public class CyclicEmployee {
    private int age;
    private String name;
    private CyclicEmployee boss;
    private List<CyclicEmployee> subordinate
}

我们的目标是通过切割可能导致递归无穷大的字段来覆盖 toString 方法.最后，它应该看起来像一个带有姓名、年龄、老板和下属的印刷品.

and our goal is to overwrite toString method by cutting fields which may lead to recursive infinity. Finally it's supposed to look like a printed object with a name, age, boss and subordinate.

Employee[age=30,name='Mike',boss=Employee[age=45,name='Ann'], subordinate=[Employee[age=25,name='Jimmy']]]

好吧，我试过了，发现我不知道如何处理 toString 覆盖:

Well, I tried and found that i have no clue how to deal with toString overriding:

import java.util.ArrayList;
import java.util.List;

public class CyclicEmployee {
    private int age;
    private String name;
    private CyclicEmployee boss;
    private List<CyclicEmployee> subordinate ;

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

public static void main(String[] args) {
  CyclicEmployee Mike = new CyclicEmployee(33,"Mike");
  Mike.boss = new CyclicEmployee(44,"Ann");
  Mike.subordinate = new ArrayList<CyclicEmployee>();
  Mike.subordinate.add(new CyclicEmployee(24,"Jim"));
    System.out.println(Mike.toString());
}

@Override
public String toString() {
    return "CyclicEmployee{" +
            "age=" + age +
            ", name='" + name + '\'' +
            ", boss=" + boss +
            ", subordinate=" + subordinate +
            '}';
    }

}CyclicEmployee{age=33, name='Mike', boss=CyclicEmployee{age=44, name='Ann', boss=null, subordinate=null}, subordinate=[CyclicEmployee{age=24, name='Jim', boss=null, subordinate=null}]}

好像我应该把这里所有的空"字段都删掉，但我找不到出路.

It seems like I should cut all the "null" fields here, but I can't find the way out.

推荐答案

如果我理解正确，您不希望打印空的 CyclicEmployee 对象.您可以检查 boss 和 subordinates 是否为空，然后在 toString() 中跳过它们.因为它们都是相同的类型，所以这个方法对它们都有效.

If I understand correctly, you do not want to print null CyclicEmployee objects. You can check if boss and subordinates are null and then if they are skip them in toString(). Since all of them are same type, this method will work for all of them.

@Override
public String toString() {

String str = "";
str = "CyclicEmployee{" +
    "age=" + age +
    ", name='" + name + '\'';
if (boss != null) {
  str += ", boss=" + boss;
}
if (subordinate.size() != 0) {
  str += ", subordinate=" + subordinate;
}
  str += '}';
return str;
}

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