java 中的构造函数链接有何意义以及如何将其与 tostring() 结合使用？

Question

所以我知道如何使用它，它如何 works.The 质疑在现实生活场景中有什么意义。想象一下在没有 toString() 覆盖的情况下创建 class。那么如果不能正确显示，class 有什么意义呢？？

请尽量不要解释构造函数链是如何工作的或类似的东西。我知道它是如何工作的。我想知道现实生活中有人这样做吗因为没有 toString() 覆盖我不明白这一点

   public class ConstructorChaining {

        String a;
        int b;
        int c;
        int d;
        int e;

        public ConstructorChaining() {
            this("");
        }


        public ConstructorChaining(String a) {
            this(a, 0);

        }

        public ConstructorChaining(String a, int b) {
            this(a, b, 0);

        }

        public ConstructorChaining(String a, int b, int c) {
            this(a, b, c, 0);

        }

        public ConstructorChaining(String a, int b, int c, int d) {
            this(a, b, c, d, 0);

        }

        public ConstructorChaining(String a, int b, int c, int d, int e) {
            this.a = a;
            this.b = b;
            this.c = c;
            this.d = d;
            this.e = e;
        }

    }

想象一下我创建了一个对象

ConstructorChaining constructorChaining=new ConstructorChaining("name");

并尝试打印它

System.out.println(constructorChaining);

我如何为此实现toString()

Answer 1

只需执行此操作，使用根据您调用的构造函数设置不同的字段：

public class ConstructorChaining {

   String a;
   int b;
  //This value is different for each constructor, so you can control your
  //toString implementation
  String asString;

public ConstructorChaining() {
            this("");
        }


        public ConstructorChaining(String a) {
            this(a, 0, a + "");

        }

        public ConstructorChaining(String a, int b) {
            this(a, b, 0, a + "" + b);

        }

        private ConstructorChaining(String a, int b, String asString) {
            this.a = a;
            this.b = b;
            this.asString = asString;
        }

@Override
public String toString() {
  return "Overriden toString, asString = " + asString;
}

Answer 2

 public class ConstructorChaining {

    String a;
    int b;
    int c;
    int d;
    int e;

    public ConstructorChaining() {
        this("");
    }


    public ConstructorChaining(String a) {
        this(a, 0);

    }

    public ConstructorChaining(String a, int b) {
        this(a, b, 0);

    }

    public ConstructorChaining(String a, int b, int c) {
        this(a, b, c, 0);

    }

    public ConstructorChaining(String a, int b, int c, int d) {
        this(a, b, c, d, 0);

    }

    public ConstructorChaining(String a, int b, int c, int d, int e) {
        this.a = a;
        this.b = b;
        this.c = c;
        this.d = d;
        this.e = e;
    }

    @Override 
    public String toString() {
        return "ConstructorChaining={a=" + a + ", b=" + b + ", c=" + c + ", d=" + d + ", e=" + e;
    }
}

看看你的朋友怎么说的，contractors和toString重写方法没有关系。

所有基本类型都已初始化为 0，因此您无需关心值是否存在。

java 中的构造函数链接有何意义以及如何将其与 tostring() 结合使用？

What is the point of constructor chaining in java and how to combine it with tostring()?

java

constructor

constructor-chaining