java - 基类构造函数被调用但不应该被调用

Question

我收到一条错误消息:

DerivedClass.java:6: error: constructor BaseClass in class BaseClass cannot be applied to given types;
    DerivedClass(String d) {
                           ^
  required: String
  found: no arguments
  reason: actual and formal argument lists differ in length
1 error

这是我的代码:

class BaseClass {
    BaseClass(String f) {
       System.out.println(f);
       System.out.println("BaseClass time");
    }
}
public class DerivedClass extends BaseClass {
    DerivedClass() {
        super("You did not pass an argument to your object.");
        System.out.println("It's DerivedClass time");
    }
    DerivedClass(String d) {
        System.out.println("Hey look, an argument");
        System.out.println(d);
        System.out.println("It's DerivedClass time");
    }
    public static void main(String[] args) {
        DerivedClass defauld = new DerivedClass();
        DerivedClass custom = new DerivedClass("Ayyyyy");
    }
}

做什么？我觉得没有理由让它运行失败。据我所知，DerivedClass 中允许您传递字符串的构造函数的格式正确。

Answer 1

问题是，如果您不显式执行此操作，则在构造 DerivedClass 时，编译器将调用不带参数的 super() 。修复方法很简单:

DerivedClass(String d) {
     super(d);
     // rest of your code
}

有关更多信息，您可以阅读Java Language Specification, Section 12.4.2 - Detailed Initialization Procedure