java - 我们是否必须从其子类中的类 Object 调用默认构造函数

Question

如果我在类中调用或不调用Object的默认构造函数，有什么区别吗:

public class BankCustomer {
    private Person owner;

    public BankCustomer(Person owner) {
        this.owner = owner;
    }
}

或者

public class BankCustomer {
    private Person owner;

    public BankCustomer(Person owner) {
        super();
        this.owner = owner;
    }

}

Answer 1

没有什么区别。如果您没有显式调用父类(super class)构造函数，那么 Java 将插入对默认父类(super class)构造函数的隐式调用作为构造函数中的第一个语句。

JLS, Section 8.8.7状态:

If a constructor body does not begin with an explicit constructor invocation and the constructor being declared is not part of the primordial class Object, then the constructor body implicitly begins with a superclass constructor invocation "super();", an invocation of the constructor of its direct superclass that takes no arguments.

就你的情况而言，这是完全没有必要的。虽然将 super(); 保留在那里没有什么坏处，但我会删除它。