小编Oma*_*r D的帖子

下面有这个输出.

Hello World!
main.ConstructedDerivedClass:6.0
main.ConstructedDerivedClass:6.0

public class ConstructedDerivedClass extends ConstructedBase {

    private static final double version = 6.0;

    public static void main(String[] args) {

        System.out.println("Hello World!");

        ConstructedDerivedClass derivedClass = new ConstructedDerivedClass();
    }

    public ConstructedDerivedClass() {
        showMyAttributes();
    }

    @Override
    protected void showMyAttributes() {
        System.out.println(this.getClass().getName() + ":" + version);
    }  
}

public class ConstructedBase {

    private static final double version = 15.0;

    public ConstructedBase() {
        showMyAttributes();
    }

    protected void showMyAttributes() {
        System.out.println(this.getClass().getName() + ":" + version);
    }
}

我希望它只显示一行,即子类的类(ConstructedDerivedClass).但它反而打印两次.我知道一般你应该避免从构造函数中调用overriden方法,但我想亲眼看看它是如何工作的.

实际上,我知道为什么版本在两行上都是'6.0' - 因为字段被声明为静态,当然静态字段首先被初始化.但仍然不明白为什么两行. …