为什么我构造器中初始化lenght为1，但是我get lenght却为0

Question

public class Cylinder extends Circle{
    private double length;
    
    public Cylinder() {
        double length = 1.0;
    }
    public void setLength(double length) {
        this.length = length;
    }
    public double getLength() {
        return length;
    }
    public double findVolume() {
        return findArea()*getLength();
    }
}

Answer 1

public Cylinder() {
double length = 1.0;
}
你这相当于在函数内定义了一个临时变量，而不是给类的成员变量length赋值，修改如下。

 
public class Cylinder extends Circle{
    private double length;
    
    public Cylinder() {
        length = 1.0;
    }
    public void setLength(double length) {
        length = length;
    }
    public double getLength() {
        return length;
    }
    public double findVolume() {
        return findArea()*getLength();
    }
}