为什么Java中的所有功能都不是静态函数？以下两个示例有何不同？

Question

假设您有以下两个类，第一个是Cuboid类，第二个是描述操作的类。

public class Cuboid {
    private double length;
    private double width;
    private double height;

    public Cuboid(double length, double width, double height) {
        super();
        this.length = length;
        this.width = width;
        this.height = height;
    }

    public double getVolume() {
        return length * width * height;
    }

    public double getSurfaceArea() {
        return 2 * (length * width + length * height + width * height);
    }
}

为什么不只使用抽象类：

public class Cuboid {
    public static double getVolume(double length, double width, double height) {
        return length * width * height;
    }

    public static double getSurfaceArea(double length, double width, double height) {
        return 2 * (length * width + length * height + width * height);
    }
}

因此，如果要获取包装盒的体积，只需使用以下代码：

double boxVolume = Cuboid.getVolume(2.0, 1.0,3.0);

以下示例如何使用AWS JAVA SDK？

public class CreateVolumeBuilder {
    private AmazonEC2 ec2;
    private int size;
    private String availabilityZone;

    public CreateVolumeBuilder(AmazonEC2 ec2, int size, String availabilityZone) {
        super();
        this.ec2 = ec2;
        this.size = size;
        this.availabilityZone = availabilityZone;
    }

    public static CreateVolumeResult getVolume() {
        CreateVolumeResult createVolumeResult = ec2
                .createVolume(new CreateVolumeRequest().withAvailabilityZone(availabilityZone).withSize(size));
        return createVolumeResult;
    }
}

VS

public class CreateVolumeBuilder {
    public static CreateVolumeResult getVolume(AmazonEC2 ec2, int size, String availabilityZone) {
        CreateVolumeResult createVolumeResult= ec2.createVolume(new CreateVolumeRequest().withAvailabilityZone(availabilityZone).withSize(size));
        return createVolumeResult;
    }
}

Answer 1

您的问题简化为“为什么在编写过程式程序时为什么要进行面向对象的编程？”

OOP，函数式编程，过程

除此之外，您现在需要在某个地方存储Cuboid数据。还是可以创建一个Cuboid对象，对吗？