Question

JAVA语言程序设计两道练习题。谢谢！

1、创建Person接口(即“人”)，它有setData()和getData()方法对“人”属性name、sex和birthday赋值和获得这些属性组成的字符串信息。创建类Student实现Person接口，并对自己的“学生”属性的成员变量sID、speciality设置值和获得它们值所组成的字符串信息。
2、编写程序,求柱体的体积:
（1）、为柱体的底面设计一个接口Geometry，包含计算面积的方法getArea();
（2）、为柱体设计类pillar，要求：
a)有两个成员变量，底面和高度。底面是任何可以计算面积的几何形状。
b)实现构造方法，对成员变量赋值。
c)包含成员方法，计算柱体pillar的体积。
（3）、编写测试类圆形类、矩形类实现Geometry接口，编写测试类Test，分别用圆形、矩形作为柱体的底面，并计算其体积。

Answer 1

第一题有问题：1、创建Person接口(即“人”)，它有setData()和getData()方法对“人”属性name、sex和birthday赋值和获得这些属性组成的字符串信息。
问题是：你说要创建一个人（接口），然后里面有方法对人的属性进行赋值？这怎么可能呢，接口是没有成员变量（属性）的，怎么能赋值？接口里只能有常量。

第二题可以答一下：
package pillar;
public class Pillar { private Geometry buttom;
private double height;
public Pillar() {
// TODO Auto-generated constructor stub
}
public Pillar(Geometry button,double height){
this.buttom = button;
this.height = height;
}
public double getVolume(){
return this.buttom.getArea()*height;
}
public Geometry getButtom() {
return buttom;
}
public void setButtom(Geometry buttom) {
this.buttom = buttom;
}
public double getHeight() {
return height;
}
public void setHeight(double height) {
this.height = height;
}

}
------------------------------------------------类分割线---------------------------------------------------------
package pillar;
public interface Geometry { double getArea();
}
------------------------------------------------类分割线---------------------------------------------------------
package pillar;
public class Circle implements Geometry { private double r;
public Circle() {
// TODO Auto-generated constructor stub
}

public Circle(double r) {
this.r = r;
}

public double getArea() { return Math.PI*r*r;
}
public double getR() {
return r;
}
public void setR(double r) {
this.r = r;
}

}
------------------------------------------------类分割线---------------------------------------------------------
package pillar;
public class Rectangle implements Geometry { private double width;
private double height;

public Rectangle() {
// TODO Auto-generated constructor stub
}

public Rectangle(double width, double height) {
this.width = width;
this.height = height;
}

public double getArea() { return this.width*this.height;
}
public double getWidth() {
return width;
}
public void setWidth(double width) {
this.width = width;
}
public double getHeight() {
return height;
}
public void setHeight(double height) {
this.height = height;
}

}
------------------------------------------------类分割线---------------------------------------------------------
package pillar;
public class TestPillar {
/** * @param args
*/
public static void main(String[] args) {
Circle c = new Circle(5);
Rectangle r = new Rectangle(3,4);
Pillar p1 = new Pillar(c,6);
Pillar p2 = new Pillar(r,6);
System.out.println("圆的体积："+p1.getVolume()+"\t矩形的体积："+p2.getVolume());
}

}

Answer 2

第一题

Person接口

import java.util.Date;
public interface Person {
    public void setData(String sID, String speciality, String name, String sex, Date birthday);
    public String getData();
                           
}

Student实现类

import java.util.Date;
public class Student implements Person {
    private String sID;
    private String speciality;
    private String name;
    private String sex;
    private Date birthday;
       
    @Override
    public void setData(String sID, String speciality, String name, String sex,
            Date birthday) {
        this.sID = sID;
        this.speciality = speciality;
        this.name = name;
        this.sex = sex;
        this.birthday = birthday;
    }
    @Override
    public String getData() {
        return "Student [sID=" + sID + ", speciality=" + speciality + ", name="
                + name + ", sex=" + sex + ", birthday=" + birthday + "]";
    }
       
}

Answer 3

java书上都有的