這個星期主要是學習了Java中類的繼承問題.繼承就是由已有的類創建新類,通過子類繼承父類的方法,實現一些功能.
下面就是老師布置作業的其中一個:
定義父類圓，通過繼承，獲得子類球、圓錐、圓柱，子類具有計算體積的功能。
1）新建文件夾Test1；
2）定義父類Circle，Circle具有保護成員變量半徑r，並提供成員方法setR、getArea和帶參數的構造函數；
3）子類球Ball具有獲得體積的成員方法getValume；
4）子類圓錐Cone、圓柱Cylinder具有私有的成員變量高high、設置高的成員方法setHigh()和獲得體積的getValume；
5）3個子類都提供帶參數的構造函數；
6）3個子類在重設半徑后，應獲得正確的體積；
7）編寫測試類進行測試
代碼:
Circle.java
package test3;
public class Circle {
public static void main(String[] args) {
// TODO Auto-generated method stub
}
protected double r;
public void setR(double r) {
this.r = r;
}
public double getArea() {
return 3.14*r*r;
}
// public Circle(double r) {
// super();
// this.r = r;
// }
public Circle() {
super();
// TODO Auto-generated constructor stub
}
}
Ball.java
package test3;
import java.util.Scanner;
public class Ball extends Circle{
public static void main(String[] args) {
// TODO Auto-generated method stub
reader = new Scanner(System.in);
Ball ball =new Ball();
double r;
System.out.println("請輸入圓的半徑：");
r = reader.nextDouble();
ball.setR(r);
System.out.println("體積：" + ball.getValumn());
}
private static Scanner reader;
public double getValumn() {
return getArea()*r*4/3;
}
public Ball() {
super();
// TODO Auto-generated constructor stub
}
}
Cone.java
package test3;
import java.util.Scanner;
public class Cone extends Circle{
// public Cone(double r) {
// super(r);
// // TODO Auto-generated constructor stub
// }
//private double valumn;
private double high;
private static Scanner reader;
public void setHigh(double high) {
this.high = high;
}
public double getValumn() {
return getArea() *high/3;
}
public Cone() {
super();
// TODO Auto-generated constructor stub
}
public static void main(String[] args) {
// TODO Auto-generated method stub
reader = new Scanner(System.in);
Cone cone = new Cone();
double high,r;
System.out.println("請輸入圓錐的高：");
high = reader.nextDouble();
System.out.println("請輸入圓錐的半徑：");
r = reader.nextDouble();
cone.setHigh(high);
cone.setR(r);
System.out.println("體積：" + cone.getValumn());
}
}
Cylinder.java
package test3;
import java.util.Scanner;
public class Cylinder extends Circle{
public static void main(String[] args) {
// TODO Auto-generated method stub
reader = new Scanner(System.in);
Cylinder cy = new Cylinder();
double r,high;
System.out.println("請輸入的高：");
high = reader.nextDouble();
System.out.println("請輸入半徑：");
r = reader.nextDouble();
cy.setHigh(high);
cy.setR(r);
System.out.println("體積：" + cy.getValumn());
}
private double high;
private static Scanner reader;
public void setHigh(double high) {
this.high = high;
}
public double getValumn() {
return getArea() *high;
}
public Cylinder() {
super();
// TODO Auto-generated constructor stub
}
}
Java中類的繼承,更多的可以查看http://www.cnblogs.com/dolphin0520/p/3803432.html,這里有詳細的介紹,我大致就是看這個學習的.
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作者：yang_tang
來源：CSDN
原文：https://blog.csdn.net/yang_tang/article/details/78070791?utm_source=copy
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