类访问另一个包类的解决方法_如何访问包外的类-优快云博客

本文介绍了chapter9包中四个核心类的设计与实现：Circle、GeometricObject、Rectangle及TestCircleRectangle。Circle类作为GeometricObject的子类，提供了计算圆的面积、直径等方法；Rectangle类同样继承自GeometricObject，实现了矩形的相关属性与操作。

如果你的一个单独的类，想使用一个包中的类(比如要用到包chapter9中的类Circle（此类要是public才行，因为是protected或者private类无法访问），解决方法：

在你的单独的类中加入：import chapter.Circle;

chapter9包中有四个类Circle.java、GeometricObject.java、Rectangle.java、TestCircleRectangle.java

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1、Circle.javapackage chapter9; public class Circle extends GeometricObject{ private double radius; public Circle(){ } public Circle(double radius){ this.radius = radius; } /**Return radius*/ public double getRadius(){ return radius; } /**Set a new radius*/ public void setRadius (double radius){ this.radius = radius; } /**Return area*/ public double getArea(){ return radius * radius * Math.PI; } /**Retrun diameter*/ public double getDiameter(){ return 2 * radius; } /**Return perimeter*/ public double getPerimeter(){ return 2 * radius * Math.PI; } /**Print the Circle info*/ public void printCircle(){ System.out.println("The circle is created " + getDateCreated() + " and the radius is " + radius); } } package chapter9; public class Circle extends GeometricObject{ private double radius; public Circle(){ } public Circle(double radius){ this.radius = radius; } /**Return radius*/ public double getRadius(){ return radius; } /**Set a new radius*/ public void setRadius (double radius){ this.radius = radius; } /**Return area*/ public double getArea(){ return radius * radius * Math.PI; } /**Retrun diameter*/ public double getDiameter(){ return 2 * radius; } /**Return perimeter*/ public double getPerimeter(){ return 2 * radius * Math.PI; } /**Print the Circle info*/ public void printCircle(){ System.out.println("The circle is created " + getDateCreated() + " and the radius is " + radius); } } package chapter9; public class Circle extends GeometricObject{ private double radius; public Circle(){ } public Circle(double radius){ this.radius = radius; } /**Return radius*/ public double getRadius(){ return radius; } /**Set a new radius*/ public void setRadius (double radius){ this.radius = radius; } /**Return area*/ public double getArea(){ return radius * radius * Math.PI; } /**Retrun diameter*/ public double getDiameter(){ return 2 * radius; } /**Return perimeter*/ public double getPerimeter(){ return 2 * radius * Math.PI; } /**Print the Circle info*/ public void printCircle(){ System.out.println("The circle is created " + getDateCreated() + " and the radius is " + radius); } } package chapter9; public class Circle extends GeometricObject{ private double radius; public Circle(){ } public Circle(double radius){ this.radius = radius; } /**Return radius*/ public double getRadius(){ return radi

2、GeometricObject.java

package chapter9; public class GeometricObject{ private String color = "whiter"; private boolean filled; private java.util.Date dateCreated; /**constuct a default geometric object*/ public GeometricObject() { dateCreated = new java.util.Date(); } /**Return color */ public String getColor(){ return color; } /**set a new color */ public void setColor(String color){ this.color = color; } /**Return filled.Since filled is boolean*/ public boolean isFilled(){ return filled; } /**Set a new filled*/ public void setFilled(boolean filled){ this.filled = filled; } /**Get dateCreated*/ public java.util.Date getDateCreated(){ return dateCreated; } /**Return a string represention of this object*/ public String toString(){ return "created on " + dateCreated + "/ncolor: " + color + " and filled" + filled; } }

3、Rectangle.java

package chapter9; public class Rectangle extends GeometricObject{ private double width; private double height; public Rectangle(){ } public Rectangle (double width,double height){ this.width = width; this.height = height; } /**Return width*/ public double getWidth(){ return width; } /**Set a new width*/ public void setWidth(double width){ this.width = width; } /**Return height*/ public double getHeight(){ return height; } /**Set a new height*/ public void setHeight(double height){ this.height = height; } /**Return area*/ public double getArea (){ return width * height; } /**Return perimeter*/ public double getPerimeter(){ return 2 * (width + height); } } package chapter9; public class Rectangle extends GeometricObject{ private double width; private double height; public Rectangle(){ } public Rectangle (double width,double height){ this.width = width; this.height = height; } /**Return width*/ public double getWidth(){ return width; } /**Set a new width*/ public void setWidth(double width){ this.width = width; } /**Return height*/ public double getHeight(){ return height; } /**Set a new height*/ public void setHeight(double height){ this.height = height; } /**Return area*/ public double getArea (){ return width * height; } /**Return perimeter*/ public double getPerimeter(){ return 2 * (width + height); } } package chapter9; public class Rectangle extends GeometricObject{ private double width; private double height; public Rectangle(){ } public Rectangle (double width,double height){ this.width = width; this.height = height; } /**Return width*/ public double getWidth(){ return width; } /**Set a new width*/ public void setWidth(double width){ this.width = width; } /**Return height*/ public double getHeight(){ return height; } /**Set a new height*/ public void setHeight(double height){ this.height = height; } /**Return area*/ public double getArea (){ return width * height; } /**Return perimeter*/ public double getPerimeter(){ return 2 * (width + height); } } package chapter9; public class Rectangle extends GeometricObject{ private double width; private double height; public Rectangle(){ } public Rectangle (double width,double height){ this.width = width; this.height = height; } /**Return width*/ public double getWidth()package chapter9; public class Rectangle extends GeometricObject{ private double width; private double height; public Rectangle(){ } public Rectangle (double width,double height){ this.width = width; this.height = height; } /**Return width*/ public double getWidth(){ return width; } /**Set a new width*/ public void setWidth(double width){ this.width = width; } /**Return height*/ public double getHeight(){ return height; } /**Set a new height*/ public void setHeight(double height){ this.height = height; } /**Return area*/ public double getArea (){ return width * height; } /**Return perimeter*/ public double getPerimeter(){ return 2 * (width + height); } } package chapter9; public class Rectangle extends GeometricObject{ private double width; private double height; public Rectangle(){ } public Rectangle (double width,double height){ this.width = width; this.height = height; } /**Return width*/ public double getWidth()