接上一版“类访问另一个包类的解决方法”

 4、TestCircleRectangle.java

package chapter9; public class TestCircleRectangle { public static void main(String [] args){ Circle circle = new Circle(1); System.out.println("A circle " + circle.toString()); System.out.println(circle.getRadius()); System.out.println("The radius is " + circle.getRadius()); System.out.println("The area is " + circle.getArea()); System.out.println("The diameter is " + circle.getDiameter()); Rectangle rectangle = new Rectangle(2,4); System.out.println("/nA rectangle " + rectangle.toString()); System.out.println("The area is " + rectangle.getArea()); System.out.println("The perimeter is " + rectangle.getPerimeter()); } } package chapter9; public class TestCircleRectangle { public static void main(String [] args){ Circle circle = new Circle(1); System.out.println("A circle " + circle.toString()); System.out.println(circle.getRadius()); System.out.println("The radius is " + circle.getRadius()); System.out.println("The area is " + circle.getArea()); System.out.println("The diameter is " + circle.getDiameter()); Rectangle rectangle = new Rectangle(2,4); System.out.println("/nA rectangle " + rectangle.toString()); System.out.println("The area is " + rectangle.getArea()); System.out.println("The perimeter is " + rectangle.getPerimeter()); } } package chapter9; public class TestCircleRectangle { public static void main(String [] args){ Circle circle = new Circle(1); System.out.println("A circle " + circle.toString()); System.out.println(circle.getRadius()); System.out.println("The radius is " + circle.getRadius()); System.out.println("The area is " + circle.getArea()); System.out.println("The diameter is " + circle.getDiameter()); Rectangle rectangle = new Rectangle(2,4); System.out.println("/nA rectangle " + rectangle.toString()); System.out.println("The area is " + rectangle.getArea()); System.out.println("The perimeter is " + rectangle.getPerimeter()); } } package chapter9; public class TestCircleRectangle { public static void main(String [] args){ Circle circle = new Circle(1); System.out.println("A circle " + circle.toString()); System.out.println(circle.getRadius()); System.out.println("The radius is " + circle.getRadius()); System.out.println("The area is " + circle.getArea());package chapter9; public class TestCircleRectangle { public static void main(String [] args){ Circle circle = new Circle(1); System.out.println("A circle " + circle.toString()); System.out.println(circle.getRadius()); System.out.println("The radius is " + circle.getRadius()); System.out.println("The area is " + circle.getArea()); System.out.println("The diameter is " + circle.getDiameter()); Rectangle rectangle = new Rectangle(2,4); System.out.println("/nA rectangle " + rectangle.toString()); System.out.println("The area is " + rectangle.getArea()); System.out.println("The perimeter is " + rectangle.getPerimeter()); } } package chapter9; public class TestCircleRectangle { public static void main(String [] args){ Circle circle = new Circle(1); System.out.println("A circle " + circle.toString()); System.out.println(circle.getRadius()); System.out.println("The radius is " + circle.getRadius()); System.out.println("The area is " + circle.getArea());package chapter9; public class TestCircleRectangle { public static void main(String [] args){ Circle circle = new Circle(1); System.out.println("A circle " + circle.toString()); System.out.println(circle.getRadius()); System.out.println("The radius is " + circle.getRadius()); System.out.println("The area is " + circle.getArea()); System.out.println("The diameter is " + circle.getDiameter()); Rectangle rectangle = new Rectangle(2,4); System.out.println("/nA rectangle " + rectangle.toString()); System.out.println("The area is " + rectangle.getArea()); System.out.println("The perimeter is " + rectangle.getPerimeter()); } } package chapter9; public class TestCircleRectangle { public static void main(String [] args){ Circle circle = new Circle(1); System.out.println("A circle " + circle.toString()); System.out.println(circle.getRadius()); System.out.println("The radius is " + circle.getRadius()); System.out.println("The area is " + circle.getArea());package chapter9; public class TestCircleRectangle { public static void main(String [] args){ Circle circle = new Circle(1); System.out.println("A circle " + circle.toString()); System.out.println(circle.getRadius()); System.out.println("The radius is " + circle.getRadius()); System.out.println("The area is " + circle.getArea()); System.out.println("The diameter is " + circle.getDiameter()); Rectangle rectangle = new Rectangle(2,4); System.out.println("/nA rectangle " + rectangle.toString()); System.out.println("The area is " + rectangle.getArea()); System.out.println("The perimeter is " + rectangle.getPerimeter()); } } package chapter9; public class TestCircleRectangle { public static void main(String [] args){ Circle circle = new Circle(1); System.out.println("A circle " + circle.toString()); System.out.println(circle.getRadius()); System.out.println("The radius is " + circle.getRadius()); System.out.println("The area is " + circle.getArea());

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TestArrayList.java文件是

import chapter9.Circle; public class TestArrayList{ public static void main(String[] args){ //Create a list to store cities java.util.ArrayList cityList = new java.util.ArrayList(); //Add some cities in the list cityList.add("London"); //cityList now contains [London] cityList.add("New York"); //cityList now contains [London,New York] cityList.add("Paris"); //cityList now contains[London,New York,Paris] cityList.add("Toronto"); //cityList now contains[London,New York,Paris,Toronto] cityList.add("Hong Kong"); //cityList now contains[London,New York,Paris,Toronto,Hong Kong] cityList.add("Singapore"); //cityList now contains[London,New York,Paris,Toronto,Hong Kong,Singapore] System.out.println("List size" + cityList.size()); System.out.println("Is Toronto in the list?" + cityList.contains("Toronto")); System.out.println("The location of New York in the list? " + cityList.contains("New York")); System.out.println("Is the list empty? "+ cityList.isEmpty()); //Print false //Insert a new city at index 2 cityList.add(2,"Beijing"); //Remove a city at index 2 cityList.remove("Toronto"); cityList.remove(1); for (int i = 0;i <cityList.size();i ++) System.out.print(cityList.get(i) + " "); System.out.println(); //Create a list to store two circle java.util.ArrayList list = new java.util.ArrayList(); //Add two circle list.add(new Circle(2)); list.add( new Circle(3)); //Display the area of the first circle in the list System.out.println("The area of the circle? " + ((Circle)list.get(0)).getArea()); } }

 

 

运行正确，大家可以试试！

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