leafinsnowfield的专栏

public class TestCircleRectangle { public static void main(String[] args) { GeometricObject1 circle=new Circle4(); GeometricObject1 rectangle=new Rectangle1(2,4); displayGemotricObject1(circ

public class TestAccount { public static void main(String[] args) { Account account=new Account(1122,20000); account.setAnnualInterestRate(0.045); account.withdraw(2500); account.deposit(30

public class Account { private int id; private double balance; private double annualInterestRate; private java.util.Date date; public Account() { date=new java.util.Date(); } public Account(

public class Computer { private int size; public Computer() { System.out.println("create a computer."); } public Computer(int size) { this(); this.size=size; } }public interface