（1）创建基接口IBankAccount，包含存款方法payIn()、取款方法withdraw()、查询余额方法getBalance()。

（2）创建接口ITransferBankAccount（继承基接口IBankAccount），包含转账方法transferTo()。

（3）创建类CurrentAccount（实现基接口ITransferBankAccount），包含私有数据成员balance，并实现存款方法payIn()、取款方法withdraw()、查询余额getBalance()、银行转账方法transferTo()、重载toString()方法，返回银行当前账户中的余额。

//InterfaceInheritDemo.java

interface IBankAccount{//银行账户
	void payIn(double amount);//存款
	boolean withdraw(double amount);//取款，返回是否成功
	double getBalance();//余额
}
interface ITransferBankAccount extends IBankAccount{//转账银行账户
	boolean transferTo(IBankAccount destination,double amount);//转账
}
class CurrentAccount implements ITransferBankAccount{//当前账户
	public String name;
	private double balance;
	public CurrentAccount(String name){
		this.name=name;
	}
	@Override
	public void payIn(double amount) {
		// TODO Auto-generated method stub
		this.balance+=amount;          //存款
	}
	@Override
	public boolean withdraw(double amount) {//账户有足够的余额，则取款，并返回是否成功
		// TODO Auto-generated method stub
		if(this.balance>=amount){
			this.balance-=amount;
			return true;
		}
		System.out.println("余额不足，取款失败！");
		return false;
	}
	@Override
	public double getBalance() {//返回余额
		// TODO Auto-generated method stub
		return this.balance;
	}
	@Override
	public boolean transferTo(IBankAccount destination, double amount) {//银行转账
		// TODO Auto-generated method stub
		boolean result;
		if((result=withdraw(amount))==true)
			destination.payIn(amount);
		return result;
	}
	public String toString(){//返回银行当前账户中的余额，重写从object中继承的方法toString()
		return String.format("账户(%S):余额=%9.2f",this.name,this.balance);
	}
}
public class InterfaceInheritDemo {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		IBankAccount bankCount1=new CurrentAccount("张三");//账户1
		ITransferBankAccount bankCount2=new CurrentAccount("李四");//账户2
		bankCount1.payIn(200);//账户1，存款200
		bankCount2.payIn(500);//账户2，存款500
		bankCount2.transferTo(bankCount1, 100);//账户2转账100到账户1
		                                       //显示账户余额
		System.out.println(bankCount1.toString());
		System.out.println(bankCount2.toString());
	}

}

运行结果：

账户(张三):余额=   300.00
账户(李四):余额=   400.00

阅读更多

更多精彩内容