5.2 实验练习

5.2.3 接口回调

interface ComputerTotalSales{
	public double totalSalesByYear();
}

class Televison implements ComputerTotalSales{
	public double totalSalesByYear(){
		return 10000;
	}
}

class Computer implements ComputerTotalSales{
	public double totalSalesByYear(){
		return 20000;
	}
}

class Mobile implements ComputerTotalSales{
	public double totalSalesByYear(){
		return 150000;
	}
}

class Shop{
	ComputerTotalSales[]goods;
	double totalSales=0;
	Shop(ComputerTotalSales[]goods){
		this.goods=goods;
	}
	public double giveTotalSales(){
		totalSales=0;
		for(int i=0;i<goods.length;i++){
			totalSales=totalSales+goods[i].totalSalesByYear();
		}
		return totalSales;
	}
}

public class HappySale{
	public static void main(String args[]){
		ComputerTotalSales[]goods=new ComputerTotalSales[50];
		for(int i=0;i<goods.length;i++){
			if(i%3==0){
				goods[i]=new Televison();
			}
			else if(i%3==1){
				goods[i]=new Computer();
			}
			else if(i%3==2){
				goods[i]=new Mobile();
			}
		}
		Shop shop=new Shop(goods);
		System.out.println("商品年销售额："+shop.giveTotalSales());
	}
}

5.2.4异常处理

class NoLowerLetter extends Exception{
	public void print(){
		System.out.printf("%c",'#');
	}
}

class NoDigit extends Exception{
	public void print(){
		System.out.printf("%c",'*');
	}
}

class People{
	void printLetter(char c) throws NoLowerLetter{
		if(c<'a'||c>'z'){
			NoLowerLetter noLowerLetter=new NoLowerLetter();
			throw(noLowerLetter);
		}
		else{
			System.out.print(c);
		}
	}
	void printDigit(char c) throws NoDigit{
		if(c<'1'||c>'9'){
			NoDigit noDigit=new NoDigit();
			throw (noDigit);
		}
		else{
			System.out.print(c);
		}
	}
}

public class ExceptionExample{
	public static void main(String args[]){
		People people=new People();
		for(int i=0;i<128;i++){
			try{
				people.printLetter((char)i);
			}
			catch(NoLowerLetter e){
				e.print();
			}
		}
		for(int i=0;i<128;i++){
			try{
				people.printDigit((char)i);
			}
			catch(NoDigit e){
				e.print();
			}
		}
	}
}