System.out.println("购买物品\t" + "单价\t" + "个数\t" + "金额");

Scanner in = new Scanner(System.in);

String String1 ;

int a = 0;

int b = 0;

int c = 0;

double sum=0;

do {

System.out.println("请选择你购买的物品");

String aString = in.next();

if (aString.equals("上衣")) {

System.out.println("请选择购买的数量：");

int num1 = in.nextInt();

a = num1 * 245;

System.out.println("上衣的金额为" + a);

} else if (aString.equals("网球鞋")) {

System.out.println("请选择购买的数量：");

int num2 = in.nextInt();

b = 570 * num2;

System.out.println("网球鞋的金额为：" + b);

} else if (aString.equals("网球拍")) {

System.out.println("请选择购买的数量：");

int num3 = in.nextInt();

c = 320 * num3;

System.out.println("网球拍的金额为：" + c);

} else {

System.out.println("输入错误，请重新输入。");

}

System.out.println("是否继续输入Y/N");

String1 = in.next();

} while (String1.equals("Y"));

sum=a+b+c;

System.out.println("总金额为：" +sum );

}

}

int a = 0;

int b = 0;

int c = 0;

这一部分可以简化为int a=0；

再把sum=sum+a;放进do-while循环体里面，就可以自动计算总价了。