/*程序功能:输入圆的半径,计算出面积。*/public class CircleArea{
final static double Pi=3.14159;
public static void main(String args[]) throws java.io.IOException{ double r;
System.out.print("请输入圆半径r="); r=(double)System.in.read();
System.in.skip(2);
System.out.println("圆半径是:"+r+",圆面积是:"+area(r)); }
static double area(double r){ return(Pi*r*r);
}
} 问题(1)为什么输入1以后,显示输出的是ASCII值?我输入1,按回车,输出显示半径是49(1的ASCII值)。(2)这里为什么不能用throws IOException 抛出异常?
final static double Pi=3.14159;
public static void main(String args[]) throws java.io.IOException{ double r;
System.out.print("请输入圆半径r="); r=(double)System.in.read();
System.in.skip(2);
System.out.println("圆半径是:"+r+",圆面积是:"+area(r)); }
static double area(double r){ return(Pi*r*r);
}
} 问题(1)为什么输入1以后,显示输出的是ASCII值?我输入1,按回车,输出显示半径是49(1的ASCII值)。(2)这里为什么不能用throws IOException 抛出异常?
界面上read只能读到char或者是string,你输入的是1,就是char(1),转换成int就是49.
try{
double r; //用整形呗,面积可以用double
System.out.print("请输入圆半径r="); r=(double)System.in.read();
System.in.skip(2);
System.out.println("圆半径是:"+r+",圆面积是:"+area(r));
}catch(Exeception e){
System.out.print(e.P...);你懂的
}
public class CircleArea{
final static double Pi=3.14159;
public static void main(String args[]){
try{
double r;
BufferedReader reader=new BufferedReader(new InputStreamReader(System.in));
System.out.print("请输入圆半径r=");
String str=reader.readLine(); //获取字符串
r = Double.parseDouble(str);
System.out.println("圆半径是:"+r+",圆面积是:"+area(r));
}catch(Exception){
e.printstacktrace();
}
}
static double area(double r){ return(Pi*r*r);
}
} 写成这样就没问题了。。你随便输入数字
final static double Pi=3.14159;
public static void main(String args[]){
try{
double r;
System.out.print("请输入圆半径r=");
Scanner scanner=new Scanner(System.in);
int r=scanner.nextInt(); //获取整数值
System.out.println("圆半径是:"+r+",圆面积是:"+area(r));
}catch(Exception){
e.printstacktrace();
}
}
static double area(double r){ return(Pi*r*r);
}
}
或者也可以写成这样