之前因未指明问题而受到责骂。承诺这次做得更好。
出于某种原因，当我输入0时循环不会停止，而是继续再次打印出main方法。我该如何解决？我无法发现它有什么问题，因为其他一切都顺利进行。
另外，我想使用Switch而不是If，但我不断收到重复变量错误。为什么？
import java.util.Scanner;
public class FindArea
{
// side is only input provided to cube. Area of the cube is returned
public static double cube (double side)
{
double Area;
return Area = 6 * side * side;
}
// radius is only input provided to sphere. Area of the sphere is returned
public static double sphere (double radius)
{
double Area;
return Area = 4 * 3.14 * radius * radius;
}
// radius and height are the only inputs provided to cylinder.
// Area of the cylinder is returned
public static double cylinder (double radius, double height)
{
double Area;
return Area = 2 * 3.14 * radius * height + 2 * 3.14 * radius * radius;
}
// outerR and innerR are the only inputs provided to doughnut.
// Area of the doughnut is returned
public static double doughnut (double outerR, double innerR)
{
double Area;
return Area = (2 * 3.14 * innerR) * (2 * 3.14 * outerR);
}
public static void main(String[] args)
{
int n = 4;
Scanner input = new Scanner(System.in);
System.out.println("Enter 1 for Cube, 2 for Sphere, 3 for Cylinder, 4 for Doughnut");
do
{
n = input.nextInt();
if ( n<0 || n>4) {
System.out.println("Invalid");
}
if(n == 1) {
System.out.print("Enter side measurement of cube: ");
double side = input.nextDouble();
double Area = cube(side);
System.out.println("The area of the cube is: " + Area);
}
if (n == 2) {
System.out.print("Enter radius measurement of sphere: ");
double radius = input.nextDouble();
double Area = sphere (radius);
System.out.println("The area of the sphere is: " + Area);
}
if (n == 3) {
System.out.print("Enter radius measurement of cylinder: ");
double radius = input.nextDouble();
System.out.print("Enter height measurement of cylinder: ");
double height = input.nextDouble();
double Area = cylinder (radius, height);
System.out.println("The area of the cylinder is: " + Area);
}
if (n == 4) {
System.out.print("Enter inner radius: ");
double innerR = input.nextDouble();
System.out.print("Enter outer radius: ");
double outerR = input.nextDouble();
double Area = doughnut (outerR, innerR);
System.out.println("The area of the donut is: " + Area);
}
System.out.println("--------");
System.out.println("Enter 1 for Cube, 2 for Sphere, 3 for Cylinder, 4 for Doughnut");
System.out.println("Or enter 0 to exit");
} while (n != 0);
System.exit(1);
}
}
答案 0 :(得分：2)
它再次打印输出，因为直到Do-While循环结束才进行比较。
它会检查除0以外的所有n个案例，并打印输出，无论如何。
我认为你所寻求的更是如此：
n = input.nextInt();
if(n!=0){
if ( n<0 || n>4) {
System.out.println("Invalid");
}
if(n == 1) {
System.out.print("Enter side measurement of cube: ");
double side = input.nextDouble();
double Area = cube(side);
System.out.println("The area of the cube is: " + Area);
}
if (n == 2) {
System.out.print("Enter radius measurement of sphere: ");
double radius = input.nextDouble();
double Area = sphere (radius);
System.out.println("The area of the sphere is: " + Area);
}
if (n == 3) {
System.out.print("Enter radius measurement of cylinder: ");
double radius = input.nextDouble();
System.out.print("Enter height measurement of cylinder: ");
double height = input.nextDouble();
double Area = cylinder (radius, height);
System.out.println("The area of the cylinder is: " + Area);
}
if (n == 4) {
System.out.print("Enter inner radius: ");
double innerR = input.nextDouble();
System.out.print("Enter outer radius: ");
double outerR = input.nextDouble();
double Area = doughnut (outerR, innerR);
System.out.println("The area of the donut is: " + Area);
}
System.out.println("--------");
System.out.println("Enter 1 for Cube, 2 for Sphere, 3 for Cylinder, 4 for Doughnut");
System.out.println("Or enter 0 to exit");
}
请注意n!=0
另外看看switch-case的使用，一旦你学会了这些比较，这些比较不仅会更快，而且很容易理解
答案 1 :(得分：0)
您可以尝试使用开关盒 -
public static void main(String[] args)
{
int n = 4;
Scanner input = new Scanner(System.in);
System.out.println("Enter 1 for Cube, 2 for Sphere, 3 for Cylinder, 4 for Doughnut");
System.out.println("Or enter 0 to exit");
n = input.nextInt();
if ( n<0 || n>4) {
System.out.println("Invalid");
}
else{
switch(n){
case 0:{
System.out.println("You enter 0 to exit");
break;
}
case 1:{
System.out.print("Enter side measurement of cube: ");
double side = input.nextDouble();
double Area = cube(side);
System.out.println("The area of the cube is: " + Area);
break;
}
case 2:{
System.out.print("Enter radius measurement of sphere: ");
double radius = input.nextDouble();
double Area = sphere (radius);
System.out.println("The area of the sphere is: " + Area);
break;
}
case 3: {
System.out.print("Enter radius measurement of cylinder: ");
double radius = input.nextDouble();
System.out.print("Enter height measurement of cylinder: ");
double height = input.nextDouble();
double Area = cylinder (radius, height);
System.out.println("The area of the cylinder is: " + Area);
break;
}
case 4:{
System.out.print("Enter inner radius: ");
double innerR = input.nextDouble();
System.out.print("Enter outer radius: ");
double outerR = input.nextDouble();
double Area = doughnut (outerR, innerR);
System.out.println("The area of the donut is: " + Area);
break;
}
}
}
}
答案 2 :(得分：-1)
我使用开关盒完成了这个。非常简单
public class FindArea {
// side is only input provided to cube. Area of the cube is returned
public static double cube(double side) {
double Area;
return Area = 6 * side * side;
}
// radius is only input provided to sphere. Area of the sphere is returned
public static double sphere(double radius) {
double Area;
return Area = 4 * 3.14 * radius * radius;
}
// radius and height are the only inputs provided to cylinder.
// Area of the cylinder is returned
public static double cylinder(double radius, double height) {
double Area;
return Area = 2 * 3.14 * radius * height + 2 * 3.14 * radius * radius;
}
// outerR and innerR are the only inputs provided to doughnut.
// Area of the doughnut is returned
public static double doughnut(double outerR, double innerR) {
double Area;
return Area = (2 * 3.14 * innerR) * (2 * 3.14 * outerR);
}
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out
.println("Enter 1 for Cube, 2 for Sphere, 3 for Cylinder, 4 for Doughnut, Or enter 0 to exit ");
int n = 0;
double side = 0;
double Area = 0;
double radius = 0;
double height = 0;
n = input.nextInt();
switch (n) {
case 0:
System.out.println("Exit");
System.exit(1);
break;
case 1:
System.out.print("Enter side measurement of cube: ");
side = input.nextDouble();
Area = cube(side);
System.out.println("The area of the cube is: " + Area);
break;
case 2:
System.out.print("Enter radius measurement of sphere: ");
radius = input.nextDouble();
Area = sphere(radius);
System.out.println("The area of the sphere is: " + Area);
break;
case 3:
System.out.print("Enter radius measurement of cylinder: ");
radius = input.nextDouble();
System.out.print("Enter height measurement of cylinder: ");
height = input.nextDouble();
Area = cylinder(radius, height);
System.out.println("The area of the cylinder is: " + Area);
break;
case 4:
System.out.print("Enter inner radius: ");
double innerR = input.nextDouble();
System.out.print("Enter outer radius: ");
double outerR = input.nextDouble();
Area = doughnut(outerR, innerR);
System.out.println("The area of the donut is: " + Area);
break;
default:
System.out.println("--------");
System.out.println("Invalid option selected");
System.out.println("--------");
System.out
.println("Enter 1 for Cube, 2 for Sphere, 3 for Cylinder, 4 for Doughnut");
System.out.println("Or enter 0 to exit");
n = input.nextInt();
break;
}
}
}