初学者Java：可变范围问题

我正在从我的java书中练习一些工作，我遇到了一个使用变量进行计算的方法的问题。 请注意，这是一项正在进行中的工作，我只是想让它使用circleArea方法来计算此刻的圆形区域。 这是必要的代码：

public class Geometry { public static void printMenu() { System.out.println("This is a geometry calculator\nChoose what you would like to calculate" + "\n1. Find the area of a circle\n2. Find the area of a rectangle\n3." + " Find the area of a triangle\n4. Find the circumference of a circle." + "\n5. Find the perimeter of a rectangle\n6. Find the perimeter of a triangle" + "\nEnter the number of your choice:"); } public static void circleArea(double area) { System.out.println(Math.PI*Math.pow(radius, 2)); } public static void main(String[] args) { int choice; //the user's choice double value = 0; //the value returned from the method char letter; //the Y or N from the user's decision to exit double radius; //the radius of the circle double length; //the length of the rectangle double width; //the width of the rectangle double height; //the height of the triangle double base; //the base of the triangle double side1; //the first side of the triangle double side2; //the second side of the triangle double side3; //the third side of the triangle } } 

Answer 1

请声明一个类的变量并从中调用该函数。

  public class Geometry { int choice; //the user's choice double value = 0; //the value returned from the method char letter; //the Y or N from the user's decision to exit double radius; //the radius of the circle double length; //the length of the rectangle double width; //the width of the rectangle double height; //the height of the triangle double base; //the base of the triangle double side1; //the first side of the triangle double side2; //the second side of the triangle double side3; //the third side of the triangle public static void printMenu() { System.out.println("This is a geometry calculator\nChoose what you would like to calculate" + "\n1. Find the area of a circle\n2. Find the area of a rectangle\n3." + " Find the area of a triangle\n4. Find the circumference of a circle." + "\n5. Find the perimeter of a rectangle\n6. Find the perimeter of a triangle" + "\nEnter the number of your choice:"); } public static void circleArea(double area) { System.out.println(Math.PI*Math.pow(radius, 2)); } public static void main(String[] args) { Geometry g = new Geometry(); g.printMenu(); } }