Methods) Area Calculator

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        while (true) {
            System.out.println("-=-=-=-=-=-=-=-=-=-=-=-=-=-=-\n");
            System.out.println("1) Triangle");
            System.out.println("2) Rectangle");
            System.out.println("3) Square");
            System.out.println("4) Circle");
            System.out.println("5) Quit");

            System.out.print("Please enter your shape selection: ");
            Scanner keyboard = new Scanner(System.in);
            int shapeOption = keyboard.nextInt();


            if (shapeOption == 1) {
                System.out.print("\nBase: ");
                Scanner keyboard2 = new Scanner(System.in);
                int base = keyboard2.nextInt();
                System.out.print("Height: ");
                Scanner keyboard3 = new Scanner(System.in);
                int height = keyboard3.nextInt();

                System.out.println("\nThe area is: " + area_triangle(base, height) + " square units");

            } else if (shapeOption == 2) {
                System.out.print("\nLength: ");
                Scanner keyboard4 = new Scanner(System.in);
                int length = keyboard4.nextInt();
                System.out.print("Width: ");
                Scanner keyboard5 = new Scanner(System.in);
                int width = keyboard5.nextInt();

                System.out.println("\nThe area is: " + area_rectangle(length, width) + " square units");

            } else if (shapeOption == 3) {
                System.out.print("\nSide length: ");
                Scanner keyboard6 = new Scanner(System.in);
                int side_length = keyboard6.nextInt();

                System.out.println("\nThe area is: " + area_square(side_length) + " square units");

            } else if (shapeOption == 4) {
                System.out.print("\nRadius: ");
                Scanner keyboard7 = new Scanner(System.in);
                int radius = keyboard7.nextInt();

                System.out.println("\nThe area is: " + area_circle(radius) + " square units");

            } else {
                System.out.println("\nGoodbye");
                break;
            }

        }

    }


    // returns the area of a circle
    public static double area_circle( int radius ){
        return Math.round((radius * radius * Math.PI)* 100.0) / 100.0;
    }


    // returns the area of a rectangle
    public static int area_rectangle( int length, int width ){
        return (length * width);
    }


    // returns the area of a square
    public static int area_square( int side ) {
        return (side * side);
    }


    // returns the area of a triangle
    public static double area_triangle( int base, int height ){
    return (0.5 * base * height);
    }
}