The given code calculates the area of square, rectangle, triangle and circle. It allow the user to enter their choice. It then takes the user request and display the result accordingly.

import java.util.*;

class Area 
{
public static double square(double side){
    double area=side*side;
    return area;
}
public static double rectangle(double width,double height){
    double area=width*height;
    return area;
}
public static double triangle(double base,double height){
    double area=(base*height)/2;
    return area;
}
public static double circle(double radius){
    double area=(Math.PI)*(Math.pow(radius,2));
    return area;
}
public static void display(String str,double result){
    System.out.println("The Area of "+str+" is: "+result);
}
}

class AreaTest{
    public static void main(String[] args) 
    {
        boolean exit=false;
        String str=" ";
        Scanner input=new Scanner(System.in);
        do{
        System.out.println("1 Square");
        System.out.println("2 Rectangle");
        System.out.println("3 Triangle");
        System.out.println("4 Circle");
        System.out.println("5 Exit");

        System.out.print("Enter your choice: ");
        int choice=input.nextInt();
        switch(choice){
            case 1: 
              System.out.print("Enter side: ");
              double s=input.nextDouble();
              str="Square";
              Area.display(str,Area.square(s));
              break;

            case 2: 
              System.out.print("Enter width: ");
              double w=input.nextDouble();
              System.out.print("Enter height: ");
              double h=input.nextDouble();
              str="Rectangle";
              Area.display(str,Area.rectangle(w,h));
              break;

            case 3:
              System.out.print("Enter base: ");
              double b=input.nextDouble();
              System.out.print("Enter height: ");
              double ht=input.nextDouble();
              str="Triangle";
              Area.display(str,Area.triangle(b,ht));
              break;

            case 4:
              System.out.print("Enter radius: ");
              double r=input.nextDouble();
              str="Circle";
              Area.display(str,Area.circle(r));
              break;

            case 5:
              exit=true;
              System.exit(0);
           }
        }
            while(!exit);

    }
}