GUI.java

import javax.swing.*;

public class GUI {

    public static void runGui() {
        System.out.println("----------------------- Hello From GUI -----------------------");
        String strObjectMass = JOptionPane.showInputDialog(null, "Enter Object Mass");
        double objectMass = 0.0;

        try {
            objectMass = Double.parseDouble(strObjectMass);
        } catch (Exception ignored) {
        }
        double objectWeight = ObjectMeasure.calculateObjectWeight(objectMass);

        String message = "";

        if (objectWeight < 10)
            message = "Too Light";
        else if (objectWeight > 1000)
            message = "Too Heavy";

        JOptionPane.showMessageDialog(null, "Object Weight = " + objectWeight + "\n" + message);


    }
}

Main.java

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        System.out.println("What Type Of Interface Do You Wanna Use");
        System.out.println("1 - Graphical User Interface");
        System.out.println("2 - Text-Based User Interface");
        System.out.print("choice : ");
        System.out.println("");
        Scanner console = new Scanner(System.in);
        int userInterface = console.nextInt();

        if (userInterface == 1)
            GUI.runGui();
        else if (userInterface == 2)
            TUI.runTui();
        else
            System.out.println("Wrong Input!!!");


    }
}

ObjectMeasure.java

public class ObjectMeasure {

    public static double calculateObjectWeight(double objectMass) {
        return objectMass * 9.8;
    }
}

TUI.java

import java.util.Scanner;

public class TUI {

    public static void runTui() {
        System.out.println("----------------------- Hello From TUI -----------------------");
        Scanner console = new Scanner(System.in);
        System.out.print("Enter The Object Mass : ");
        double objectMass = console.nextDouble();
        double objectWeight = ObjectMeasure.calculateObjectWeight(objectMass);
        System.out.println("Object Weight = " + objectWeight);

        if (objectWeight > 1000)
            System.out.println("Too Heavy");
        else if (objectWeight < 10)
            System.out.println("Too Light");

    }
}