B5 Day 28 user input checker

import java.util.Scanner;

// combining 25C and 27B to make a checker
public class Main {
    public static void main(String[] args) {

        Main call25A = new Main();
        Scanner sc = new Scanner(System.in);
        String txt1 = "";
        String txt2 = "";
        double num1 = 0;
        double num2 = 0;
        String userInput;
        boolean isValid = true; // isang false lang ang kelangan

        System.out.print("Enter txt1 >> ");
        userInput = sc.nextLine();
        if (userInput == null || userInput.length() == 0) {
            isValid = false;
        } else {
            txt1 = userInput;
        }

        System.out.print("Enter txt2 >> ");
        userInput = sc.nextLine();
        if (userInput == null || userInput.length() == 0) {
            isValid = false;
        } else {
            txt2 = userInput;
        }

        System.out.print("Enter num1 >> ");
        userInput = sc.nextLine();
        if (userInput == null || userInput.length() == 0
            || call25A.isNumeric(userInput) == false) {
            isValid = false;
        } else {
            num1 = Double.parseDouble(userInput);
        }

        System.out.print("Enter num2 >> ");
        userInput = sc.nextLine();
        if (userInput == null || userInput.length() == 0
            || call25A.isNumeric(userInput) == false) {
            isValid = false;
        } else {
            num2 = Double.parseDouble(userInput);
        }

        if (isValid) {
            System.out.println("txt1: " + txt1);
            System.out.println("txt2: " + txt2);
            System.out.println("num1: " + num1);
            System.out.println("num2: " + num2);
        } else {
            System.out.println("One of the user input is invalid");
        }
    }

    public boolean isNumeric(String strNum) {
        if (strNum == null) {
            return false;
        }
        try {
            double d = Double.parseDouble(strNum);
        } catch (NumberFormatException nfe) {
            return false;
        }
        return true;
    }
}