How can I use a user input String from one method in another?-CodePudding

This point of this program is to limit the character length of a username to 20 characters. It is one part of a larger program which currently only contains a Main method. In the interest of cleaning and clarifying my code, I would like to separate the various functions into distinct methods.

Currently, I'm trying to set class variables so that they can be used in multiple methods. This is what I have so far:


public class Program
{
    Scanner read = new Scanner(System.in);
    String firstName = read.nextLine();
    String lastName = read.nextLine();
    
    public void main(String[] args) {
        domainCharLimit();
    }
    
    public void domainCharLimit() {
        String firstNameNew = firstName.replace("'", "");
        String lastNameNew = lastName.replace("'", "");
        String domainUsername = firstNameNew   "."   lastNameNew;
        if (domainUsername.length()>20) {
                String cutName = domainUsername.substring(0, 20);
                domainUsername = cutName;
            }
        System.out.print(domainUsername);
    }    
}

I have tried setting one or both methods to static, which did not resolve the issue. In this state, when run, the program will not return an errors but rather give "no output"

CodePudding user response：

Main method has to be static! It is entry to your program and its signature has to be like that.

In order to call non static method inside it you need to instantiate an object and call it on that object. In your case something like

public static void main(String[] args) {
   Program p =  new Program();
   p.domainCharLimit();
}

CodePudding user response：

First: Main Method should be always static.

Second: Because you are calling domainChatLimit() from Main(static) than it should be also static

Third: Because you used firstName, lastName attributes in a static method domainChatLimit() then they should be also static

Fourth: Scanner should be also static because you are using it to get firstName, lastName and they are both static.

NOTE: There is no need to define a new instance of this class to call an internal method

Solution should be like below (tested successfully):

import java.util.Scanner;

public class Program{

        // variables below should be defined as static because they are used in static method
       static Scanner read = new Scanner(System.in);
       static String firstName = read.nextLine();
       static String lastName = read.nextLine();
        
       // Main method is static
        public static void main(String[] args) {
            //There is no need to define a new instance of this class to call an internal method
            domainCharLimit();
        }
        
        // calling from main static method so it should be static
        public static void domainCharLimit() {
            String firstNameNew = firstName.replace("'", "");
            String lastNameNew = lastName.replace("'", "");
            String domainUsername = firstNameNew   "."   lastNameNew;
            if (domainUsername.length()>20) {
                    String cutName = domainUsername.substring(0, 20);
                    domainUsername = cutName;
                }
            System.out.print(domainUsername);
        }   
}