如何在不使用 public static void main (String[]args) 的情况下在 vs 代码中获取 Java 程序中的用户输入

Question

Can anyone please help me how to get user input in java programs in vs code without using public static void main (String [] args)

I can safely do this thing using method call in BlueJ ide but couldn't figure out how to do this in vs code or any other ides....

Here is the simple code that I want to run--

public class Rectangle
{
    public static void main (int l, int b)
    {
        int area, peri;
        area = l*b;
        peri = 2*(l+b);
        System.out.println("Area = "+area);
        System.out.println("Perimeter = "+peri);
    } 
}

Answer 1

There isn't a practical alternative if you are writing a stand-alone command line application in Java.

There are various libraries for command line argument parsing in Java, but (AFAIK) they all require you to write a public static void main (String [] args) method .... even if it is just simple boilerplate code.

(This is not true for all kinds of Java application. For example webapps in a web container, JavaFX applications, or ... applets)

Answer 2

You cant run a program with out main program. Execution always starts from main program.Your IDE may automatically generate main program, But if you are looking for an alternative way of ( other than command line argument)  getting input  you can use Scanner or any input stream methods 



 import java.util.Scanner
    public class Rectangle
    { 
        public static void main(String arg[])
        {    Scanner myObj = new Scanner(System.in);  // Create a Scanner object
            int l= myObj.nextInt();  // Read user input
            int b=myObj.nextInt(); 
            int area = l*b;
            int peri = 2*(l+b);
            System.out.println("Area = "+area);
            System.out.println("Perimeter = "+peri);
        } 
    }

Answer 3

You can't not do that.

As described here a java application entry point has to be public static void main(String[] args) .

This makes sense. The parameters from the command line arguments are Strings, not matter what. To make int out of it, there would be an implicit conversion. Where do you catch parsing errors for that if it happens before it reaches your code?