Unable to read input from static block using scanner class

Question

i want to read the data from the user in the static block and need to check some condition there but when i am trying to call nextInt() it causes some error

public class Test {
    static int B,H;
    static{
        Scanner s=new Scanner(System.in);
        B=H=0;
        B=s.nextInt();
        H=s.nextInt();
        s.close();
    }
}

Exception in thread "main" java.lang.ExceptionInInitializerError

Caused by: java.util.NoSuchElementException at java.util.Scanner.throwFor(Scanner.java:862) at java.util.Scanner.next(Scanner.java:1485) at java.util.Scanner.nextInt(Scanner.java:2117) at java.util.Scanner.nextInt(Scanner.java:2076) at Solution.initialise(Solution.java:21) at Solution.(Solution.java:15)

Also I cannot reproduce with the code given. Could you please provide a [MCVE]? — GBlodgett, Dec 22 '18 at 23:38
what is your jdk version? main method is mandatory from jdk 8 — Ryuzaki L, Dec 22 '18 at 23:39
@Deadpool you could compile the class and load it to the application, so the static init block would get invoked, right? — Andrew Tobilko, Dec 22 '18 at 23:50

score 1 · Answer 1 · answered Jul 01 '20 at 08:41

1

public class App {
    static int B, H;
    static {
        Scanner s = new Scanner(System.in);
        B = H = 0;
        B = s.nextInt();
        H = s.nextInt();
        s.close();
    }

    public static void main(String[] args) {

    }
}

answered Jul 01 '20 at 08:41

Ranvijay Singh

9
2

4

Although this code might solve the problem, a good answer should explain **what** the code does and **how** it helps – BDL Jul 01 '20 at 12:11

score 0 · Answer 2 · answered Dec 26 '18 at 10:01

From Java7, it is not possible to compile a program without main method. Before that, we can compile the program without the main method but cannot run the program. Just in case if you are trying any version before Java7, try adding System.exit(0) after s.close() (this will stop the compiler from searching for main methods).

score 0 · Answer 3 · edited Jul 01 '20 at 08:32

Try Compiling This

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Demo {
    static int B,H;
    static boolean flag=false;
    static {
        Scanner s=new Scanner(System.in);
        B=s.nextInt();
        H=s.nextInt();
        s.close();
        if (B<=0 || H<=0)
            System.out.println("java.lang.Exception: Breadth and height must be positive");
        else
            flag=true;
    }
public static void main(String[] args){
        if (flag) {
            int area = B*H;
            System.out.print(area);
        }
    }
}

Unable to read input from static block using scanner class

3 Answers3