Loop variable cannot be resolved to variable after loop

Question

import java.io.IOException;
import java.util.Scanner;

public class Chapter_3_Self_Test {
    public static void main (String args []) throws IOException {
        Scanner sc = new Scanner (System.in);
        char a;
        for (int counter = 0; a == '.'; counter++)  {
            a = (char) System.in.read();
        }
        System.out.println(counter);

    }
}

I'm a beginner at Java. When I run this code, I get the error message that counter cannot be resolved to a variable. How do I fix this? I tried converting counter to a string, but that did nothing.

Answer 1

The variable counter only exists within the scope of the loop. In order to reference it after the loop, you'll need to define it outside of the loop:

import java.io.IOException;
import java.util.Scanner;

public class Chapter_3_Self_Test {
    public static void main (String args []) throws IOException {
        Scanner sc = new Scanner (System.in);
        int counter = 0;
        for (char a; a == '.'; counter++)   {
            a = (char) System.in.read();
        }
        System.out.println(counter);
    }
}

Note that conversely, char a can be declared within the scope of the for loop, since it is not used outside of the loop.