How to call non-static method?

Question

I am writing this code to determine whether a number is even or odd, if it's even it returns true, if it's not then it returns false. the given syntax is public boolean isEven(int n) so I can't change it.

class Main { // Given
  public boolean isEven(int n)   { // Given
   if(n % 2==0){// I wrote from this
   return true;
   }else{
     return false;
   }

  }
  isEven(2); //To this

}

When I try to run this, I get these errors:

exit status 1
Main.java:14: error: invalid method declaration; return type required
  isEven(2);
  ^
Main.java:14: error: illegal start of type
  isEven(2);
         ^
2 errors

Answer 1

To invoke an instance method (one that's not static ), you need an instance on which to invoke:

class Main {
    public boolean isEven(int n) {
        return n % 2==0;
    }
    public static void main(String[] args) {
        Main obj = new Main();
        System.out.println(obj.isEven(2));
    }
}

Note also the simplification of your code to a single statement.