Q:

I can't get the exact method calling for this code

I'm trying to write a simple code in Java but I keep getting error for the method calling. 
package tutorialproject2;
import java.util.Scanner;

public class Tutorialproject2 {

    static Scanner input = new Scanner(System.in);    
    public static void main(String[] args) {

    InputTest();
    Calculate(); 
    }

    public static void InputTest(){

        String message = input.nextLine();
        System.out.println(Hello(message));

    }

    public static String Hello(String message){
       if (message.equals("Hi")){
           return "Hello";
       }else{
           return "Goodbye";
       }  

    }

    public int Calculate(int a,int b){

        a = input.nextInt();
        b = input.nextInt();

        int answer = a * b;

        return answer;

    }

A:

You have the method Calculate(int a,int b) with 2 parameters but call the method without parameters Calculate().
I suppose you should change the method Calculate(int a,int b) to 
public static int Calculate(){

    int a = input.nextInt();
    int b = input.nextInt();

    int answer = a * b;

    return answer;

}

and as @Visme mentioned, to add static keyword.
or you can leave your method as
public int Calculate(){

        int a = input.nextInt();
        int b = input.nextInt();

        int answer = a * b;

        return answer;

}

In this case in the main function, you should call the method this way:
new Tutorialproject2().Calculate();

A:

should be in this way,   int var =  Calculate(3,5); , can't be calculate() alone as it has a return type and arguments.
You could call methods with return type void alone like InputTest();
as you return integer from this method and the method has parameters so you should pass the required parameters here (of integer type), 
public static int Calculate(int a,int b){
. . .
return answer;
}

