JAVA Variable declaration not allowed here

Question

I get an error "Variable declaration not allowed here" and I don't know why, I'm new in java and can't find answer :/ As it says, I can't make "int" in "if" but is there a way to create it?

import java.io.PrintWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;import java.util.Scanner;
 public class test{
  public static void main(String[] args) throws FileNotFoundException{
    File plik = new File("test.txt");
    PrintWriter saver = new PrintWriter("test.txt");

     int score = 0;
     System.out.println("Q: What's bigger");
     System.out.println("A: Dog B: Ant");
     Scanner odp = new Scanner(System.in);
     string odpo = odp.nextLine();

     if(odpo.equals("a"))
        int score = 1;
     else
         System.out.println("Wrong answer");

  }
}

Solution 1

string must be changed to String.

By writing int score you're trying to declare a new variable that already exists, which you declared before already. Just remove the int part and you will get the assignment you want.

Solution 2

As per Java spec, You cannot declare a local variable when there is no scope. While declaring int score = 1 in if, there is no scope. http://docs.oracle.com/javase/specs/jls/se7/html/jls-6.html

A local variable, one of the following
*A local variable declared in a block
*A local variable declared in a for statement

Also you have already declared a variable named score above. Even if you remove that declaration, you'll get the error because of the above reason.

Solution 3

Change int score = 1; to score = 1;.

Explanation:

To declare variable we use

someType variable;

To assign (or change) value to variable we use

variable = value;

We can mix these instruction into one line like;

someType variable = value;

So when you do

int score = 1;

you first declare variable score and then assign 1 to it.

Problem here is that we can't have two (or more) local variables with same name in same scope. So something like

int x = 1;
int x = 2;
System.out.println(x)

is incorrect because we can't decide which x we should use here.

Same about

int x = 1;
{
    int x = 2;
    System.out.println(x)
}

So if you simply want to change value of already created variable use only assignment, don't include declaration part (remove type information)

int x = 1;
//..
x = 2;//change value of x to 2

---

Now it is time for confusing part - scope. You need to understand that variable have some are in which they can be used. This area is called scope, and is marked with { } brackets which surrounds declaration of variable. So if you create variable like

{
    int x = 1;
    System.out.println(x); //we can use x here since we are in its scope 
}
System.out.println(x); //we are outside of x scope, so we can't use it here

int x = 2;
System.out.println(x); //but now we have new x variable, so it is OK to use it

So because of that scope limitation declarations in places like

if (condition)
    int variable = 2;
else
    int variable = 3;

are incorrect because such code is equal to

if (condition){
    int variable = 2;
}else{
    int variable = 3;
}

so this variable couldn't be accessible anywhere.