New to Java

Hi,

Can anyone explain me why the following code gives comple time error ?

public class ScopeTest {
    private int i;
    
    public void testMethod() {
        int i=10;
        {
            int i = 12; //Compile time Error. Variable i already defined in the scope.
        }
    }
}

I am not able to understand clearly the scope rules ?

Thanks in advance,