java - why when final variable initialize value inline that variable compatible to smaller data type without cast?

This is my Example java code.

class Example{
    public static void main(String args[]){
        int x = 65;
        final int y = 65;
        final int z;
        z = 65;
        char ch;

        ch = 'A';
        ch = 65;
        ch =(char) x; // narrow casting
        ch = y;         //line 2 
        ch = z;         //line 3 compile time error
    }
}

why when final variable y initialize value inline that variable compatible to smaller data type without casting but final variable z initialize value after declared it that occurs compiler error.

Please tell me technically why this happens.