Question

public class b {
    public static void main(String[] args) {
        byte b = 1;
        long l = 127;
    //  b = b + l;            // 1 if I try this then it does not compile
        b += l;               // 2 if I try this then it does     compile
        System.out.println(b);  
    }
}

I am using this code but I have problem:
I don’t understand why b=b+l; is not compiling but if I write b+=l; then it compiles and runs.

Please explain why this happens.

Answer 1

This is what the advantage of compound assignment operators like +=, -= ,etc over assignment operators, where you have to explicitly cast to the type of the right hand side but if you use compound assignment operator it implicitly does it for you.
As it is happening in your case.