implicit type casting should not works from char to String. How is this possible ?

Question

Converting from char to String should cause the following error: This code:

char [] arr = {'H', 'e', 'l', 'l', 'o'};
        String c = arr[1]; 

Error :Type mismatch: cannot convert from char to String

This code :

char [] arr = {'H', 'e', 'l', 'l', 'o'};
String c = "";
for(char i : arr) {
    c += i;
}

Works.

Answer 1

The += operator, like the + operator, will perform string conversion, when one of its operands is a String and the other isn't.

The code with += will use string conversion to convert i from a char to a String for concatenation to c, a String.

The code with = will not use string conversion, because it's not in the list of acceptable conversions for assignment contexts, according to the JLS, Section 5.2.