Language Fundamentals - General Questions

What is the output of the following program?

public class Main {
    public static void main(String[] args) {
        System.out.println('a' + 'b');
    }
}

What is the default value of an int field (instance variable)?

Which keyword makes a variable's value unchangeable after assignment?

What is the output of the following program?

public class Main {
    public static void main(String[] args) {
        var list = new java.util.ArrayList<String>();
        list.add("x");
        System.out.println(list.size());
    }
}

What is the output of the following program?

public class Main {
    public static void main(String[] args) {
        char c = 'A';
        c += 2;
        System.out.println(c);
    }
}