Java OCA OCP Practice Question 2399

Question

Given the following code, 

class Course { /*from  w ww .  j  a  v  a 2 s .c o  m*/
    void enroll(long duration) { 
        System.out.println("long"); 
    } 
    void enroll(int duration) { 
        System.out.println("int"); 
    } 
    void enroll(String s) { 
        System.out.println("String"); 
    } 
    void enroll(Object o) { 
        System.out.println("Object"); 
    } 
}

what is the output of the following code? 

public class Main { 
    public static void main(String args[]) { 
        Course course = new Course(); 
        char c = 10; 
        course.enroll(c); 
        course.enroll("Object"); 
    } 
} 

a  Compilation error 
b  Runtime exception 

c  int  
   String 

d  long  
   Object 



c

Note

No compilation issues exist with the code.

You can overload methods by changing the type of the method arguments in the list.

Using method arguments with data types having a base-derived class relationship (Object and String classes) is acceptable.

Using method arguments with data types for which one can be automatically converted to the other (int and long) is also acceptable.

When the code executes course.enroll(c), char can be passed to two overloaded enroll methods that accept int and long.

The char gets expanded to its nearest type-int-so course.enroll(c) calls the overloaded method that accepts int, printing int.

The code course.enroll("Object") is passed a String value.

Although String is also an Object, this method calls the specific (not general) type of the argument passed to it.

So course.enroll("Object") calls the overloaded method that accepts String, printing String.




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