Java OCA OCP Practice Question 1755

Question

How many constructors in Exception1 compile in the following class? 

package mypkg;/* w ww .  j a  va  2  s. co m*/
public class Exception1 extends Exception {
   public Exception1() {
      super("Wrong");
   }


   public Exception1(String message) {
      super(new Exception(new Exception1()));
   }


   public Exception1(Exception cause) {}
}
  • A. None
  • B. One
  • C. Two
  • D. Three


D.

Note

The Exception class contains multiple constructors, including one that takes Throwable, one that takes String, and a no-argument constructor.

The first Exception1 constructor compiles, using the Exception constructor that takes a String.

The second Exception1 constructor also compiles.

The two statements, super() and new Exception(), actually call the same constructor in the Exception class, one after another.

The last Exception1 compiles with the compiler inserting the default no-argument constructor super(), because it exists in the Exception class.

All of the constructors compile, and Option D is the correct answer.




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