Exceptions question

[Arad Chear]

4. Which are most typically thrown by an API developer or an application developer
as opposed to being thrown by the JVM? (Choose all that apply.)


A). ClassCastException
B). IllegalStateException
C). NumberFormatException
D). IllegalArgumentException
E). ExceptionInInitializerError


i think its A , C ,D

but the answer is B,C,D

why A is wrong and the developer can test the instance throw instanceof operator and if its fails thrown ClassCastException ?

[M Easter]

A developer may be able to throw a ClassCastException but it is not typical (as specified by the question).

re: instanceof. If I have a method that takes an object, and I use instanceof, then I would not throw a ClassCastException. I would throw an IllegalArgumentException because that tells the client more information: that they are breaking the contract of the method.

[Chandra Bhatt]

Hi Eisa,

You can look at various scenarios where chosen exceptions may be thrown and
handled programatically.

Try it out:

package exceptions;
 
import java.util.*;
 
public class Pilot {
 
public static void main(String... args) {
/* NumberFormatException IS-A(n) IllegalArgumentException
                 IS-A RuntimeException IS-A Exception IS-A Throwable IS-A
                 Object (of-course)  
                */
try{
Integer i1 = new Integer("3rt");
}catch(NumberFormatException nfe) {
System.err.println(nfe.getClass());
System.err.println(nfe.getMessage());
}

 
int [] a1 ={43,6,41,7,2};
try{
Arrays.sort(a1, 3, 2);
}catch(IllegalArgumentException iae) {
System.err.println(iae.getClass());
System.err.println(iae.getMessage());
}

Thread t1= new Thread() {
public void run() {
System.out.println("Running...");
}
};

               /* IllegalThreadException IS-A(n) IllegalArgumentException                     
                 IS-A RunTimeException and so on */
try{
t1.start(); 
t1.start();
}catch(IllegalThreadStateException itse) {
System.out.println(itse.getClass());
}

               /* IllegalStateException IS-A RuntimeException and so on*/
Scanner scan = new Scanner("1423 scjp 3353.3 java");

try {
System.out.println(scan.nextInt());
scan.close();
scan.nextInt();
}catch(IllegalStateException ise) {
System.out.println(ise.getClass());
System.out.println(ise.getMessage());
}

}
}

ClassCastException I may not require to tell you.

Regards,
cmbhatt
[ April 22, 2007: Message edited by: Chandra Bhatt ]

[megha joshi]

You can also stick a bookmark on pg. 370 of K&B book

[Arad Chear]

Thanks all ,

Chandra thanks for your code