Unreachable Blocks in java

Core java Interview Questions exception handling interview questions

Unreachable Catch Blocks:

• The block of statements to which the control would never reach under any case can be called as unreachable blocks.
• Unreachable blocks are not supported by java.
• Thus catch block mentioned with the reference of  "Exception" class should and must be always last catch block. Because Exception is super class of all exceptions.

Program:

1. package com.instanceofjava;
2. public class ExcpetionDemo {
3. public static void main(String agrs[])
4. {
5.  
6. try
7. {
8. //statements
9. }
10. catch(Exception e)
11. {
12. System.out.println(e);
13. }
14. catch(ArithmeticException e)//unreachable block.. not supported by java. leads to error
15. System.out.println(e);
16. }
17. }

\Java Example program on unreachable catch block

1. package com.instanceofjava;
2. public class ExcpetionDemo {
3. public static void main(String agrs[])
4. {
5.  
6. try {
7.            
8.  System.out.println("Excpetion handling interview questions Java unreachable block");
9.             
10. } catch (IllegalThreadStateException e) {
11.           e.printStackTrace();
12. }catch (IllegalArgumentException e) {
13.             e.printStackTrace();
14. }catch (Exception e) {
15.         e.printStackTrace();
16.  }
17.    
18. }
19. }

Output:

1. Excpetion handling interview questions Java unreachable block

1. package com.instanceofjava;
2. public class ExcpetionDemo {
3. public static void main(String agrs[])
4. {
5.  
6. try {
7.            
8.  System.out.println("Excpetion handling interview questions Java unreachable block");
9.             
10. }
11. catch (Exception e) { 
12.         e.printStackTrace();
13.  }catch (IllegalThreadStateException e) {//Error: Unreachable catch block for
14.  //IllegalThreadStateException. It is already handled by the catch block for Exception
15.           e.printStackTrace();
16. }catch (IllegalArgumentException e) {
17.             e.printStackTrace();
18. }
19.    
20. }
21. }

Bagikan

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Unreachable Blocks in java

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Oleh Kris Kimcil

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