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try/catch

 
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Hi!help how the output is 4 and 5
public class jump{
public static void main(String[] args){
for(int i=0;i<10;++i){
try{
try{
if(i%3==0)
throw new Exception("e0");
System.out.println(i);
}
catch(Exception inner){
i*=2;
if(i%3==0)throw new Exception("e1");
}
finally{
++i;
}
}
catch(Exception outer){
i+=3;
}
finally{
--i;
}
}
}
}
o/p is 4
5
please explain how is the o/p 4 and 5?

 
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Whoa, this is one complicated loop! I made a few modifications to your code and it now looks like this:
public class jump{//1
public static void main(String[] args){//2
for(int i=0;i<10;i++){//3
try{//4
try{
if(i%3==0)
throw new Exception("e0");
System.out.println(i);
}//*4
catch(Exception inner){//5
i*=2;
System.out.println("1i="+i);
if(i%3==0)throw new Exception("e1");
}//*5
finally{//6
++i;
System.out.println("2i="+i);
}//*6
}//*4
catch(Exception outer){//7
i+=3;
System.out.println("3i="+i);
}//*7
finally{//8
--i;
System.out.println("4i="+i);
}//*8
}//*3
}//*2
}//*1
Try run it and figure out yourself.
 
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Hi Nachiket,
Lets step through the code and see what is going on.
1. Start of for loop
i = 0
2. Inside 1st try block
3. Inside 2nd try block
4. 0 % 3 == 0 so throw new Exception( "e0" )
5. Catch the exception "e0" in the catch block of 2nd try block
set i = 0 * 0 = 0
i % 3 == 0 so throw new Exception( "e1" )
6. Before we leave 2nd try block execute finally block.
Set i = 0 + 1 = 1
7. Catch exception "e1" in catch statement of 1st try block
Set i = 1 + 3 = 4
8. Run finally block of 1st try block.
Set i = 4 - 1 = 3
9. Back at for loop top.
Pass loop quit condition
Increment i: i = 3 + 1 = 4
10. Inside 1st try block
11. Inside 2nd try block
12. 4 % 3 != 0 so print out 4
13. Before we end 2nd try block execute finally block
Set i = 4 + 1 = 5
14. Run finally block of 1st try block
Set i = 5 - 1 = 4
15. Back at for loop top
Pass loop condition
Increment i = 4 + 1 = 5
16. Inside 1st try block
17. Inside 2nd try block
18. 5 % 3 != 0 so print out 5
19. Before we end 2nd try block execute finally block
Set i = 5 + 1 = 6
20. Run finally block of 1st try block
Set i = 6 - 1 = 5
21. Back at for loop top
Pass loop condition
Increment i: i = 5 + 1 = 6
22. Inside 1st try block
23. Inside 2nd try block
24. 6 % 3 == 0 so throw new Exception( "e0" )
25. Catch exception "e0" inside 2nd try/catch block
Set i = 6 * 2 = 12
12 % 3 == 0 so throw new Exception( "e1" )
26. Before we quit execute the 2nd finally block
Increment i. i = 12 + 1 = 13
27. Catch exception "e1" inside 1st try/catch block
Set i = 13 + 3 = 16
28. Execute 1st finally block
Increment i. i = 16 + 1 = 17
29. Back at for loop start
Don't pass loop condition
30. Done!
Whew!
Manfred.
 
nachiket deshpande
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Thanks a lot Manfred!!
 
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