Return statement in catch block !

Hello Java Gurus,
The code is not compiling when i remove return from the catch block
i dont really understand the essence of return statement in catch block
any help is greatly appreciated !
Thanks in advance !
import java.io.*;
public class fileinputstream {
   public static void main(String arg[]) {
        FileInputStream fin ;
        FileOutputStream fout;
       try {
             fin =new     FileInputStream("input_file.txt");
             int bytes_av = fin.available();
             System.out.println("bytes available the input file "+bytes_av);
       catch(FileNotFoundException e)
           System.out.println("The input file is not present");
           return;
       catch(IOException e)
           System.out.println("error while giving bytes available the input file");
           return;
       try
                 fout =new FileOutputStream("output_file.txt");
       catch(FileNotFoundException e)
           System.out.println("The output file cannot be created");
           return;
       int data=0;
       try {
           data =(int)fin.read();
       catch(IOException e) {
           System.out.println("Exception while reading from file");
        while(-1!=data)      {
                   try
                   fout.write(data);
                   catch(IOException e)
                       System.out.println("Error while writing to file");
                   try
                       data =(int)fin.read();
                   catch(IOException e)
                       System.out.println("Exception while reading from file");
        try {
               fin.close();
               fout.close();
        catch(IOException e) {
           System.out.println("Error while closing files");
}

You do understand what "return" means, don't you? It
exits the method, main() in this case.
So the return statements in the catch blocks end the
program. If you remove the return statements, the
program will continue with the code after the catch
blocks. It needs the variables "fout" and "fin"
there, and these must be initialised.
If there are no return statements in the catch
blocks, the variables "fin" and "fout" will be not
initialized when you get to the code that uses them,
and that's an error. The java compiler is telling you
that you must always initialise the variables (you
can set them to "null", for example).Great explanation !!!
Thanks !

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If statements in catch blocks

Can you use if statements in catch blocks?
(See below) Any help would be appreciated..
catch (Exception e)
// System.out.println("input error");
if (deposit < 0)
System.out.println("input error");
System.out.println( "Balance is "+ patricksChecking.getBalance());

Not only is there no good to catching an exception that's never thrown, as the previous-previous poster pointed out, you won't even be able to compile.
For those who are not using the finally bloc in exception handling, it can be indispensible.

Return statement inside try block

what is wrong if i write code like as below...please explain me since i am new to java
class sample{
public String method(){
try{
String str="abc";
return abc;
catch(Exception e){}
}

veldhanas wrote:
return abc;In your code there is no varible declared as abc. It is a value assigned in str.
Suppose if the code in try statement throws exception the return statement is skipped and the
associated catch block will get executed. So your catch block must return a result of type String.... or throw another (or the same) exception.
In this case, since there's no way the code in the given "try" block can throw an exception, it would have been better to not even have a try/catch block in the first place.
And almost never just swallow exceptions like that (an empty catch block). There are only a few cases where it's ok to swallow them (such as in finally blocks where you're cleaning up resources which may throw exceptions while cleaning up, and you want to continue cleaning up and ignore those kinds of exceptions).

Return statement in exception and consequences

Hi,
Can any one give me the explanation for my doubt?
Case 1:
I am having some code throwing some exception lets say arithematic exception in my try block.
I caught it in the catch block and at last I am having one finally?
as per normal order try block next catch block and at last finally will execute.
I execute the above code by putting a return statement inside catch block.I got the same order of execution irrespective of return statement inside catch?
What is the significance of return inside catch?
Case 2:
Lets take the scenario.
class MyException
     public static void main(String[] args)
          int i=1,j=0;
          try
               try
               System.out.println("the value is: "+(i/j));
               System.out.println("Inside try block");
               catch(ArithmeticException e)
               System.out.println("hi in ame");
               //return;
          finally
          System.out.println("inner finally");
                                        System.out.println("outer try");
          catch(Exception e)
                         e.printStackTrace();
               System.out.println("in exception");
          finally
               System.out.println("plz wait");
If return statement is there inside the inner try and catch the code out of inside outer try not getting executed Why So?
Any clarifications?
Thanking you,
Murthy.

First, please format your code as per http://forum.java.sun.com/features.jsp#Formatting
I'm not sure what part you don't understand.
.    public static void main(String[] args) {
.        try {
.            try {
.                throw new ArithmeticException();
.                System.out.println("Inside try block"); // #1
.            catch(ArithmeticException e) {
.                System.out.println("hi in ame"); // #2
.                return;
.            finally {
.                System.out.println("inner finally"); // #3
.            System.out.println("outer try"); // #4
.        catch(Exception e) {
.            System.out.println("in exception"); // #5
.        finally {
.            System.out.println("plz wait"); // #6
.    }#1 -- You won't get here because you throw AME.
#2 -- You will get here because you caught the AME you just threw.
#3 -- You will get here because it's a finally
#4 -- You won't get here. I think that this is what you're asking about: Why don't we get here? Because we've already done 'return' and this line is NOT inside a finally. The only things that can get executed after a return are finally blocks.
#5 -- You won't get here because you already caught the AME and didn't rethrow it or any other exception.
#6 -- You will get here because it's a finally.
Once you do a return, the only code you can execute before exiting the method are finally blocks. First the one corresponding to the try/cathc block where your return is, then the finally for the try/catch that encloses that one, and so on outward. The code between one finally and the next (#4 here) is NOT executed.
If you still have a question, please try to clarify exactly what behavior you don't understand.
Don't return from inside t/c/f.

Doubts reg try block and return statements

hi
public int test()
          try
               System.out.println("hi");
               return 1;
          catch(Exception e)
          System.out.println("err");
          return 2;
          finally
               System.out.println("final");
               return 3;
          //System.out.println("after");
          //return 4;
when i call this function, it will printing 3... why ??
and also compilation error is coming when i put return statement after final block.. why is it so??

but if commented the return statements in catcch and finally then it iam not getting any compilation error.
public int test()
          try
               System.out.println("hi");
               return 1;
          catch(Exception e)
          System.out.println("err");
          // return 2;
          finally
               System.out.println("final");
          //     return 3;
          System.out.println("after");
          return 4;
and iam just learning ..... regarding return and try block

Unreachable statement error occured while using return statement.

Consider this code
class q25{
     public static void main(String args[]){
          amethod(args);
     public static void amethod(String args[]){
          String str;
          try{
               str = "Hello "+args[0];
               System.out.println(str);
               System.out.println("Returning to caller");
               System.exit(0);
          catch(Exception e){
               System.out.println("Exception ocured");
               System.exit(0);
          finally{
               System.out.println("In finally");
          System.out.println("At the end of method");
}Above code compiles and runs successfully without any errors.
Now consider below code which is same as above one except "System.exit(0)" statements were replace by "return" statements. Below code when compiled gives error as
"q25.java:22: unreachable statement
System.out.println("At the end of method");
^
1 error"
One thing i didn't understood in this context that, the above code when compiled should get same error as stated above. But not. It is obvious that presence of System.exit(0) must generate unreachable statement same as when it is replaced by "return" statement. What is the difference in getting the error for above but not for below code. Pls anyone help.
class q25{
     public static void main(String args[]){
          amethod(args);
     public static void amethod(String args[]){
          String str;
          try{
               str = "Hello "+args[0];
               System.out.println(str);
               System.out.println("Returning to caller");
               return;
          catch(Exception e){
               System.out.println("Exception ocured");
               return;
          finally{
               System.out.println("In finally");
          System.out.println("At the end of method");
}

warnerja wrote:
masijade. wrote:
Since you have a "return" in both the try and the catch portions of the try/catch block *(the second of which you should never do)* , anything thing that comes after the try/catch/finally blocks will be unreachable.That is not true. There are plenty of reasons to return from a catch block. If you handle the exception instead of rethrowing it or another exception, then you'll need a return somehow, either there or after the catch block. What you should never do is "return" in a finally block, because that will mask any exception in flight about to be thrown to the caller.Perhaps masijade's use of never is too strong, but I too prefer/tend to avoid using return anywhere in try/catch/finally to avoid potential gotchas. Consider:
public class TryCatchFinally
public Data process(String s)
    Data returnData = new Data();
    try
      returnData.value = Integer.parseInt(s);
      returnData.message = "Success";
      return returnData;
    catch (Exception ex)
      returnData.value = -1;
      returnData.message = "Fail";
      return returnData;
    finally
      returnData.value = 42;
      returnData.message = "?";
public static void main(String[] args)
    TryCatchFinally demo = new TryCatchFinally();
    Data d = demo.process("2");
    System.out.println(d.message + ": " + d.value);
    d = demo.process("2.1");
    System.out.println(d.message + ": " + d.value);
class Data
    int value = 0;
    String message = "";
}

Return statement inside a catch block???

If you put a return statement inside of a catch block, what statements will be executed next? I.e., what happens to the flow of control?

If you put a return statement inside of a catchblock, what statements will be executed next? I.e.,
what
happens to the flow of control?If you write a short testing sample, compile it and
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Eek! That actually involves effort! Are you kidding?Kidding ? Me ?
I'd better waste my time writing programs for lazy OPs !
;)

Return statement at the end of try or after catch blocks

Hi
Can anyone tell me which is the better practice - to put the return statement at the end of try block or after all the catch blocks ie at the end of method.
Eg
Method A()
String str;
try{
str= [some code]
return str
catch(Exception e)
System.out.println("Exception");
} // end of method
OR
Method B()
String str;
try{
str= [some code]
}catch(Exception e)
System.out.println("Exception");
return str
} // end of method

I always try to work with only one exit point for each method.
For readability I always put the return statement as close to the end of the method as possible.
In this particular question,
I think you should put the return at the end of the method (for readability, since this is what you are
familiar with), but when I have a try-catch clause, I usually have an unrecoverable error and
should throw this further down the tree, so it usually becomes
try{
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}catch(...){
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}I think you should NEVER reflect the occurence of an error in the return-value of the
method when an unrecoverable exception occurs. Just rethrow this exception or throw another method.
Other methods look like
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This is possible in two versions:
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Object result = new ...
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else if(..)
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return result;With every time a return
if(...)
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else if(...)
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but I find the second version (which I hated when I began programming)
to be somewhat more of a (self-made) standard nowadays.
But I do not think this particular case makes much of a difference.
kind regards,

Return statement in a try catch block

Hi friends
Take a look in the code bellow
try
return (true)
finally
System.out.println("blabla");
If nothing strange hapens in the try code, the return statement will be achieved. In this case, what will hapen ? The code in the finally block will be executed ??
thanks

If nothing strange hapens in the try code, the return
statement will be achieved. In this case, what will
hapen ? The code in the finally block will be executed
??Yes. Hence the word "finally".

Return in finally block hides exception in catch block

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Christian Treber
[email protected]
public class ExceptionDemo extends TestCase
public void testException()
String lResult = "[not set]";
try
lResult = troubleMaker();
System.out.println("No exception from troubleMaker()");
} catch(Exception e)
System.out.println("Caught an exception from troubleMaker(): " + e);
System.out.println("Result: " + lResult);
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boolean lErrorP = false;
try
if(6 > 5)
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lErrorP = true;
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-- quote
If execution of the try block completes abruptly because of a throw of a value V, then there is a choice:
* If the run-time type of V is assignable to the parameter of any catch clause of the try statement, then the first (leftmost) such catch clause is selected. The value V is assigned to the parameter of the selected catch clause, and the Block of that catch clause is executed. Then there is a choice:
o If the catch block completes normally, then the finally block is executed. Then there is a choice:
+ If the finally block completes abruptly for any reason, then the try statement completes abruptly for the same reason.
-- end quote
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When a method returns a value, you must make sure that even if an exception is thrown and caught a value will be returned (or just throw the exception out of the method).
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ResultSet rs = s.executeQuery(query);
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I am trying to implement the Try/Catch for error handling, but I have
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RAISERROR with Try/Catch does not exit after exception in catch block

I am trying to propogate an error from within my proc out to the caller.
In the attached example I have 2 sets of try catch blocks.
I raiserror in the first
catch the error and then raiserror again. (I expect to exit)
I do not expect :
to get to print 'post test'
to get to second try block.
but this does not exit, instead the code flows as per 2 runs.
I do not understand the reason for the flows, as it seems counterintuitive to be raising an error but then still print following exceptions. I cannot seem to find any references that explains this behaviour.
running tests together results
print '-------------------------------------------------------'
print 'test 15'
exec test_raiseerror 15
print '-------------------------------------------------------'
print 'test 16'
exec test_raiseerror 16
print '-------------------------------------------------------'
print 'test 17'
exec test_raiseerror 17
print '-------------------------------------------------------'
print 'test 18'
exec test_raiseerror 18
print '-------------------------------------------------------'
'RESULTS'
test 15
error number provided: 15
Msg 50000, Level 15, State 1, Procedure test_raiseerror, Line 21
name hello 15
post test
15
Msg 50000, Level 15, State 1, Procedure test_raiseerror, Line 37
name hello 2 15
post test2
test 16
error number provided: 16
Msg 50000, Level 16, State 1, Procedure test_raiseerror, Line 21
name hello 16
post test
16
Msg 50000, Level 16, State 1, Procedure test_raiseerror, Line 37
name hello 2 16
post test2
test 17
error number provided: 17
post test
17
post test2
test 18
error number provided: 18
post test
18
post test2
Msg 50000, Level 17, State 1, Procedure test_raiseerror, Line 21
name hello 17
Msg 50000, Level 17, State 1, Procedure test_raiseerror, Line 37
name hello 2 17
Msg 50000, Level 18, State 1, Procedure test_raiseerror, Line 21
name hello 18
Msg 50000, Level 18, State 1, Procedure test_raiseerror, Line 37
name hello 2 18
run tests seperately
exec test_raiseerror 15
error number provided: 15
RESULTS 15
Msg 50000, Level 15, State 1, Procedure test_raiseerror, Line 21
name hello 15
post test
15
Msg 50000, Level 15, State 1, Procedure test_raiseerror, Line 37
name hello 2 15
post test2
exec test_raiseerror 16
RESULTS 16
error number provided: 16
Msg 50000, Level 16, State 1, Procedure test_raiseerror, Line 21
name hello 16
post test
16
Msg 50000, Level 16, State 1, Procedure test_raiseerror, Line 37
name hello 2 16
post test2
exec test_raiseerror 17
RESULTS 17
error number provided: 17
post test
17
post test2
Msg 50000, Level 17, State 1, Procedure test_raiseerror, Line 21
name hello 17
Msg 50000, Level 17, State 1, Procedure test_raiseerror, Line 37
name hello 2 17
exec test_raiseerror 18
RESULTS 18
error number provided: 18
post test
18
post test2
Msg 50000, Level 18, State 1, Procedure test_raiseerror, Line 21
name hello 18
Msg 50000, Level 18, State 1, Procedure test_raiseerror, Line 37
name hello 2 18
CODEBLOCK:
if object_id('test_raiseerror','P') is not null
drop proc test_raiseerror
go
create proc test_raiseerror(@id as int) as
begin
begin try
declare @name varchar(20)
select @name = 'hello'
raiserror('name %s %d',@id,1,@name,@id)
print 'next'
end try
begin catch
declare @errormessage nvarchar(4000)
declare @errornum int
select @errormessage = error_message()
, @errornum = error_severity()
print 'error number provided: ' + convert(varchar(2),@errornum)
raiserror(@errormessage, @errornum,1)
print 'post test'
end catch
begin try
select @name = 'hello 2'
raiserror('name %s %d', @id,1,@name, @id)
end try
begin catch
select @errormessage = error_message()
, @errornum = error_severity()
print @errornum
raiserror(@errormessage, @errornum,1)
print 'post test2'
end catch
end
go
sqlserver 2008 & 2008 R2

There is a Connect that describes a similiar complaint. But basically a raiserror inside a catch block does not terminate the procedure, it will continue with any additional code in the CATCH and FINALLY unless it hits a return statement.
http://connect.microsoft.com/SQLServer/feedback/details/275308/have-raiserror-work-with-xact-abort

Missing return statement error

public class Member
         public int Member(String memberid, String memberpw)
     String cs = "jdbc:oracle:thin:@255.255.255.255:1000:a123stud";
         String user = "123456";
         String pass = "123456";
          String member = "member_id";
         try
               Class.forName("oracle.jdbc.driver.OracleDriver");
               //Connection conn = DriverManager.getConnection("jdbc:odbc:myOracle");
               Connection conn = DriverManager.getConnection(cs,user,pass);
               Statement stmt = conn.createStatement();
               String query = "SELECT * FROM members";
               ResultSet rs = stmt.executeQuery(query);
             // ResultSet rs = stmt.executeQuery("SELECT * FROM members WHERE member_id = 'M0001'");
                    int counter = 0;
                    while(rs.next())
                         member = rs.getString("member_id");
                         counter++;
                         if (counter == 0)
                         return 0;
                         else
                         return 1;
                    //System.out.println("\nOracle10g at 255.255.255.255 is working!");
          catch(SQLException e)
               System.out.println("\n\nException Occured " +
                         "(Incorrect IP address, Server may be down, or SQL Exception)");
               e.printStackTrace();
          catch(ClassNotFoundException e)
               System.out.println("\n\nException Occured (CLASSNOTFOUND Exception)");
}It says i am missing the return statement,but i do have set return something,whats the error? thx for helping

For example, what happens if the SQL query doesn't
return any rows, and rs.next() is never true?The while() loop will be skipped and the if statement
will execute, which has two branches, one of which is
guaranteed to return?Oops. My bad.
I thought the ifs were inside the while.
Okay, the problem here is with the exception handling. Catching and logging and doing nothing else is usually almost as bad as just smothering them. In this case it's especially true because the method then just continues after the catch blocks, in which case there's no return.
You have to actually handle the exceptions if you're not going to propagate them. In this case, that would mean returning some reasonable default value. I'd say that's not a good idea here, and you're better off to just let the exceptions be thrown, or wrap and rethrow in your own exception.

Return statement in catch block !

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