Java - ignore exception and continue

Question

For my Java application  I am creating an instance of a user information object and populating it with a service that I don t control the source for    The code looks like this      username given as parameter UserInfo ui   new UserInfo    try       DirectoryUser du   LDAPService findUser username       if  du  null           ui setUserInfo du getUserInfo             catch  Exception e           Whatever     If LDAPService findUser   can t locate a user  it will throw a NullPointerException and grind the rest of my application to a stop  It s okay if the user information isn t populated  so I want to be able to continue without causing everything else to start throwing exceptions   Is there a way to do this

User · Answer

You could catch the NullPointerException explicitly and ignore it - though its generally not recommended   You should not  however  ignore all exceptions as you re currently doing   UserInfo ui   new UserInfo    try       DirectoryUser du   LDAPService findUser username       if  du  null           ui setUserInfo du getUserInfo             catch  NullPointerException npe           Lulz   your NPE     Logger log  No user info for    username     will find some way to cope

User · Answer

I ve upvoted Amir Afghani s answer  which seems to be the only one as of yet that actually answers the question   But I would have written it like this instead   UserInfo ui   new UserInfo     DirectoryUser du   null  try       du   LDAPService findUser username     catch  NullPointerException npe           It s fine if findUser throws a NPE   if  du    null       ui setUserInfo du getUserInfo         Of course  it depends on whether or not you want to catch NPEs from the ui setUserInfo    and du getUserInfo   calls

User · Answer

It s generally considered a bad idea to ignore exceptions  Usually  if it s appropriate  you want to either notify the user of the issue  if they would care  or at the very least  log the exception  or print the stack trace to the console   However  if that s truly not necessary  you re the one making the decision  then no  there s no other way to ignore an exception that forces you to catch it  The only revision  in that case  that I would suggest is explicitly listing the the class of the Exceptions you re ignoring  and some comment as to why you re ignoring them  rather than simply ignoring any exception  as you ve done in your example

User · Answer

You can write a try - catch block around the line you want to have ignored   Like in the example code of yours  If you just continue your code below the closing bracket of the catch block everythings fine

User · Answer

Printing the STACK trace  logging it or send message to the user  are very bad ways to process the exceptions  Does any one can describe solutions to fix the exception in proper steps then can trying the broken instruction again

User · Answer

LDAPService should contain method like LDAPService isExists String userName  use it to prevent NPE to be thrown  If is not - this could be a workaround  but use Logging to post some warning

User · Answer

You are actually ignoring exception in your code  But I suggest you to reconsider   Here is a quote from Coding Crimes  Ignoring Exceptions     For a start  the exception should be logged at the very least   not   just written out to the console   Also  in most cases   the exception   should be thrown back to the caller for them to deal with   If it   doesn t need to be thrown back to the caller   then the exception   should be handled  And some comments would be nice too        The usual excuse for this type of code is  I didn t have time    but   there is a ripple effect when code is left in this state   Chances are   that most of this type of code will  never get out in the final   production  Code reviews or static analysis tools  should catch this   error pattern  But that s no excuse   all this does is add time to the   maintainance and debugging of the software    Even if you are ignoring it I suggest you to use specific exception names instead of superclass name  ie   Use NullPointerException instead of Exception in your catch clause

User · Answer

You are already doing it in your code   Run this example below   The catch will  handle  the exception  and you can move forward  assuming whatever you caught and handled did not break code down the road which you did not anticipate        try        throw new Exception      catch  Exception ex      ex printStackTrace        System out println  Made it       However  you should always handle an exception properly   You can get yourself into some pretty messy situations and write difficult to maintain code by  ignoring  exceptions   You should only do this if you are actually handling whatever went wrong with the exception to the point that it really does not affect the rest of the program

[java] Java - ignore exception and continue

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