Exception is a unexpected output during execution of code in programing language. Due to exception execution of program stops.In Ruby, Exceptions are basically used to handle different type of errors, which may raise during execution of program and we cant take suitable action instead of breaking the program completely.

Ruby handles exceptions easily. We write the code that raise an exception in between begin/end block and use rescue to tell the types of exceptions that we want to handle.

Syntax :

begin  
# -  
rescue Exception_Type_one  
# -  
rescue Exception_Type_two  
# -  
else  
# Other Exception_Type_three
# Default execution
end

The raised Exception against each of the params is compared by Ruby. If the match will found the exception named in the rescue clause is the same as the type of the currently thrown exception. If not found, it executes, else block.

Retry ni  exception

begin
   file = open("/notexistant_file")
   if file
      puts "File opened successfully"
   end
rescue
   file_name = "existant_file"
   retry
end

The following is the execution of the process

 When exception occurred at open file and it went to rescue. file_name was re-assigned

By retry went to the beginning of the begin,  this time file opens successfully and continued the other process.