Error Handling Techniques In Java
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Java Error Handling Design Pattern
problem that arises during the execution of a program. When an Exception occurs the normal flow of the program is disrupted and the program/Application terminates abnormally, which is not recommended, therefore, these exceptions are to be handled. An exception can occur for many different reasons. Following are some scenarios where an exception occurs. A user has entered an invalid data. A file that needs to be opened cannot be found. A network connection has been lost in the middle of communications or the JVM has run out of memory. Some of these exceptions are caused by user error, others by programmer error, and others by physical resources that have failed in some manner. Based on these, we have three categories of Exceptions. You need to understand them to know how exception handling works in Java. Checked exceptions − A checked exception is an exception that occurs at the compile time, these are also called as compile time exceptions. These exceptions cannot simply be ignored at the time of compilation, the programmer should take care of (handle) these exceptions. For example, if you use FileReader class in your program to read data from a file, if the file specified in its constructor doesn't exist, then a FileNotFoundException occurs, and the compiler prompts the pro
Java Web Services Wireless Java Print Subscribe to ONJava Subscribe to Newsletters Best Practices for Exception Handling by Gunjan Doshi 11/19/2003 One of the problems with exception handling is knowing when and how
Java Error Handling Examples
to use it. In this article, I will cover some of the best error handling techniques in sql server practices for exception handling. I will also summarize the recent debate about the use of checked exceptions. We as programmers error handling techniques in informatica want to write quality code that solves problems. Unfortunately, exceptions come as side effects of our code. No one likes side effects, so we soon find our own ways to get around them. I http://www.tutorialspoint.com/java/java_exceptions.htm have seen some smart programmers deal with exceptions the following way: public void consumeAndForgetAllExceptions(){ try { ...some code that throws exceptions } catch (Exception ex){ ex.printStacktrace(); } } What is wrong with the code above? Once an exception is thrown, normal program execution is suspended and control is transferred to the catch block. The catch block catches the exception and just suppresses it. Execution of the program continues http://www.onjava.com/pub/a/onjava/2003/11/19/exceptions.html after the catch block, as if nothing had happened. How about the following? public void someMethod() throws Exception{ } This method is a blank one; it does not have any code in it. How can a blank method throw exceptions? Java does not stop you from doing this. Recently, I came across similar code where the method was declared to throw exceptions, but there was no code that actually generated that exception. When I asked the programmer, he replied "I know, it is corrupting the API, but I am used to doing it and it works." Related Reading Java Enterprise Best Practices By The O'Reilly Java Authors It took the C++ community several years to decide on how to use exceptions. This debate has just started in the Java community. I have seen several Java programmers struggle with the use of exceptions. If not used correctly, exceptions can slow down your program, as it takes memory and CPU power to create, throw, and catch exceptions. If overused, they make the code difficult to read and frustrating for the programmers using the API. We all know frustrations lead to hacks and code smells. The client code may circumvent the issue by just
Filed Under: Exception HandlingIn this tutorial we will discuss what is an exception and how it can be handled in java programming language. What is an exception? An Exception can be anything which interrupts the normal http://beginnersbook.com/2013/04/java-exception-handling/ flow of the program. When an exception occurs program processing gets terminated and doesn't continue http://howtodoinjava.com/best-practices/java-exception-handling-best-practices/ further. In such cases we get a system generated error message. The good thing about exceptions is that they can be handled. We will cover the handling part later in this same tutorial. When an exception can occur? Exception can occur at runtime (known as runtime exceptions) as well as at compile-time (known Compile-time exceptions). Reasons for Exceptions There error handling can be several reasons for an exception. For example, following situations can cause an exception - Opening a non-existing file, Network connection problem, Operands being manipulated are out of prescribed ranges, class file missing which was supposed to be loaded and so on. Difference between error and exception Errors indicate serious problems and abnormal conditions that most applications should not try to handle. Error defines problems that are not expected to be caught under handling techniques in normal circumstances by our program. For example memory error, hardware error, JVM error etc. Exceptions are conditions within the code. A developer can handle such conditions and take necessary corrective actions. Few examples - DivideByZero exception NullPointerException ArithmeticException ArrayIndexOutOfBoundsException Advantages of Exception Handling Exception handling allows us to control the normal flow of the program by using exception handling in program. It throws an exception whenever a calling method encounters an error providing that the calling method takes care of that error. It also gives us the scope of organizing and differentiating between different error types using a separate block of codes. This is done with the help of try-catch blocks. Why to handle exception? If an exception is raised, which has not been handled by programmer then program execution can get terminated and system prints a non user friendly error message. Ex:-Take a look at the below system generated exception An exception generated by the system is given below Exception in thread "main" java.lang.ArithmeticException: / by zero at ExceptionDemo.main(ExceptionDemo.java:5) ExceptionDemo : The class name main : The method name ExceptionDemo.java : The filename java:5 : Line number For a novice user the above message won't be easy to understand. In order to let them know that what went wrong we use exception handling in java program. We ha
collectionRelated ConceptsVersion HistorySpringSpring AOPSpring CoreSpring MVCSpring SecurityFrameworksRESTEasyJerseyDropwizardHibernateMavenLog4jLog4j 2JUnitTestNGJPAMore TopicsBest PracticesRegular ExpressionsDesign PatternsPuzzlesAlgorithmsJavaScript/jQueryXMLJDBCHome > Core Java > Exception Handling > Top 20 Java Exception Handling Best PracticesTop 20 Java Exception Handling Best PracticesApril 4, 2013 by Lokesh Gupta This post is another addition in best practices series available in this blog. In this post, I am covering some well-known and some little known practices which you must consider while handling exceptions in your next java programming assignment. Follow this link to read more about exception handling in java.Table of Contents Type of exceptions User defined custom exceptions Best practices you must consider and follow Never swallow the exception in catch block Declare the specific checked exceptions that your method can throw Do not catch the Exception class rather catch specific sub classes Never catch Throwable class Always correctly wrap the exceptions in custom exceptions so that stack trace is not lost Either log the exception or throw it but never do the both Never throw any exception from finally block Always catch only those exceptions that you can actually handle Don't use printStackTrace() statement or similar methods Use finally blocks instead of catch blocks if you are not going to handle exception Remember "Throw early catch late" principle Always clean up after handling the exception Throw only relevant exception from a method Never use exceptions for flow control in your program Validate user input to catch adverse conditions very early in request processing Always include all information about an exception in single log message Pass all relevant information to exceptions to make them informative as much as possible Always terminate the thread which it is interrupted Use template methods for repeated try-catch Document all exceptions in your application in javadocBefore we dive into deep concepts of exception handling best practices, lets start with one of the most im