Core JAVA

try & catch block and Handling Exceptions

A method catches an exception using a combination of the try and catch keywords. A try/catch block is placed around the code that might generate an exception. Code within a try/catch block is referred to as protected code, and the syntax for using try/catch looks like the following:
try
{
   //Protected code
}catch(ExceptionName e1)
{
   //Catch block
}


Exception Handling in Java

It is a powerful feature provided in Java. It is a mechanism to handle run-time errors, so that the normal flow of the program is maintained.

Exception handling consists of the following five keywords:

  1. Try
  2. Catch
  3. Finally
  4. Throw
  5. Throws

try block
Enclose the code that might throw an exception in try block. It must be used within the method and must be followed by either catch or finally block.
Syntax of try with catch block

try{
...
}catch(Exception_class_Name reference){}


Syntax of try with finally block

try{
...
}finally{}

catch block
Catch block is used to handle the Exception. It must be used after the try block.

Code without exception handling:

class App{
  public static void main(String args[]){
      int index = 10/0;
  
      System.out.println("another code here");
    }
 }

As displayed in the above example, rest of the code is not executed i.e. another code here statement is not printed. Let’s see what happens behind the scene:

The JVM firstly checks whether the exception is handled or not. If exception is not handled, JVM provides a default exception handler that performs the following tasks:

  • Prints out exception description.
  • Prints the stack trace (Hierarchy of methods where the exception occurred).
  • Causes the program to terminate.

But if exception is handled by the application programmer, normal flow of the application is maintained i.e. rest of the code is executed. 
Code with exception handling:

class App{
  public static void main(String args[]){
      try{
          int index = 10/0;
      }catch(ArithmeticException e){
            System.out.println(e);
      }
      System.out.println("another code here");
    }
 }

Now, as displayed in the above example, rest of the code is executed i.e. another code here. statement is printed.

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Dinesh Rajput

Dinesh Rajput is the chief editor of a website Dineshonjava, a technical blog dedicated to the Spring and Java technologies. It has a series of articles related to Java technologies. Dinesh has been a Spring enthusiast since 2008 and is a Pivotal Certified Spring Professional, an author of a book Spring 5 Design Pattern, and a blogger. He has more than 10 years of experience with different aspects of Spring and Java design and development. His core expertise lies in the latest version of Spring Framework, Spring Boot, Spring Security, creating REST APIs, Microservice Architecture, Reactive Pattern, Spring AOP, Design Patterns, Struts, Hibernate, Web Services, Spring Batch, Cassandra, MongoDB, and Web Application Design and Architecture. He is currently working as a technology manager at a leading product and web development company. He worked as a developer and tech lead at the Bennett, Coleman & Co. Ltd and was the first developer in his previous company, Paytm. Dinesh is passionate about the latest Java technologies and loves to write technical blogs related to it. He is a very active member of the Java and Spring community on different forums. When it comes to the Spring Framework and Java, Dinesh tops the list!

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