Try, Catch and Finally in Java

In this tutorial we will see about try, catch and finally blocks in Java. When we talk about these 3 blocks its come under Exception Handling and one on the finest feature in Java to handle both checked and UN-checked exceptions.

• try() - Try block used to hold statements which may cause exception at compile time or at run-time. Those statements will be surrounded with try block.
• catch() - Catch block used to catch if any exception occurred in try block statements. Basically list of exceptions will be specified in the catch statement as like given below examples. Before Java 7 each exception should be specified in separate catch blocks and need to catched. But in Java 7 we have got a cool feature to use multi-catch exception handling. Please refer to our earlier tutorial for Java 7 multi-catch. 
• finally() - Finally block will execute no matter whether if any exception occurred or not occurred, always finally block will be executed except 
• - if there are any infinite looping in try or catch block
• - or if System.exit statement present in try or catch block.

There are few interview questions were interviewer will be asked,

1. Try block can be without catch block?
Answer: Yes, but finally block is necessary in that case. 

2. Try and catch block can be without finally block?
Answer: Yes

3. Finally block can be without try or catch?
Answer: No, finally must be placed with try or try & catch block. 

4. Single try block can have multiple catch blocks?
Answer: Yes

5. Can we have multiple finally blocks?
Answer: No, for single try and catch there must be only 1 finally block.


Lets see few examples

EXAMPLE - 1

public class TryCatchFinallyTest {

 public static void main(String[] args) {
  int number = myFunction();
  System.out.println("NUMBER : "+number);
 }
 
 public static int myFunction(){
  try{
   return 20;
  
  }catch (NumberFormatException e) {
   System.out.println("NumberFormatException occured !!!");
   return 5;
  
  }catch (Exception e) {
   System.out.println("Exception occured !!!");
   return 30;
  
  }finally{
   return 10;
  }
 }
}

OUTPUT:

NUMBER : 10

EXAMPLE - 2

public class TryCatchFinallyTest {

 public static void main(String[] args) {
  int number = myFunction();
  System.out.println("NUMBER : "+number);
 }
 
 public static int myFunction(){
  try{
   return 50;
  }finally{
   return 100;
  }
 }
}

OUTPUT:

NUMBER : 100

EXAMPLE - 3

public class TryCatchFinallyTest {

 public static void main(String[] args) {
  String name = null;
  myFunction(name);  
 }
 
 public static void myFunction(String name){
  try{
   System.out.println("LENGTH: "+name.length());
   System.out.println("NAME: "+name);
  
  }catch (NullPointerException e) {
   System.out.println("NullPointerException occured !!!");
  
  }finally{
   System.out.println("Finally Executed...");
  }
  System.out.println("Function finished ...");
 }
}

OUTPUT:

NullPointerException occured !!!
Finally Executed...
Function finished ...