Java try block is used to enclose the code that might throw an exception. It must be used within the method.
If an exception occurs at the particular statement of try block, the rest of the block code will not execute. So, it is recommended not to keeping the code in try block that will not throw an exception.
Java try block must be followed by either catch or finally block.
try{
//code that may throw an exception
}catch(Exception_class_Name ref){}try{
//code that may throw an exception
}finally{}Java catch block is used to handle the Exception by declaring the type of exception within the parameter. The declared exception must be the parent class exception ( i.e., Exception) or the generated exception type. However, the good approach is to declare the generated type of exception.
The catch block must be used after the try block only. You can use multiple catch block with a single try block.
Let's try to understand the problem if we don't use a try-catch block.
public class TryCatchExample1 {
public static void main(String[] args) {
int data=50/0; //may throw exception
System.out.println("rest of the code");
}
}As displayed in the above example, the rest of the code is not executed (in such case, the rest of the code statement is not printed).
There can be 100 lines of code after exception. So all the code after exception will not be executed.
Let's see the solution of the above problem by a java try-catch block.
public class TryCatchExample2 {
public static void main(String[] args) {
try
{
int data=50/0; //may throw exception
}
//handling the exception
catch(ArithmeticException e)
{
System.out.println(e);
}
System.out.println("rest of the code");
}
}Now, as displayed in the above example, the rest of the code is executed, i.e., the rest of the code statement is printed.
In this example, we also kept the code in a try block that will not throw an exception.
public class TryCatchExample3 {
public static void main(String[] args) {
try
{
int data=50/0; //may throw exception
// if exception occurs, the remaining statement will not exceute
System.out.println("rest of the code");
}
// handling the exception
catch(ArithmeticException e)
{
System.out.println(e);
}
}
}Here, we can see that if an exception occurs in the try block, the rest of the block code will not execute.
Here, we handle the exception using the parent class exception.
public class TryCatchExample4 {
public static void main(String[] args) {
try
{
int data=50/0; //may throw exception
}
// handling the exception by using Exception class
catch(Exception e)
{
System.out.println(e);
}
System.out.println("rest of the code");
}
}Let's see an example to print a custom message on exception.
public class TryCatchExample5 {
public static void main(String[] args) {
try
{
int data=50/0; //may throw exception
}
// handling the exception
catch(Exception e)
{
// displaying the custom message
System.out.println("Can't divided by zero");
}
}
}Let's see an example to resolve the exception in a catch block.
public class TryCatchExample6 {
public static void main(String[] args) {
int i=50;
int j=0;
int data;
try
{
data=i/j; //may throw exception
}
// handling the exception
catch(Exception e)
{
// resolving the exception in catch block
System.out.println(i/(j+2));
}
}
}In this example, along with try block, we also enclose exception code in a catch block.
public class TryCatchExample7 {
public static void main(String[] args) {
try
{
int data1=50/0; //may throw exception
}
// handling the exception
catch(Exception e)
{
// generating the exception in catch block
int data2=50/0; //may throw exception
}
System.out.println("rest of the code");
}
}Here, we can see that the catch block didn't contain the exception code. So, enclose exception code within a try block and use catch block only to handle the exceptions.
In this example, we handle the generated exception (Arithmetic Exception) with a different type of exception class (ArrayIndexOutOfBoundsException).
public class TryCatchExample8 {
public static void main(String[] args) {
try
{
int data=50/0; //may throw exception
}
// try to handle the ArithmeticException using ArrayIndexOutOfBoundsException
catch(ArrayIndexOutOfBoundsException e)
{
System.out.println(e);
}
System.out.println("rest of the code");
}
}Let's see an example to handle another unchecked exception.
public class TryCatchExample9 {
public static void main(String[] args) {
try
{
int arr[]= {1,3,5,7};
System.out.println(arr[10]); //may throw exception
}
// handling the array exception
catch(ArrayIndexOutOfBoundsException e)
{
System.out.println(e);
}
System.out.println("rest of the code");
}
}Let's see an example to handle checked exception.
import java.io.FileNotFoundException;
import java.io.PrintWriter;
public class TryCatchExample10 {
public static void main(String[] args) {
PrintWriter pw;
try {
pw = new PrintWriter("jtp.txt"); //may throw exception
pw.println("saved");
}
// providing the checked exception handler
catch (FileNotFoundException e) {
System.out.println(e);
}
System.out.println("File saved successfully");
}
}
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:
But if exception is handled by the application programmer, normal flow of the application is maintained i.e. rest of the code is executed.
