Exception Handling Keywords in Java

Exception handling is an important part of any Java program. It allows us to gracefully handle errors and unexpected situations.

Exception handling keywords

Java provides 5 exception handling keywords in Java. These are:

• try
• catch
• finally
• throw and
• throws

try

The try keyword is used to enclose a block of code that may throw an exception. If an exception is thrown inside the try block, the catch block will be executed.

try {
  // Code that may throw an exception
} catch (Exception e) {
  // Handle the exception
}

catch

The catch keyword is used to catch an exception that is thrown by the try block. The catch block must be followed by a parameter that specifies the type of exception that it can handle.

try {
  // Code that may throw an exception
} catch (ArithmeticException e) {
  // Handle the ArithmeticException exception
}

finally

The finally keyword is used to execute a block of code regardless of whether or not an exception is thrown. The finally block is often used to close resources, such as files and sockets.

try {
  // Code that may throw an exception
} catch (Exception e) {
  // Handle the exception
} finally {
  // Close resources
}

Example to show try, catch, and finally keywords used together.

public class ExceptionHandlingDemo {

  public static void main(String[] args) {
    try {

      int x = 10;
      int y = 0;
      // The following will throw an ArithmeticException exception
      System.out.println(x / y);
    } catch (ArithmeticException e) {

      System.out.println("Cannot divide by zero");
    } finally {

      System.out.println("Closing resources");
    }
  }
}

When we run this code, it will print the following output:

Cannot divide by zero
Closing resources

throw

The throw keyword is used to throw an exception. The throw keyword must be followed by an object of the Exception class or a subclass of the Exception class.

public void divideByZero() throws ArithmeticException {
  int x = 10;
  int y = 0;

  // Throw an ArithmeticException exception if y is 0
  if (y == 0) {
    throw new ArithmeticException("Cannot divide by zero");
  }
}

throws

The throws keyword is used to declare that a method may throw an exception. The throws keyword must be followed by a list of the exceptions that the method may throw.

public int divide(int x, int y) throws ArithmeticException {
  // Code that may throw an ArithmeticException exception

  return x / y;
}

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