Exception flow control could be expensive.

As a developer sometimes we use exceptions as flow control. It could be expensive. I am going to show you how a simple change could help you to save a lot of time by simply not accepting exception as your code flow controller.
In this example, I will throw an exception if required data is not available during execution I will throw an IllegalArgumentException and in another case, I simply return a value using which call is going to take the decision based on the value then we will see how different it will be.

	package com.andy.control;
	public class FlowControlExample {
	public static void main(String[] args) {
	FlowControlExample example = new FlowControlExample();
	long startTime = System.currentTimeMillis();
	for (int i = 0; i < 100_000_000; i++) {
	try {
	String fullName = example.getFullNameThrowException(null, "middle", "");
	} catch (IllegalArgumentException e) {
	}
	}
	long timeTaken = System.currentTimeMillis() - startTime;
	System.out.println(" Time taken to complete in case of exception is thrown. " + (timeTaken / 1000) + " in secs.");
	startTime = System.currentTimeMillis();
	for (int i = 0; i < 100_000_000; i++) {
	String fullName = example.getFullNameReturnValue(null, "middle", "");
	}
	timeTaken = System.currentTimeMillis() - startTime;
	System.out.println(" Time taken to complete in case of a value returned. " + (timeTaken / 1000) + " in secs.");
	}
	private String getFullNameThrowException(String firstName, String middleName, String lastName) {
	if ((firstName == null || firstName.isEmpty()) && (lastName == null || lastName.isEmpty())) {
	throw new IllegalArgumentException(" First and / or Last name cannot be null or empty.");
	}
	return firstName + " " + middleName + " " + lastName;
	}
	private String getFullNameReturnValue(String firstName, String middleName, String lastName) {
	if ((firstName == null || firstName.isEmpty()) && (lastName == null || lastName.isEmpty())) {
	return "";
	}
	return firstName + " " + middleName + " " + lastName;
	}
	}

view raw FlowControlExample.java hosted with ❤ by GitHub

Code Output

In case of exception, it will take around a minute for execution and in another case it is insignificant. Both methods are invoked one million times to determine the impact.

Code Output

I request you to think again if you are using exception as your flow controller in a code which will be invoked many times.

Then what if I have to address an exception scenario 

If I need to address an exception scenario then for optimization I could pre-allocate the exception object so that I can use them multiple times.

	package com.andy.control;
	public class FlowControlExample {
	private static final IllegalArgumentException ILLEGAL_ARGUMENT_EXCEPTION = new IllegalArgumentException(" First and / or Last name cannot be null or empty.");
	public static void main(String[] args) {
	FlowControlExample example = new FlowControlExample();
	long startTime = System.currentTimeMillis();
	for (int i = 0; i < 100_000_000; i++) {
	try {
	String fullName = example.getFullNameThrowException(null, "middle", "");
	} catch (IllegalArgumentException e) {
	}
	}
	long timeTaken = System.currentTimeMillis() - startTime;
	System.out.println(" Time taken to complete in case of exception is thrown. " + timeTaken + " in milliSecs.");
	startTime = System.currentTimeMillis();
	for (int i = 0; i < 100_000_000; i++) {
	String fullName = example.getFullNameReturnValue(null, "middle", "");
	}
	timeTaken = System.currentTimeMillis() - startTime;
	System.out.println(" Time taken to complete in case of a value returned. " + timeTaken + " in milliSecs.");
	}
	private String getFullNameThrowException(String firstName, String middleName, String lastName) {
	if ((firstName == null || firstName.isEmpty()) && (lastName == null || lastName.isEmpty())) {
	throw ILLEGAL_ARGUMENT_EXCEPTION;
	}
	return firstName + " " + middleName + " " + lastName;
	}
	private String getFullNameReturnValue(String firstName, String middleName, String lastName) {
	if ((firstName == null || firstName.isEmpty()) && (lastName == null || lastName.isEmpty())) {
	return "";
	}
	return firstName + " " + middleName + " " + lastName;
	}
	}

view raw FlowControlExample.java hosted with ❤ by GitHub

Code Output

In this case, you can see the result is much better but still high than return statement.

Let me know your thoughts about it.