Assertion in Java

Assertion facility is added in J2SE 1.4. In order to support this facility J2SE 1.4 added the keyword assert to the language, and AssertionError class. An assertion checks a boolean-typed expression that must be true during program runtime execution. The assertion facility can be enabled or disable at runtime.

Declaring Assertion

Assertion statements have two forms as given below

assert expression;

assert expression1 : expression2;

The first form is simple form of assertion, while second form takes another expression. In both of the form boolean expression represents condition that must be evaluate to true runtime.

If the condition evaluates to false and assertions are enabled, AssertionError will be thrown at runtime.

Some examples that use simple assertion form are as follows.

assert value > 5 ;

assert accontBalance > 0;

assert isStatusEnabled();

The expression that has to be asserted runtime must be boolean value. In third example isStatusEnabled() must return boolean value. If condition evaluates to true, execution continues normally, otherwise the AssertionError is thrown.

Following program uses simple form of assertion

//AssertionDemo.java

Class AssertionDemo{

Public static void main(String args[]){

System.out.println( withdrawMoney(1000,500) );

System.out.println( withdrawMoney(1000,2000) );

}

public double withdrawMoney(double balance , double amount){

assert balance >= amount;

return balance ? amount;

}

}

In above given example, main method calls withdrawMoney method with balance and amount as arguments. The withdrawMoney method has a assert statement that checks whether the balance is grater than or equal to amount to be withdrawn. In first call the method will execute without any exception, but in second call it AssertionError is thrown if the assertion is enabled at runtime.

Enable/Disable Assertions

By default assertion are not enabled, but compiler complains if assert is used as an identifier or label. The following command will compile AssertionDemo with assertion enabled.

javac ?source 1.4 AssertionDemo.java

The resulting AssertionDemo class file will contain assertion code.

By default assertion are disabled in Java runtime environment. The argument ?eanbleassertion or ?ea will enables assertion, while ?disableassertion or ?da will disable assertions at runtime.

The following command will run AssertionDemo with assertion enabled.

Java ?ea AssertionDemo

or

Java ?enableassertion AssertionDemo

Second form of Assertion

The second form of assertion takes another expression as an argument.

The syntax is,

assert expression1 : expression2;

where expression1 is the condition and must evaluate to true at runtime.

This statement is equivalent to

assert expression1 : throw new AssertionError(expression2);

Note: AssertionError is unchecked exception, because it is inherited from Error class.

Here, expression2 must evaluate to some value.

By default AssertionError doesn't provide useful message so this form can be helpful to display some informative message to the user.

Rahim Vindhani
Application Develper [Application Development & Webservices]
IBM Global Services, pune, India
email: rahim.vindhani@gmail.com
web: http://www.rahim.co.nr

express cleaning service Arlington Heights ..
In The News:

Researchers from Osaka Metropolitan University designed a 21-foot dome that combines aquaculture and hydroponics to create a self-sustaining urban food system.
The Fox News AI Newsletter gives readers the latest AI technology advancements, covering the challenges and opportunities AI presents.
ChatGPT data breach exposes personal info of users through partner Mixpanel. OpenAI confirms names, emails compromised in security incident.
Android rolls out Emergency Live Video for 911 calls, letting dispatchers see real-time scenes during emergencies. Great for holiday travel safety.
Malicious Chrome and Edge extensions collected browsing history, keystrokes and personal data from millions of users before Google and Microsoft removed them.
Google's new Call Reason feature lets Android users mark calls as urgent before dialing, displaying an urgent label to recipients using Phone by Google app.
Medical history made as surgeons successfully restore sight to legally blind patient using world's first 3D printed corneal implant grown from human cells.
Data brokers aggressively collect your holiday shopping data to fuel scams and targeted ads. Learn how to delete your digital profile before 2025 starts.
Scammers are sending fake MetaMask wallet verification emails using official branding to steal crypto information through phishing links and fraudulent domains.
Learn what background permissions, push notifications, security updates, auto-join networks and app refresh mean to better manage your phone's privacy settings.
Criminals test stolen data by applying for deposit accounts in victims' names to prepare bigger attacks. Learn why banks won't share fraud details.
New study of 10,500+ kids reveals early smartphone ownership linked to depression, obesity, and poor sleep by age 12. Earlier phones mean higher risks.
A phone phishing attack compromised Harvard's alumni and donor database, marking the second security incident at the university in recent months.
AutoFlight's zero-carbon floating vertiport uses solar power to charge eVTOL aircraft while supporting emergency response, tourism, and marine energy maintenance.
A new phone return scam targets recent buyers with fake carrier calls. Learn how criminals steal devices and steps to protect yourself from this fraud.
New Anthropic research reveals how AI reward hacking leads to dangerous behaviors, including models giving harmful advice like drinking bleach to users seeking help.
The Fox News AI Newsletter gives readers the latest AI technology advancements, covering the challenges and opportunities AI presents.
Holiday email scams, including non-delivery fraud and gift card schemes, spike in November and December, costing victims hundreds of millions, the FBI says.
Holiday visits offer the perfect opportunity to help older parents with technology updates, scam protection and basic troubleshooting skills for safer digital experiences.
Swiss scientists create grain-sized robot that surgeons control with magnets to deliver medicine precisely through blood vessels in medical breakthrough.
Researchers exploited WhatsApp's API vulnerability to scrape 3.5 billion phone numbers. Learn how this massive data breach happened and protect yourself.
Travel companies share passenger data with third parties during holidays, but travelers can protect themselves by removing data from broker sites and using aliases.
Xpeng's humanoid robot moves so realistically that crowds believed it was fake, marking a major advancement in robotics technology ahead of 2026 commercial launch.
Researchers discover phishing scam using invisible characters to evade email security, with protection tips including password managers and two-factor authentication.
iPhone and Android users can reduce battery drain and data usage by restricting Background App Refresh to Wi-Fi connections instead of mobile networks.

Implementing Microsoft CRM: setup and configuration ? notes for IT specialist

Microsoft Business Solutions CRM is web-based CRM application, deploying all... Read More

5 Time-Saving Tips in Microsoft Word

Whether you have used Microsoft Word for years, have just... Read More

Free Preventive Maintenance Software

While several preventive maintenance software manufacturers offer free trials for... Read More

5 Mac Security Tips You Can?t Live Without

So, you've bought a new Macintosh, and now you may... Read More

Software Companies: Generate New Revenue Streams and Decrease Costs with Custom e-Learning Content

It's no secret that software companies operate in a very... Read More

Microsoft Great Plains Project Accounting ? Overview For IT Director/Controller

Microsoft Business Solutions is now in process of creating so... Read More

.NET :Solving the Multiple Inheritance Issue Under .NET Platform

.NET platform does not support multiple inheritance. Do not confuse... Read More

How to Upgrade Dexterity Customization ? Tips for IT Manager

If you have Microsoft Great Plains and support it... Read More

Review of TikiWiki Content Management System

TikiWiki is open source software - it is written in... Read More

Groupware and Version History: Collaboration Series #1

This article is the first of a series of articles... Read More

About Microsoft Sysprep (System Preparation) Utility (Windows 2000)

The Microsoft system preparation utility for Windows 2000 is a... Read More

Microsoft Great Plains Security Setup - Overview For Consultant

Microsoft Business Solutions Great Plains is very good fit for... Read More

Reloading Windows XP

If you have been running Windows XP for a couple... Read More

Introduction To ISDN, Part II

In the previous ISDN article, we looked at how and... Read More

OSI Layers Model

IntroductionDuring the early years of our modern computer era, very... Read More

Anti-Spyware Protection ? Holes in the Shining Armor

Looking at all the ads which promise to get rid... Read More

Microsoft Great Plains: Service Business Customization & Integration Example

Microsoft Business Solutions Great Plains might be considered as ERP... Read More

Corel WordPerfect 7 Macro Programming Example

Case study: A secretary using Corel WordPerfect 7 is often... Read More

Microsoft CRM Programming Secrets ? Tips For Developers

This article is for advanced Microsoft CRM SDK C# developers.... Read More

Microsoft Great Plains: If You are Orphan Client ? What to Do and FAQ

Microsoft Business Solutions Great Plains, former Great Plains Software eEnterprise,... Read More

Free Program Removes Spyware not Detected by Premium Security Scan

What is Spyware?Spyware monitors your surfing habits and sends the... Read More

Microsoft Great Plains SOP: Sales Order Processing

Microsoft Business Solutions Great Plains is marketed for mid-size companies... Read More

SQL: Querying Microsoft Great Plains ? Overview for Database Administrator/Developer

Looks like Microsoft Great Plains becomes more... Read More

The Hidden Power of Online Manual

Writing software manuals is boring, isn't it? We often think:... Read More

Ukraine IT Myths Dispersed

While Ukraine is becoming a new popular IT outsourcing destination,... Read More

tidy up service Arlington Heights ..