Home
>
Software
>
Assertion in Java

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The withdrawMoney method has a assert statement that checks whether the balance is grater than or equal to amount to be withdrawn.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

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

best cleaning company Lincolnshire ..

In The News:

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.

Scammers nearly stole an Apple account by exploiting the support system with authentic-looking tickets and phone calls, users can protect themselves with safety steps.

FoloToy restored sales of its AI teddy bear Kumma after a weeklong suspension following safety group findings of risky and inappropriate responses to children.

Threat intelligence firm Synthient uncovers one of the largest password exposures ever, prompting immediate security recommendations.

Viral video shared by Elon Musk shows Tesla's Optimus humanoid robots performing tasks from cooking to construction, garnering over 58.5 million views on social media.

Chinese hackers used Anthropic's Claude AI to launch autonomous cyberattacks on 30 organizations worldwide, marking a major shift in cybersecurity threats.

Apple's new Sleep Score feature gives you a rating for your nightly rest quality. Learn how to set it up on your Apple Watch and iPhone today.

Assertion in Java

Software