How To Fix Assertion Error In Java

What is Assertion in Coffee?

The assertion in Java is used to ensure the correctness of whatever program's assumptions equally the exclamation is causeless to be true when it is executed. The Java Virtual Machine throws an fault named AssertionError if the assertion is imitation. The assertion in Coffee has found its awarding mainly for testing purposes. Boolean expressions are used along with assertion statements. An assertion is a argument, and the 'nugget' keyword is used to acquit out an exclamation in Java.

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Syntax

The following are ii ways in which assertion is carried out in Java:

one. assert expression;

2. affirm expression1: expression2;

How to Utilize Exclamation in Java?

Assertions are disabled in Java past default. The post-obit command is used to enable them:

java -ea Exam

(or)

coffee -enableassertions Test

where Test is the name of the Java file.

Here is an instance to demonstrate the syntax of assertion:

public grade Test

{

public static void main(String[] args)

{

int value = xiii;

assert value <= 12 : "Not Teen";

System.out.println("The age of teenager is " + value);

}

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Output

Here is an case for the generation of an assertion error past the Java Virtual Auto –

form Exam

{

public static void main( String args[] )

{

int weight = thirty;

affirm weight >= 20 : " Overweight";

System.out.println("Weight is "+value);

}

Output

After enabling assertions,

Output

Exception in thread "main" java.lang.AssertionError: Overweight

This is what it looks like:

Source

Why Employ Assertions?

The assertion in Coffee is used to:

Cheque if the assumptions made past the programmer are correct or non.
Make sure that if the code looks unreachable, information technology is unreachable.
Confirm that assumptions written in the comments are correct, for instance:

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if ((y & 1) == 1)

{ }

else // y must be fifty-fifty

{ assert (y % 2 == 0); }

ensure default switch case is not being reached
check the state of the object

The assertion in Java is used at the beginning of the method and after the method invocation.

Where to use Assertions?

The assertion in Coffee is used in provisional cases and when conditions are at the beginning of whatsoever method. Also, in the example of arguments to private methods. The developer's code provides private arguments and when the programmer needs to check his/her assumptions regarding the arguments.

Here are some situations in which the use of assertions should be avoided:

As per the specifications given by Sun Microsystems, the exclamation should not be used while checking arguments in the public methods because that would result in appropriate runtime exceptions such as NullPointerException and IllegalArgumentException.
It should not be used every bit a replacement to mistake messages.
If you practise not want any error to arise in any situation, skip using assertion.
Information technology should not be used on command-line arguments.
If the user provides errors, assertions should not exist used to check arguments in public methods. Instead, error handling should be used.

How to Disable Assertions?

The following commands are used to disable assertion in Java:

java –da Exam

java – disableassertions Examination

where Test is the name of the Coffee file.

Ways to use Exclamation in Coffee

Example 1: Java assertion

public grade Main {

public static void main(String args[]) {

Cord[] weekdays = {"Mon", "Tue", "Wed","Thur","Fri"};

assert weekdays.length == 2;

System.out.println("There are " + weekdays.length + " weekdays in a calendar week");

}

Output

The following output is achieved when assertions are disabled and the program has no compilation errors.

When the assertions are enabled, nosotros will go the following output:

Exception in thread "main" java.lang.AssertionError

At that place is another form of assertion statement which is as follows:

assert status: expression;

This class of exclamation statement has an expression that is passed to the AssertionError object'southward constructor. If the condition is false, this expression has a value displayed equally the mistake'southward detail message. To assistance in debugging the problem, the detailed massaged captures and transmits the exclamation failure data.

Example 2: Java assertion with expression case

public class Main {

public static void main(Cord args[]) {

String[] weekdays = {"Monday", "Tue", "Midweek","Thur","Fri", "Sabbatum"};

affirm weekdays.length == 5: "There are but 5 weekdays in a week";;

Arrangement.out.println("There are " + weekdays.length + " weekdays in a week");

}

Output

Exception in thread "chief" java.lang.AssertionError: There are just 5 weekends in a week

As shown in the above case, the expression is passed to the AssertionError object's constructor. As the assertions are enabled and the assumption is imitation, an appropriate message is displayed when an exception is thrown. The message helps to diagnose and fix the error that caused the failure of the exclamation.

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Determination

In this blog, yous have learned how to utilise assertions to exam the program logic. You lot have likewise learned why assertions cannot exist used equally a replacement for exceptions, and yous have seen situations where using an exception would be more effective than exception handling.

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What is assertion in Java?

In Coffee programming language, assertion is a method used for ensuring that some requirements should be followed. The assertion failure in Coffee is considered every bit compilation error, i.e. if at that place are whatsoever assertions in your code, the code won't exist compiled, and you will become error message. This feature of Coffee enables y'all to protect your code from unexpected or unwanted run-fourth dimension errors. The Java assert statement allows you to test invariants of your programme at run time. Assertions are normally used to check that the code is not inbound an invalid state. In other languages you lot may encounter contract methods or pre/mail atmospheric condition used for this purpose.

How to handle exceptions in Coffee?

An exception is a runtime error, meaning information technology occurs while the program is running, non during compilation. The exception is thrown when an error has occurred and the programme cannot continue. You can handle exceptions in iii unlike ways: Ignore the exception and permit the programme to go out. Apply the throw keyword to rethrow the exception. Apply the try-grab block to handle the exception. You tin can log or impress the exception and then allow the program exit. You can employ the get out keyword to terminate the programme. You lot can use the throw keyword to rethrow the exception. You can utilize the try-catch block to handle the exception. In that location's a catch block that accepts the exception in its statement. At that place's a finally block that runs whether an exception is thrown or not.

How does endeavor-grab work in Java?

try-catch is a mechanism in Java that allows you to define a telescopic in which you tin deal with runtime errors in a controlled manner. It also ensures that the menses of execution doesn't stop completely when an error is encountered. try and catch are two keywords used to implement exception handling. Whenever an error occurs in your plan, the attempt block volition be executed, and the error will and then exist handled by the catch cake.

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