Java Assert – Why We Use Assertion in Java

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1. Objective

In our last session, we discussed Java Image Processing. Here, in this Java Assert tutorial, we are going to learn about the what is an assertion in Java. Moreover, we will study how to enable assertion in Java and disable, Why to use Java assertions, a difference between Java assertion vs. normal exception handling. At last, we will discuss where to utilize assertion in Java or not and assertion example.

So, let us start Java Assert.

Java Assert - Why We Use Assertion in Java

Java Assert – Why We Use Assertion in Java

2. What is Java Assert?

An assertion in Java helps to check how the assumptions made during programs are correct. An assertion is accomplished utilizing the assert proclamation in Java. While executing Java assertion, it is accepted to be valid. On the off chance that it comes up short, JVM (Java Virtual Machine) tosses a mistaken name AssertionError. Java Assert basically utilizes for testing purposes amid advancement.

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Java asserts statement utilize with a Boolean articulation and can compose in two diverse ways.

  • Assert expression;
  • Assert expression1: expression2;

Example –

import java.util.Scanner;
class Test
    public static void main( String args[] )
        int value = 15;
        assert value >= 20 : " Underweight";
        System.out.println("value is "+value);

a. Enabling and Disabling Assertions in Java

  • Java Assert is enabled by default, the syntax for the same is-
java –ea Test


java –enableassertions Test
  • The syntax for disabling Java Assert-
java –da Test


java –disableassertions Test

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b. Why use Java Assertion

Wherever a software engineer needs to check whether his/her suspicions aren’t right or not.

  • To ensure that an inaccessible looking code is really inaccessible.
  • Ensure that presumptions written in remarks are correct.
  • To do beyond any doubt default switch case isn’t come to.
  • Check the protest’s state.
  • At the start of the strategy
  • After strategy summon.
  if ((x & 1) == 1) 
         {  }
         else // x must be even
         { assert (x % 2 == 0); }

c. Java Assertion vs. Normal Exception Handling

Assertions are primarily use to check logically inconceivable circumstances. For instance, Java Assert can utilize to check the express a code expects before it begins pursuing or state it completes the process of running. Not at all like ordinary special case/mistake taking care of, are declarations for the most part disabled at run-time.

Let’s Discuss Exception Handling in Java

d. Where to Utilize Assertion in Java

Java Assert is utilizing in the following ways;

  • Java Assertions of private techniques. Private contentions are given by designer’s code just an engineer might need to check his/her suppositions about contentions.
  • Restrictive cases.
  • Conditions toward the start of any technique.

e. Where Not to Utilize Assertion in Java

  • Assertions in Java, ought not to utilize to supplant error messages
  • Java Assertions ought not to utilize to check contentions in the general population strategies as they may give by a client. Mistake dealing with ought to utilize to deal with blunders given by a client.
  • Assertions ought not to utilize in summoning line arguments.

So, this was all about Java Assert Tutorial. Hope you like our explanation of Assertion in Java.

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3. Conclusion

Hence, in this Java tutorial, we study what is an assertion in Java, enabling and disabling assertion in Java, why use Java assertion. Also, we studied a difference between Java assertion vs. normal exception handling and utilization of assertion in Java. In conclusion, we discussed some Java Assert example, and in the next tutorial, we will study Java Annotations. Furthermore, if you have any query feel free to ask in a comment section.

Related Topic – Difference Between Checked vs Unchecked Exceptions in Java

For reference

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