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What are some real life examples to understand the key role of assertions?
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assert is a Java keyword used to define an assert statement. An assert statement is used to declare an expected boolean condition in a program. If the program is running with assertions enabled, then the condition is checked at runtime. If the condition is false, the Java runtime system throws an AssertionError .
An assertion is a statement in Java which ensures the correctness of any assumptions which have been done in the program. When an assertion is executed, it is assumed to be true. If the assertion is false, the JVM will throw an Assertion error. It finds it application primarily in the testing purposes.
Assertions should be used to check something that should never happen, while an exception should be used to check something that might happen. For example, a function might divide by 0, so an exception should be used, but an assertion could be used to check that the harddrive suddenly disappears.
Assertions are used to codify the requirements that render a program correct or not by testing conditions (Boolean expressions) for true values, and notifying the developer when such conditions are false. Using assertions can greatly increase your confidence in the correctness of your code.
Assertions (by way of the assert keyword) were added in Java 1.4. They are used to verify the correctness of an invariant in the code. They should never be triggered in production code, and are indicative of a bug or misuse of a code path. They can be activated at run-time by way of the -ea option on the java command, but are not turned on by default.
An example:
public Foo acquireFoo(int id) { Foo result = null; if (id > 50) { result = fooService.read(id); } else { result = new Foo(id); } assert result != null; return result; } If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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