Assertions
In this lesson, we will explore another way to find logical errors in a program.
We'll cover the following...
What is an assertion?
An assertion is a statement of truth about some aspect of our program’s logic. You can think of it as a Boolean expression that is true, or that at least should be true, at a certain point. If an assertion is false, something is wrong with our program. We can state assertions as comments within our code. For example, if at some point in a method’s definition we know that the variable sum should be positive, we could write the following comment:
// Assertion: sum > 0
Such comments point out aspects of the logic that might not be clear. Additionally, they provide places for us to check the accuracy of our code during debugging.
The assert statement
Java enables us to do more than simply write a comment to make an assertion. We can use an assert statement, such as:
assert sum > 0;
to enforce the assertion. If the Boolean expression that follows the reserved word assert is true, the statement does nothing. If it is false, an assertion error occurs and program ...