What effect does declaring a variable as final have in Java?

Declaring a variable as final in Java signifies that once the variable has been assigned a value, that value cannot be changed or modified. This immutability applies to the reference held by the variable, meaning that the variable cannot be reassigned to point to a different object or value after its initial assignment.

For instance, if you declare a final variable as an integer and set it to a value of 10, you would not be able to later assign it a new value like 20. However, it's important to note that if the final variable refers to an object, you can still modify the internal state of that object, but you cannot reassign the variable to point to a different object.

Understanding this concept is crucial in programming because final variables can create more predictable and safer code, as they prevent unintentional changes to that variable throughout the program. This feature is commonly used when defining constants, where the value should remain consistent across the application.