Final answer:
True, it's best practice to close the scanner stream when finished to prevent resource leaks and maintain predictable program behavior. Explicitly closing or using try-with-resources statement ensures system resources are released properly.
Step-by-step explanation:
The statement is true. It is a best practice to close the scanner stream when you have finished using it in Java. This is because scanner streams, like other resources such as file and network streams, use underlying system resources. Not closing these resources can lead to resource leaks, which can eventually exhaust system resources and cause your application to perform poorly or even fail. The scanner class has a close() method specifically for this purpose.
For example, if you open a scanner to read from a file with Scanner fileScanner = new Scanner(new File("file.txt"));, you should use fileScanner.close(); when you are done to release the system resources associated with the open file. If you do not close the scanner, it might keep the file locked, preventing other processes from accessing it. Moreover, in the context of garbage collection, relying on finalizers to implicitly close resources is not advisable, as there is no guarantee on when the garbage collector will run. Explicitly closing resources helps maintain predictable program behavior.
In modern Java versions, the try-with-resources statement simplifies resource management greatly by automatically closing resources that implement the AutoCloseable interface once the try block is exited, even if an exception is thrown. Using this feature, you can ensure that resources are always closed without having to manually include a close() call. For example: try (Scanner sc = new Scanner(System.in)) { /* use scanner */ }. This will ensure the scanner is closed automatically.