This program only deals with one file. However, it is good practice to remember to close every external resource. That includes files, database connections (and other related resources, like prepared statements and result sets), network sockets, etc. not closing resources may result in resource leaks that can escalate to JVM crash. Java 7 introduced the try-with-resources construct that allows the compiler to automatically handle resource closure as well as error handling.

Java 7 also introduced the "new io" java.nio package that improves IO handling in Java. the Files.readAllLines() is a convenient method that reads whole file into List of Strings (and also internally handles the external resource).

This program only deals with one file. However, it is good practice to remember to close every external resource. That includes files, database connections (and other related resources, like prepared statements and result sets), network sockets, etc. not closing resources may result in resource leaks that can escalate to JVM crash. Java 7 introduced the try-with-resources construct that allows the compiler to automatically handle resource closure as well as error handling.

Java 7 also introduced the "new io" java.nio package that improves IO handling in Java. the Files.readAllLines() is a convenient method that reads whole file into List of Strings (and also internally handles the external resource). (alas, no equivalent writeAllLines())