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2024.3

AutoCloseable used without 'try'-with-resources

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Last modified: 03 December 2024

Reports AutoCloseable instances which are not used in a try-with-resources statement, also known as Automatic Resource Management.

This means that the "open resource before/in try, close in finally" style that had been used before try-with-resources became available, is also reported. This inspection is meant to replace all opened but not safely closed inspections when developing in Java 7 and higher.

Example:

Use the following options to configure the inspection:

  • List subclasses of AutoCloseable that do not need to be closed and should be ignored by this inspection.

    Note: The inspection will still report streams returned from the java.nio.file.Files methods lines(), walk(), list() and find(), even when java.util.stream.Stream is listed to be ignored. These streams contain an associated I/O resource that needs to be closed.

  • List methods returning AutoCloseable that should be ignored when called.

  • Whether to ignore an AutoCloseable if it is the result of a method call. When this option is enabled, the results of factory methods will also be ignored.

  • Whether the inspection should report if an AutoCloseable instance is passed as a method call argument. If this option is enabled, the inspection assumes the resource is closed in the called method. Method calls inside a finally block with 'close' in the name and an AutoCloseable argument will not be ignored.

  • Whether to ignore method references to constructors of resource classes.

  • Whether to ignore methods that return a resource and whose name starts with 'get'. This can reduce false positives because most of the getters do not transfer the ownership of the resource, and their call sites are not responsible for closing the resource.

This inspection depends on the Java feature 'Try-with-resources', which is available since Java 7.