It is optional if close() is not able to throw a checked exception. However, if close() can, then a checked exception would need to handled in a normal fashion, either with a catch block, or by throwing from the method that try-with-resources block is in. More details are in JLS 14.2.3 14.20.3.2. Extended try-with-resources A … Read more
An instance variable may be changed at any point during the execution of the try-with-resources block. This would break its invariant and prevent the cleanup. Note that the local variable is implictly final, for the same reason. BTW a better question is, why does Java force us to declare a local variable, even if we … Read more
Closeable and AutoCloseable are general-purpose interfaces that do not know anything about flushing. So you can’t find any information about it in their documentation – except some words about releasing resources. A Writer on the other hand is a more specific-purpose abstract class that now knows something about flushing. Some excerpt of the documentation for … Read more
try(Connection con = getConnection()) { try (PreparedStatement prep = con.prepareConnection(“Update …”)) { //prep.doSomething(); //… //etc con.commit(); } catch (SQLException e) { //any other actions necessary on failure con.rollback(); //consider a re-throw, throwing a wrapping exception, etc } } According to the oracle documentation, you can combine a try-with-resources block with a regular try block. IMO, … Read more
I found this answered on the coin-dev mailing list: http://mail.openjdk.java.net/pipermail/coin-dev/2009-April/001503.html 5. Some failures of the close method can be safely ignored (e.g., closing a file that was open for read). Does the construct provide for this? No. While this functionality seems attractive, it is not clear that it’s worth the added complexity. As a practical … Read more
The resource gets closed before catch or finally blocks. See this tutorial. A try-with-resources statement can have catch and finally blocks just like an ordinary try statement. In a try-with-resources statement, any catch or finally block is run after the resources declared have been closed. To evaluate this is a sample code: class ClosableDummy implements … Read more
That ExecutorService has actually two shutdown-related methods; based on the simple fact that both ways of shutting down a service make sense. Thus: how would you auto-close a service then? In a consistent manner that works for everybody?! So, the reasonable explanation in my eyes: you can’t make an ExecutorService a AutoClosable because that service … Read more
The main point of try-with-resources is to make sure resources are closed reliably without possibly losing information. When you don’t use try-with-resources there’s a potential pitfall called exception-masking. When code in a try block throws an exception, and the close method in the finally also throws an exception, the exception thrown by the try block … Read more
Try with resources can be used with multiple resources by declaring them all in the try block and this feature introduced in java 7 not in java 8 If you have multiple you can give like below try ( java.util.zip.ZipFile zf = new java.util.zip.ZipFile(zipFileName); java.io.BufferedWriter writer = java.nio.file.Files.newBufferedWriter(outputFilePath, charset) ) { // Enumerate each entry … Read more
Click on the File menu, open Project Structure, then under “Settings” there should be “Project”. Within that tab, there’ll be an SDK Settings option which specifies the language version you want to use. See the JetBrains help page for more details (“Project language level”).