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
There is a trick to make the Stream implementation calling close() after the terminal operation: List<String> rows = Stream.of(Files.lines(inputFilePath)).flatMap(s->s) .collect(Collectors.toList()); It simply creates a stream encapsulating the stream of lines as a single item and uses flatMap with an identity function (Function.identity() would work as well) to turn it into a stream of lines again. … 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
Try with resources can be used with multiple resources by declaring them all in the parenthesis. See the documentation Relevant code excerpt from the linked documentation: public static void writeToFileZipFileContents(String zipFileName, String outputFileName) throws java.io.IOException { java.nio.charset.Charset charset = java.nio.charset.StandardCharsets.US_ASCII; java.nio.file.Path outputFilePath = java.nio.file.Paths.get(outputFileName); // Open zip file and create output file with // try-with-resources … Read more
Based on Oracle’s tutorial, “[the resource] will be closed regardless of whether the try statement completes normally or abruptly”. It defines abruptly as from an exception. Returning inside the try is an example of abrupt completion, as defined by JLS 14.1.
Oracle explains how try-with-resources works here The TL;DR of it is: There is no simple way of doing this in Java 1.6. The problem is the absence of the Suppressed field in Exception. You can either ignore that and hardcode what happens when both try AND close throw different exceptions, or create your own Exception … Read more
To clarify the quote in Jon’s answer, only one exception can be thrown by a method (per execution) but it is possible, in the case of a try-with-resources, for multiple exceptions to be thrown. For instance one might be thrown in the block and another might be thrown from the implicit finally provided by the … Read more
It’s correct and there’s no requirement for catch clause. Oracle java 7 doc says the resource will be closed regardless of whether an exception is actually thrown or not. You should use a catch clause only if you want to react upon the exception. The catch clause will be executed after the resource is closed. … Read more
Here’s my take on the alternatives: 1) try (BufferedWriter bw = new BufferedWriter(new FileWriter(file))) { bw.write(text); } For me, the best thing coming to Java from traditional C++ 15 years ago was that you could trust your program. Even if things are in the muck and going wrong, which they often do, I want the … Read more
It was introduced because of some resources used in Java (like SQL connections or streams) being difficult to be handled properly; as an example, in java 6 to handle a InputStream properly you had to do something like: InputStream stream = new MyInputStream(…); try { // … use stream } catch(IOException e) { // handle … Read more