try-with-resources

I have two versions of Java code that gets user input until user types "q" Version 1: public class Test { public static void main(String[] args) { String input = ""; while (!input.equals("q")) { Scanner scanner = new Scanner(System.in); System.out.print("Input: "); input = scanner.nextLine(); System.out.println("Input was: " + input); } } } Version 2: public class Test { public static void main(String[] args) { String input = ""; while (!input.equals("q")) { try(Scanner scanner = new Scanner(System.in)){ System.out.print("Input: "); input = scanner.nextLine(); System.out.println("Input was: "

I've read this topic , and this blog article about try with resources locks, as the question popped in my head. But actually, what I'd rather like would be a try with lock , I mean without lock instantiation. It would release us from the verbose lock.lock(); try { //Do some synchronized actions throwing Exception } finally { //unlock even if Exception is thrown lock.unlock(); } Would rather look like : ? implements Unlockable lock ; ... try(lock) //implicitly calls lock.lock() { //Do some synchronized actions throwing Exception } //implicitly calls finally{lock.unlock();} So it would not be a

原本同步至 http://www.waylau.com/concise-try-with-resources-jdk9/ 本文详细介绍了自 JDK 7 引入的 try-with-resources 语句的原理和用法，以及介绍了 JDK 9 对 try-with-resources 的改进，使得用户可以更加方便、简洁的使用 try-with-resources 语句。 在 JDK 7 之前，资源需要手动关闭。 例如下面一个很常见的文件操作的例子： Charset charset = Charset.forName("US-ASCII"); String s = ...; BufferedWriter writer = null; try { writer = Files.newBufferedWriter(file, charset); writer.write(s, 0, s.length()); } catch (IOException x) { System.err.format("IOException: %s%n", x); } finally { if (writer != null) writer.close(); } 在 JDK 7 之前，你一定要牢记在 finally 中执行 close 以释放资源 JDK 7 中的 try-with-resources 介绍

1、旧社会 Java里，对于文件操作IO流、数据库连接等开销非常昂贵的资源，用完之后必须及时通过close方法将其关闭，否则资源会一直处于打开状态，直至程序停止，增加系统负担。 关闭资源的常用方式就是在finally块里是释放，即调用close方法。比如，我们经常会写这样的代码： public static void main(String[] args) { BufferedReader br = null; try { String line; br = new BufferedReader(new FileReader("d:\\testing.txt")); while ((line = br.readLine()) != null) { System.out.println(line); } } catch (IOException e) { // handle exception } finally { try { if (br != null) { br.close(); } } catch (IOException ex) { // handle exception } } } 可以看出，为了关闭资源以及处理关闭资源时可能出现的异常，不得不写一大推代码。 2、新时代 2.1 使用新写法 从Java 7开始，jdk提供了一种更好的方式关闭资源，使用try-with

In Scala application, am trying to read lines from a file using java nio try-with-resource construct. Scala version 2.11.8 Java version 1.8 try(Stream<String> stream = Files.lines(Paths.get("somefile.txt"))){ stream.forEach(System.out::println); // will do business process here }catch (IOException e) { e.printStackTrace(); // will handle failure case here } But the compiler throws error like ◾not found: value stream ◾A try without a catch or finally is equivalent to putting its body in a block; no exceptions are handled. Not sure what is the problem. Am new to using Java NIO, so any help is

Why is Eclipse giving a strange "Resource leak: zin is never closed" warning for the following code even though I use try-with-resources : Path file = Paths.get("file.zip"); // Resource leak warning! try (ZipInputStream zin = new ZipInputStream(Files.newInputStream(file))) { for (int i = 0; i < 5; i++) if (Math.random() < 0.5) throw new Exception(); } catch (Exception e) { e.printStackTrace(); } If I modify "anything" on the code, the warning goes away. Below I list 3 modified versions which are all OK (no warnings). Mod #1: If I remove the for loop from the try block, the warning goes away: /