try-with-resources

问题 I'm having a warning message constantly, despite my code seems to be good. The message is: WARNING: A connection to http://someurl.com was leaked. Did you forget to close a response body? java.lang.Throwable: response.body().close() at okhttp3.internal.platform.Platform.getStackTraceForCloseable(Platform.java:148) at okhttp3.RealCall.captureCallStackTrace(RealCall.java:89) at okhttp3.RealCall.execute(RealCall.java:73) at com.example.HTTPSClientReferenceRate.runClient(HTTPSClientReferenceRate

问题 Since Java 7, we can use try with resources: try (One one = new One(); Two two = new Two()) { System.out.println("try"); } catch (Exception ex) { ... } Now my question is, why do I have to create the object in the try -statement? Why am I not allowed to create the object before the statement like this: One one = new One(); try (one; Two two = new Two()) { System.out.println("try"); } catch (Exception ex) { ... } I don't see any reasons, why this should be a problem. Though I get the error

问题 Since Java 7, we can use try with resources: try (One one = new One(); Two two = new Two()) { System.out.println("try"); } catch (Exception ex) { ... } Now my question is, why do I have to create the object in the try -statement? Why am I not allowed to create the object before the statement like this: One one = new One(); try (one; Two two = new Two()) { System.out.println("try"); } catch (Exception ex) { ... } I don't see any reasons, why this should be a problem. Though I get the error

问题 It is unclear from the documentation if a catch following a try-with-resources covers the initialization part or not. In other words, given this code fragment: try (InputStream in = getSomeStream()) { System.out.println(in.read()); } catch (IOException e) { System.err.println("IOException: " + e.getMessage()); } Would my catch be invoked if an IOException is thrown inside getSomeStream() ? Or does the catch only cover the block inside curly braces, i.e. System.out.println(in.read()) ? 回答1:

问题 It is unclear from the documentation if a catch following a try-with-resources covers the initialization part or not. In other words, given this code fragment: try (InputStream in = getSomeStream()) { System.out.println(in.read()); } catch (IOException e) { System.err.println("IOException: " + e.getMessage()); } Would my catch be invoked if an IOException is thrown inside getSomeStream() ? Or does the catch only cover the block inside curly braces, i.e. System.out.println(in.read()) ? 回答1:

问题 I have looked around, but can't seem to find the answer to my question. Here is the context : I have to connect to a Database in my Java program and execute a SQL request that I have no control over and don't know in advance. To do that I use the code below. public Collection<HashMap<String, String>> runQuery(String request, int maxRows) { List<HashMap<String, String>> resultList = new ArrayList<>(); DataSource datasource = null; try { Context initContext = new InitialContext(); datasource =

问题 I am rewriting my AudioManager class for my school project and I encountered a problem. My professor told me to load all my resources with the Try-with-resources block instead of using try/catch ( See code below ). I am using the Clip class from javax.sound.sampled.Clip and everything works perfectly with my PlaySound(String path) method that uses try/catch/ if I don't close() the Clip. I know that if I close() the Clip I can't use it anymore. I have read the Oracle Docs for Clip and Try-with

问题 I have the simple code: try (FileReader file = new FileReader(messageFilePath); BufferedReader reader = new BufferedReader(file)) { String line; while ((line = reader.readLine()) != null) { //// } } I want to write something like that: FileReader file = null; ///..... try(file = (file == null ? new FileReader(messageFilePath) : file); BufferedReader reader = new BufferedReader(file)) { String line; while ((line = reader.readLine()) != null) { //// } } It is allows me to reuse FileReader . Is

问题 I have a Java application where I use Akka Typed Actors. The code has no errors in Eclipse, but when I start my application it crashes and prints this error: Exception in thread "main" java.lang.VerifyError: Inconsistent stackmap frames at branch target 266 in method com.example.actors.DBActor.getItems(Lorg/joda/time/DateTime;Lorg/joda/time/DateTime;)I at offset 170 at com.example.ui.Main$1.create(Main.java:31) at akka.actor.TypedActor$$anonfun$newInstance$3.apply(TypedActor.scala:677) at

问题 I was reading about the try-with-resource in JDK7 and while I was thinking of upgrading my application to run with JDK7 I faced this problem.. When using a BufferedReader for example the write throws IOException and the close throws IOException.. in the catch block I am concerned in the IOException thrown by the write.. but I wouldn't care much about the one thrown by the close.. Same problem with database connections.. and any other resource.. As an example I've created an auto closeable