try-catch

问题 I am trying to use the try() function to deal with errors that are occurring in my parallelised for loop: results <- foreach (i = 1:2, .errorhandling = 'remove') %dopar% { res <- try(myfun(i), TRUE) } with myfun <- function(i){ if (i==1) return(rnorm(1)) else stop('error') } I get the following error message Error in checkForRemoteErrors(val) : one node produced an error: Error in myfun(i) : error How can I get the foreach "loop" to ignore the error message (or at least deal with it a little

问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: try/catch + using, right syntax I would like to try/catch the following: //write to file using (StreamWriter sw = File.AppendText(filePath)) { sw.WriteLine(message); } Do i put the try/catch blocks inside the using statement or, around it? Or both? 回答1: If your catch statement needs to access the variable declared in a using statement, then inside is your only option. If your catch statement needs the object

问题 I'm using try catch on a node.js script: try {} catch (err) {console.log(err)} I get an output like this: { stack: [Getter/Setter], arguments: [ 'undefined' ], type: 'called_non_callable', message: [Getter/Setter] } Is there an easy way to make this more informative? Include line numbers and function names and such? 回答1: Those [Getter/Setter] members indicate further information available on the error object. You can easily dump the contents of those getters/setters using a small helper

问题 I have a simple question hopefully - how does one free memory which was allocated in the try block when the exception occurs? Consider the following code: try { char *heap = new char [50]; //let exception occur here delete[] heap; } catch (...) { cout << "Error, leaving function now"; //delete[] heap; doesn't work of course, heap is unknown to compiler return 1; } How can I free memory after the heap was allocated and exception occurred before calling delete[] heap ? Is there a rule not to

问题 This question already has answers here : Does a finally block always get executed in Java? (47 answers) Closed 5 years ago . The output of the following piece of code is "Test Passed"; can someone explain to me why ? public class Test { public static void main(String args[]) { System.out.println(new Test().print()); } protected StringBuilder print() { StringBuilder builder = new StringBuilder(); try { builder.append("Test "); return builder.append("Passed!!!"); } finally { builder = null; } }

问题 This question already has answers here : Does a finally block always get executed in Java? (47 answers) Closed 6 years ago . Given the following try/catch block in java: try{ return; } catch(SomeException e){ System.out.println(e); } finally{ System.out.println("This is the finally block"); } and according to this post: "Does finally always execute in Java?" I can see that the program's output will be 'This is the finally block'. However, I can't figure out how that would be possible since

问题 I often see catch clauses for Throwable in Blackberry documentation, such as the Network API docs. My sense is that this is not generally a good practice in Java. Is there a reason for this in Blackberry programming? Does it have to do with stack trace generation for Throwables? 回答1: When you catch Throwable in a BlackBerry app, not only does it preserve the stack trace, it saves that stack trace in the device event log. There is no way for an app to get a stack trace itself, so unfortunately

问题 I am looking for the best way to do exception handling, for example.. when an error occurs in the business logic layer, is the best way to stop the METHOD using a catch and return an EVENT to the presentation layer? What should this event contain? Or should i always BUBBLE up exceptions and handle them in the presentation layer? Anyone have some good links and required reading on this with regards to the best way of handling exceptions and how to handle them in the client ... For example if i

问题 I noticed that when the following variables when in try { }, I couldn't use methods on them from finally for example: import java.io.*; public class Main { public static void main()throws FileNotFoundException { Try{ File src = new File("src.txt"); File des = new File("des.txt"); /*code*/ } finally{ try{ /*closing code*/ System.out.print("After closing files:Size of src.txt:"+src.length()+" Bytes\t"); System.out.println("Size of des.txt:"+des.length()+" Bytes"); } catch (IOException io){

问题 I noticed that when the following variables when in try { }, I couldn't use methods on them from finally for example: import java.io.*; public class Main { public static void main()throws FileNotFoundException { Try{ File src = new File("src.txt"); File des = new File("des.txt"); /*code*/ } finally{ try{ /*closing code*/ System.out.print("After closing files:Size of src.txt:"+src.length()+" Bytes\t"); System.out.println("Size of des.txt:"+des.length()+" Bytes"); } catch (IOException io){