try-catch

问题 When I'm developing normal web application with JavaScript, the try/catch statement is not needed usually. There's no checked exception, File IO or database connection in JavaScript. Is try/catch statement useful in JavaScript? When can I use it? 回答1: Use it whenever code you are running might throw an exception. Remember that you can throw your own errors — most of the try…catch stuff I use is for catching my own exceptions. 回答2: try...catch blocks are generally encourages to be used less,

问题 Identical to "How do exceptions work (behind the scenes) in C++", but for C# . I know that the steps below have to be performed when an exception is thrown. Find the nearest handler for the exception type; Unwind the stack up to the handler level; Call the handler; Find and call every finally blocks. How does .NET handles these operations? How does the mapping for the "current" handlers work? How much code is emitted in a try/catch block? And in a throw block? 回答1: Read Christopher Brumme's

问题 Identical to "How do exceptions work (behind the scenes) in C++", but for C# . I know that the steps below have to be performed when an exception is thrown. Find the nearest handler for the exception type; Unwind the stack up to the handler level; Call the handler; Find and call every finally blocks. How does .NET handles these operations? How does the mapping for the "current" handlers work? How much code is emitted in a try/catch block? And in a throw block? 回答1: Read Christopher Brumme's

问题 My function needs one argument words, but i want the program not to crash if no argument. def get_count(words): try: consonants_str = "bcdfghjklmnpqrstvwxyzBCDFGHJKLMNPQRSTVWXYZ" vowels_str = "aeiouAEIOU" consonants_ls = [] vowels_ls = [] words_ls = [] result = {"vowels": 0, "consonants": 0}` for element in consonants_str: consonants_ls.append(element) for element in vowels_str: vowels_ls.append(element) if type(words) != type(None): for element in words: words_ls.append(element) for element

问题 My function needs one argument words, but i want the program not to crash if no argument. def get_count(words): try: consonants_str = "bcdfghjklmnpqrstvwxyzBCDFGHJKLMNPQRSTVWXYZ" vowels_str = "aeiouAEIOU" consonants_ls = [] vowels_ls = [] words_ls = [] result = {"vowels": 0, "consonants": 0}` for element in consonants_str: consonants_ls.append(element) for element in vowels_str: vowels_ls.append(element) if type(words) != type(None): for element in words: words_ls.append(element) for element

问题 My function needs one argument words, but i want the program not to crash if no argument. def get_count(words): try: consonants_str = "bcdfghjklmnpqrstvwxyzBCDFGHJKLMNPQRSTVWXYZ" vowels_str = "aeiouAEIOU" consonants_ls = [] vowels_ls = [] words_ls = [] result = {"vowels": 0, "consonants": 0}` for element in consonants_str: consonants_ls.append(element) for element in vowels_str: vowels_ls.append(element) if type(words) != type(None): for element in words: words_ls.append(element) for element

问题 How do you loop a try/catch statement? I'm making a program that is reading in a file using a Scanner and it's reading it from the keyboard. So what I want is if the file does not exist, the program will say "This file does not exist please try again." then have the user type in a different file name. I have tried a couple different ways to try an do this but, all of my attempts end up with the program crashing. Here is what I have try { System.out.println("Please enter the name of the file:

问题 This question already has answers here : Why doesn't Java allow to throw a checked exception from static initialization block? (8 answers) Closed 5 years ago . In a hypothetical situation I have a class like this: import java.io.File; import java.util.Scanner; class X { static Scanner scanner; static { scanner = new Scanner(new File("X.txt")); } } When compiling, I get unreported exeption java.io.FileNotFoundException ; must be caught or declared to be thrown because public Scanner(File

问题 I have the below code with which i am able to print the fullclassname,classname,methodname, at which error occured. Also, I am able to print Line-Number but the Line-Number printed is the line at which the variable "LineNumber" is initialized. How can i print the exact LineNumber and ColumnNumber in try block at which error occured? try { SQL Query } catch(Exception e) { String fullClassName = Thread.currentThread().getStackTrace()[1].getClassName(); String className = fullClassName.substring

问题 In PHP, how do variable scope rules apply to Try/Catch blocks? Do variables declared within the try block go out of scope when the block has finished? Or are they in scope until the end of the function/method? For example: try { // This may throw an exception when created! $o = new Pronk(); } catch (Exception $ex) { // Handle & exit somehow; not important here return false; } $o->doPronk(); Is this valid? Or should $o = NULL; be set before the try/catch to keep $o in scope? (I know that the