Catching Arguments Error Java Command Line
Contents |
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings
Java Command Line Arguments Parser
and policies of this site About Us Learn more about Stack Overflow java.exe command line arguments the company Business Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags java jar command line arguments Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only
Java Command Line Arguments Memory
takes a minute: Sign up Java program taking input from the command line, with exception handling up vote 1 down vote favorite need help again. The program is about taking input as age and throwing exception according to the input. It will take the age of the user from the command line as the program runs, the program should handle
Java Command Line Arguments Example
problems if the user does not input a number on the command line or makes an error in input. The code I have for this is: public class Age2 { public static void main(String args[]){ try{ int age = Integer.parseInt(args[0]); //taking in an integer input throws NumberFormat Exception if not an integer if(age<= 12) System.out.println("You are very young"); else if(age > 12 && age <= 20) System.out.println("You are a teenager"); else System.out.println("WOW "+age+" is old"); } catch(NumberFormatException e){ //is input is not an integer, occurs while parsing the command line input argument System.out.println("Your input is not a number"); }catch(ArrayIndexOutOfBoundsException e){ //as takes in input from command line which is stored to a Args array in main, if this array is null implies no input given System.out.println("Please enter a number on the command line"); } } }//end class The output I'm having: But the program also should show exception if the user makes any mistake like: "22 22" or "3 kjhk" see picture below: Could you please help me to modify this? Thanks all. java exception-handling share|improve this question asked A
my program. public static void main(String[] args) { ... // My program's code. } } (This code would be java command line arguments string stored in MyProgram.java, and compiled by running javac MyProgram.java.) To run this
Java Command Line Arguments Eclipse
Java code, you would invoke the Java Virtual Machine (JVM) with this command: java MyProgram The JVM would java command line arguments with spaces then load MyProgram.class, and begin executing your program with the main method. This is your program's entry-point. The main method must be declared in a specific way for the http://stackoverflow.com/questions/29627430/java-program-taking-input-from-the-command-line-with-exception-handling JVM to recognize it. It must be declared public and static, and it must take a single String[] argument and return no value (void). If your class doesn't have a main method with these exact characteristics, then you will get an error when you try to start your Java program: java MyProgram Exception in thread "main" java.lang.NoSuchMethodError: main If http://users.cms.caltech.edu/~donnie/cs11/java/java-main.html you see this error, make sure to check whether you have correctly declared your main method. The example code above declares the main method properly. Command-Line Arguments Frequently, a Java program needs to handle arguments specified on the command-line. For example, you might want to run your program like this: java MyProgram 1234 www.caltech.edu "olive festival" Somehow, your program needs to be able to access these values from the command-line. The way your program can do this is through the String[] argument passed to your main method. Note that the argument is an array of strings. Each element of the array contains one of the values specified on the command-line. In the above example, the args array will contain the following values: args.length = 3 args[0] = "1234" args[1] = "www.caltech.edu" args[2] = "olive festival" Java program arguments are separated by spaces and tabs, except when an argument is enclosed by double-quotes. For the above command-line invocation, the first two arguments are "1234" and "www.caltech.edu", since the Java VM will divide the argument list based
properties Javadoc (Current 1.4-SNAPSHOT) Javadoc (1.3.1) Project Documentation Project Information Project Reports Commons Home License Components Sandbox Dormant General Information Security https://commons.apache.org/cli/usage.html Volunteering Contributing Patches Building Components Commons Parent Pom Commons Build Plugin Releasing Components Wiki ASF How the ASF works Get Involved Developer Resources Sponsorship Thanks Usage Scenarios https://argparse4j.github.io/ The following sections describe some example scenarios on how to use CLI in applications. Using a boolean option A boolean option is represented on a command line command line by the presence of the option, i.e. if the option is found then the option value is true, otherwise the value is false. The DateApp utility prints the current date to standard output. If the -t option is present the current time is also printed. Create the Options An Options object must be created command line arguments and the Option must be added to it. // create Options object Options options = new Options(); // add t option options.addOption("t", false, "display current time"); The addOption method has three parameters. The first parameter is a java.lang.String that represents the option. The second parameter is a boolean that specifies whether the option requires an argument or not. In the case of a boolean option (sometimes referred to as a flag) an argument value is not present so false is passed. The third parameter is the description of the option. This description will be used in the usage text of the application. Parsing the command line arguments The parse methods of CommandLineParser are used to parse the command line arguments. There may be several implementations of the CommandLineParser interface, the recommended one is the DefaultParser. CommandLineParser parser = new DefaultParser(); CommandLine cmd = parser.parse( options, args); Now we need to check if the t option is present. To do this
available in Maven central repository: