javacommand-line-interfaceapache-commons-cli

Apache command line parser bug?


I got the code below from a sample code from tutorials point and tweaked it a little bit.

App.java

public static void main(String[] args) throws ParseException {
        CommandTest t = new CommandTest();
        t.start(args);
}

CommandTest.java

public class CommandTest {

    void start(String[] args) throws ParseException {

          //***Definition Stage***
          // create Options object
          Options options = new Options();

          // add option "-a"
          options.addOption(
                    Option.builder("a")
                        .longOpt("add")
                        .desc("add numbers")
                        .hasArg(false)
                        .valueSeparator('=')
                        .required(false)
                        .build()
                  );

          // add option "-m"
          options.addOption("m", false, "");
          options.addOption(
                    Option.builder("m")
                        .longOpt("multiply")
                        .desc("multiply numbers")
                        .hasArg(false)
                        .valueSeparator('=')
                        .required(false)
                        .build()
                  );

          //***Parsing Stage***
          //Create a parser
          CommandLineParser parser = new DefaultParser();

          //parse the options passed as command line arguments
          CommandLine cmd = parser.parse( options, args);

          //***Interrogation Stage***
          //hasOptions checks if option is present or not
          if(cmd.hasOption("a")) { 
             System.out.println("Sum of the numbers: " + getSum(args));
          } else if(cmd.hasOption("m")) {
             System.out.println("Multiplication of the numbers: " + getMultiplication(args));
          }
       }

       public static int getSum(String[] args) {
          int sum = 0;
          for(int i = 1; i < args.length ; i++) {
             sum += Integer.parseInt(args[i]);
          } 
          return sum;
       }

       public static int getMultiplication(String[] args) {
          int multiplication = 1;
          for(int i = 1; i < args.length ; i++) {
             multiplication *= Integer.parseInt(args[i]);
          } 
          return multiplication;
       }
}

Now, my question is that, when i try to execute the above code with a parameter of -multi it will still be accepted? I've already set the options to receive only either -m or -multiply. However, it will still accept -multi

I am using commons-cli-1.3.1 (im trying to debug a legacy code by the way)

Note: Above source is a SAMPLE source only, no need to apply actual coding guidelines (good or bad) i just want to know why the behavior happens as it is.


Solution

  • This is the behaviour when a non-matching option gets found (org.apache.commons.cli.Options:233):

    public List<String> getMatchingOptions(String opt) {
      opt = Util.stripLeadingHyphens(opt);
      List<String> matchingOpts = new ArrayList();
      if (this.longOpts.keySet().contains(opt)) {
        return Collections.singletonList(opt);
      } else {
        Iterator var3 = this.longOpts.keySet().iterator();
    
        while(var3.hasNext()) {
          String longOpt = (String)var3.next();
          /******************************************************/
          /* longOpt = "multiply"                               */
          /* opt = "multi"                                      */
          /******************************************************/
          if (longOpt.startsWith(opt)) {
            matchingOpts.add(longOpt);
          }
          /******************************************************/
        }
    
        return matchingOpts;
      }
    }
    

    As you can see in the highlighted block, if a short option isn't matched the library searches for the first long option that partially matches the entered option. It uses startsWith, and since "multiply".startsWith("multi") is true it defaults to option --multiply.