如何在命令行参数中使用indexOf（）？

Question

How do I do to check if the following command line arguments - inventory make=Honda desc by_count total - have make= ?

I have created String[] savedArgs so I pass all the arguments to this array, but there is no indexOf() for arrays so I`ma little lost now...

I want to be able to look for make= in the command line arguments so I can use the appropriate method to show a list according to the car maker. All I could do is use the contains() to look for exact matches (Eg: make=Honda or make=BMW ) but this way I would repeat the same code many times and I believe that`s bad design.

Thanks in advance

Answer 1

If you want to handle input arguments yourself, you could check if each argument contains the substring of your argument name ('make=') and then split the string:

String make = "";
for (String arg : savedArgs) {
    if (arg.contains("make=")) {
        make = arg.split("make=")[1];
    }
}

Repeat for each argument as necessary.

A better solution might be to use Apache Commons CLI .

Answer 2

There isn't a built-in indexOf or similar method that would work out-of-the-box for what you want. One option is something like:

    final String makeArgPrefix = "make=";
    Optional<String> makeArg = Stream.of(args)
            .filter(arg -> arg.startsWith(makeArgPrefix))
            .findAny();
    makeArg.ifPresent(arg -> System.out.println(arg.substring(makeArgPrefix.length())));

This requires Java 8 since I am using streams. With make=Honda in the command line arguments this prints

Honda

It doesn't take into account that more than one command line argument could begin with name= . It could be refined depending on your exact requirements.

Allow me to add that standard interpretation of command line arguments processes them all from left to right (a sensible thing to do if you don't want to ignore some). Something like

for (String arg : args) {
    if (arg.equals("desc") {
        ascending = false;
    } else if (arg.startsWith(makeArgPrefix) {
        make = arg.substring(makeArgPrefix.length());
    } else if // and so on

}

Of course, do it the way that fits best to your particular situation.