Invoking Java main method with parameters from Eclipse

Question

During development (and for debugging) it is very useful to run a Java class' public static void main(String[] argv) method directly from inside Eclipse (using the Run As context menu).

Is there a similarily quick way to specify command line parameters for the run? What I do now is go to the "Run Dialog", click through the various settings to the tab where I can specify VM and program arguments and enter them there. Too many steps, plus I do not want to mix the more permanent runtime configuration settings with the one-off invokation parameters. What I want instead is to check a box somewhere (or have a separate menu item "Run as Java application with command line") and then be prompted for the commandline every time (with a nice history).

Answer 1

This answer is based on Eclipse 3.4, but should work in older versions of Eclipse.

When selecting Run As..., go into the run configurations.

On the Arguments tab of your Java run configuration, configure the variable ${string_prompt} to appear (you can click variables to get it, or copy that to set it directly).

Every time you use that run configuration (name it well so you have it for later), you will be prompted for the command line arguments.

Answer 2

Uri is wrong, there is a way to add parameters to main method in Eclipse directly, however the parameters won't be very flexible (some dynamic parameters are allowed). Here's what you need to do:

1. Run your class once as is.
2. Go to Run -> Run configurations...
3. From the lefthand list, select your class from the list under Java Application or by typing its name to filter box.
4. Select Arguments tab and write your arguments to Program arguments box. Just in case it isn't clear, they're whitespace-separated so "a b c" (without quotes) would mean you'd pass arguments a, b and c to your program.
5. Run your class again just like in step 1.

I do however recommend using JUnit/wrapper class just like Uri did say since that way you get a lot better control over the actual parameters than by doing this.

Answer 3

AFAIK there isn't a built-in mechanism in Eclipse for this.

The closest you can get is to create a wrapper that prompts you for these values and invokes the (hardcoded) main. You then get you execution history as long as you don't clear terminated processes. Two variations on this are either to use JUNit, or to use injection or parameter so that your wrapper always connects to the correct class for its main.

Answer 4

I'm not sure what your uses are, but I find it convenient that usually I use no more than several command line parameters, so each of those scenarios gets one run configuration, and I just pick the one I want from the Run History.

The feature you are suggesting seems a bit of an overkill, IMO.

Answer 5

Another idea:

Place all your parameters in a properties file (one parameter = one property in this file), then in your main method, load this file (using Properties.load(*fileInputStream*)). So if you want to modify one argument, you will just need to edit your args.properties file, and launch your application without more steps to do...

Of course, this is only for development purposes, but can be really helpfull if you have to change your arguments often...

Answer 6

If have spaces within your string argument, do the following:

Run > Run Configurations > Java Application > Arguments > Program arguments

1. Enclose your string argument with quotes
2. Separate each argument by space or new line