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2. Using an Eclipse plugin for Maven (see Eclipse Integration, Eclipse Integration )
Use the first one if you're much more comfortable with using the command line for your Maven tasks, but would like to take advantage of Eclipse' features ( code complete, refactoring, etc ). Use the second one if you want Eclipse to handle all these things - creation to editing to execution.
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To do so, you must install an Eclipse plugin for maven, see Eclipse Integration, Eclipse Integration.
Debugging your Maven Project in Eclipse
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