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Frequently Asked Questions for JDT.

JDT Users

Other FAQ collections

You may find your answer in one the following FAQ collection

How to disable the navigation bar or the mini package explorer located above the Java editor?

The navigation bar is called the Breadcrumb. To disable the breadcrumb, click Toggle Java Editor Breadcrumb in the main toolbar. Since 3.7, you can also choose Hide Breadcrumb from the context menu of a breadcrumb item. More details on the Java editor breadcrumb can be found in Eclipse help.

Can I use JDT outside Eclipse to compile Java code?

Yes, the batch compiler can be invoked from command line or via the ant javac adapter. More details can be found in Java development user guide.

How can I disable auto-indentation in the Java editor?

You can disable smart insert mode (Edit > Smart Insert Mode), alternatively you can also configure the Smart Insert Mode (Windows > Preferences > Java > Editor > Typing).

Can I enable code completion to be activated as I type like how it works in Visual Studio?

Go to Preferences > Java > Editor > Content Assist and paste "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz." (note the dot after z) into the "Auto activation triggers for Java:" field.

Why is Content Assist displaying an empty proposal window?

Check your default proposal generators by navigating to:

Window > Preferences... > Java > Editor > Content Assist > Advanced

Ensure the top-most table (defining the default content assist list) has your desired proposal generators. You'll likely want "Java Proposals"

Code completion inserts meaningless names for method parameters - arg0, arg1. What is the problem?

The argument names are fetched from the source or javadoc and if Eclipse cannot find them then it can only suggest arg0, arg1, etc. To solve the problem you can

  • Use a JDK, the sources are bundled with a JDK but not with a JRE (see also IRC FAQ ).
  • Another solution is to have the Javadoc installed locally. Eclipse can also fetch it from the web but this can timeout for slow connections in which case you get arg0, arg1, etc.
  • You can also configure Eclipse to insert the best guessed names, see Windows > Preferences > Java > Editor > Content Assist, select 'Insert best guessed names'.

Why are some files not getting copied into the output folder?

The Java builder builds the java files in the source folders and copies the rest of un-filtered files. One can modify the filtered files settings at:

 Window > Preferences... > Java > Compiler > Building > Output folder

JDT Extenders

Other FAQ collection

You may find your answer in the Java Development Tool API section of The Official Eclipse FAQs.

Can I use JDT outside Eclipse to manipulate Java code?

JDT Core has no dependency on UI side, however it requires a runtime-workbench. Hence you can use it in an Eclipse headless application or include all the dependent jar files in the class path of your application. (You will have to use ASTParser.setSource() and ASTParser.setEnvironment() to be able to parse non Eclipse Java projects.)

If your question is not answered above

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