JavaGeneralFaq

How do I see/set up my project build-time classpath?

Right click the project, select properties, go to Build Path.

How do I see/set up my runtime classpath?

By default, the runtime classpath will be the same as the build path. However, it is possible to change the runtime classpath by defining a Launch Configuration from the Run/Debug menus.

What is a source/Build Output folder?

A source folder contains file resources within your project that participate in the build. Generally, (for JDT) these are .java files, however anything can be in a source folder. Files that are not recognized as a Compilation Unit (e.g. .java files), but exist in a source folder get copied to the build output folder. If you have .properties or XML files in a source folder, they will be copied to the build output folder (usually "bin" or "build")

Why do files I put in the build directory keep getting erased?

The build directory is owned by the compiler. It can be erased at anytime. If you want files that are not compiled .java files (i.e. the .class for the compiled files) in the build directory, place them in the source folder instead. The compiler will copy any files found under the source folder that are not .java files over to the build directory automatically. These are typically resources like .properties files.

How do I get .class files into the build?

Create a folder in your project. Then put all of your class files in their appropriate package directories under this folder. Then bring up the Java Build Path from the properties for the project, go to the "Libraries" page, and click on the "Add Class Folder..." button. Select the folder you just created.

This will put this class folder onto the class path. It won't actually copy these files to the bin directory, but when you run the application through Eclipse, this folder will be added to the classpath.

How do I keep certain types of files in a source folder from being compiled or copied to the build output folder?

Modify the preference:
Window->Preferences->Java->Compiler->Other

If you are using an old build, this preference was previously located:
Preferences->Java->Builder

How can I put files on my classpath (e.g. .properties files) without putting them in a source folder?

Put them in a class folder (Java Build Path->Libraries->Advanced) or create a JAR that contains these files.

I have attached the sources to my library, but eclipse does not show the source?

Make sure your class files contain enough debug information. There are at least 3 kinds, the line number, the source file information, and the local variable table. The javac standard is to include line numbers and source info. Some libraries do not contain any debug information. The jdk does not contain the local variable, and the jre only the line numbers.

How do I set the default Java environment used by new projects?

Window / Preferences / Java / Installed JREs. If the JRE/JDK you want is already in the list, just click its checkbox (which is really a radio button). If not, click Add and locate the outermost install folder of the JRE/SDK, e.g.,

Last Modified 10/2/06 12:10 PM

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