Building without cleaning the output location

To build projects without cleaning the output location:

Select the Window > Preferences > Java > Compiler > Build Path page.
Then set the Scrub output folders on full build check box.

To build projects after cleaning the output location:

Select the Window > Preferences > Java > Compiler > Build Path page.
Then clear the Scrub output folders on full build check box.

To build a single project without cleaning the output location:

Select the project, and from its pop-up menu, select Properties.
In the Properties dialog, select the Java Compiler > Build Path page.
Then set the Scrub output folders on full build check box.

To build a single project after cleaning the output location:

Select the project, and from its pop-up menu, select Properties.
In the Properties dialog, select the Java Compiler > Build Path page.
Then clear the Scrub output folders on full build check box.

Java builder
Build class path

Building a Java program
Building manually
Viewing compilation errors and warnings
Working with build paths
Adding a JAR file to the build path
Adding a library folder to the build path
Viewing and editing a project's build path

Java Build path