How do I specify an old JDK compliance in an Eclipse project?

Question

I have a project that I need to be compatible with only up to JDK 1.4. However, I don't have a JDK 1.4 installed on my system (Mac). I get the following warning in Eclipse:

Build path specifies execution environment J2SE-1.4. There are no JREs installed in the workspace that are strictly compatible with this environment.

I have a JDK 8 installed that is compatible but Eclipse is not recognizing it. I don't want anything over 1.4 to enter this project. How do I go about configuring this?

Answer 1

The project is probably configured to use JDK 1.4.

Since you don't have that one installed, you need to remove it and add the 1.8 you actually have.

• Right click the project and select "Build Path" -> "Configure Build Path"
• In the "Java Build Path" option, remove the "JRE 1.4"
• Go to "Libraries" -> "Add Library" and add the JRE 1.8

Then you can configure the source compatibility to use 1.4 so that new features cannot be used.

• "Build Path" -> "Configure Build Path"
• Select "Java Compiler"
• Configure "Source Compatibility" to be "1.4"