Eclipse: Set project compiler compliance settings to 1.5 Set project JRE build path entry to 'J2SE-1.5'

Problem:
Set project compiler compliance settings to 1.5
Set project JRE build path entry to 'J2SE-1.5'

Cause:
Project compiler compliance is set to lower than 1.5.

Solution:

Goto Project Properties -> Java Compiler,  you will see JDK Compliance in the right panel,  Right beneath it:

uncheck "Use compliance from execution environment 'CDC-1.0/Foundation-1.0' on the 'Java Build Path'", then choose proper Compiler compliance level: