title: functional interfaces of java 8 in java 7
body: <p>are the functional interfaces of java 8 available somewhere (i.e. a jar) so I can use them in a Java 7 project? that way I could later on easier port the code to idiomatic java 8. if not, is that technically possible or do they make use of new features like default methods?</p>
  
  <p>yes, i meant the interfaces in java.util.function. since adding packages with the java prefix seems to be disallowed importing them from somewhere else is not an option.</p>