The Eclipse UI does not yet acknowledge the existence of Java 8. If you wish to use Java 8 features, manually configure it by entering these lines in
<project>/.settings/org.eclipse.jdt.core.prefs:
org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.8
org.eclipse.jdt.core.compiler.compliance=1.8
org.eclipse.jdt.core.compiler.source=1.8