By mistake i removed the jre default from eclipse java project instead of updating jre with jdk as beow
Here is the complete sequence in Eclipse Luna:
Right click your project > properties.
Select “Java Build Path” on left, then “JRE System Library”, click Edit…
Select "Workspace Default JRE"
Click "Installed JREs"
If you see JRE you want in the list select it (selecting a JDK is OK too)
how to add jdk 1.8