I was tired of searching on google how to run iReport with java 8.
I did everything as said on the Internet,But I don't know why they weren't work for me.
Then I Change My Computer JDK Current Version form 1.8 to 1.7 Using Registry Editor.
Now it work fine.
To Change Current Version
Start => Type regedit (Press Enter) => HKEY_LOCAL_MACHINE => SOFTWARE => JavaSoft => Java Development Kit => Change Key Value of CurrentVersion From 1.8 to 1.7