Problem on installing Oracle product in Linux through GUI

When installing Oracle Database/JDE/Server Manager in Linux GUI mode using Oracle account, the following error occur.

To rectify the issue:

1. login to the Linux console with root account
2. type in DISPLAY=:0.0
3. type in export DISPLAY
4. type in xhost +
5. login to oracle account su - oracle
6. type in DISPLAY=:0.0
7. type in export DISPLAY
8. type xclock and see if the previous said error still appears or not. 
9. if a clock appears that means configuration is done. 
10. You may proceed to install using oracle account in Linux.