DB : Oracle runInstaller failed with no protocol specified

Error:

[oracle@localhost database]$ ./runInstaller
Starting Oracle Universal Installer...

Checking Temp space: must be greater than 80 MB. Actual 7440 MB Passed
Checking swap space: must be greater than 150 MB. Actual 2527 MB Passed
Checking monitor: must be configured to display at least 256 colors
>>> Could not execute auto check for display colors using command /usr/bin/xdpyinfo. Check if the DISPLAY variable is set. Failed <<<<

Some requirement checks failed. You must fulfill these requirements before

continuing with the installation,

Continue? (y/n) [n] y

Ignoring required pre-requisite failures. Continuing...
Preparing to launch Oracle Universal Installer from /tmp/OraInstall2012-05-12_01-26-43PM. Please wait ...[oracle@localhost database]$ No protocol specified
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:164)
at java.awt.Toolkit$2.run(Toolkit.java:821)
at java.security.AccessController.doPrivileged(Native Method)
at java.awt.Toolkit.getDefaultToolkit(Toolkit.java:804)
at com.jgoodies.looks.LookUtils.isLowResolution(Unknown Source)
at com.jgoodies.looks.LookUtils.<clinit>(Unknown Source)
at com.jgoodies.looks.plastic.PlasticLookAndFeel.<clinit>(PlasticLookAndFeel.java:122)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:242)
at javax.swing.SwingUtilities.loadSystemClass(SwingUtilities.java:1783)
at javax.swing.UIManager.setLookAndFeel(UIManager.java:480)
at oracle.install.commons.util.Application.startup(Application.java:758)
at oracle.install.commons.flow.FlowApplication.startup(FlowApplication.java:164)
at oracle.install.commons.flow.FlowApplication.startup(FlowApplication.java:181)
at oracle.install.commons.base.driver.common.Installer.startup(Installer.java:265)
at oracle.install.ivw.db.driver.DBInstaller.startup(DBInstaller.java:114)
at oracle.install.ivw.db.driver.DBInstaller.main(DBInstaller.java:132)

Solution:
Check the DISPLAY variable is set
Give xhost + in the VNC session as root user and retry the installation