Exception in thread "main" java.lang.InternalError: Can't connect to X11 window server

Getting DISPLAY error while Oracle EBS R12 installation or running script which require GUI

[applmgr@test$ sh bsu.sh
No protocol specified
Exception in thread "main" java.lang.InternalError: Can't connect to X11 window server using ':0.0' as the value of the DISPLAY variable.
    at sun.awt.X11GraphicsEnvironment.initDisplay(Native Method)
    at sun.awt.X11GraphicsEnvironment.access$200(X11GraphicsEnvironment.java:65)
    at sun.awt.X11GraphicsEnvironment$1.run(X11GraphicsEnvironment.java:110)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.awt.X11GraphicsEnvironment.<clinit>(X11GraphicsEnvironment.java:74)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:190)
    at java.awt.GraphicsEnvironment.createGE(GraphicsEnvironment.java:102)
    at java.awt.GraphicsEnvironment.getLocalGraphicsEnvironment(GraphicsEnvironment.java:81)
    at sun.swing.SwingUtilities2.isLocalDisplay(SwingUtilities2.java:1457)
    at javax.swing.plaf.metal.MetalLookAndFeel.initComponentDefaults(MetalLookAndFeel.java:1556)
    at javax.swing.plaf.basic.BasicLookAndFeel.getDefaults(BasicLookAndFeel.java:148)
    at javax.swing.plaf.metal.MetalLookAndFeel.getDefaults(MetalLookAndFeel.java:1592)
    at javax.swing.UIManager.setLookAndFeel(UIManager.java:536)
    at javax.swing.UIManager.setLookAndFeel(UIManager.java:576)
    at javax.swing.UIManager.initializeDefaultLAF(UIManager.java:1345)
    at javax.swing.UIManager.initialize(UIManager.java:1455)
    at javax.swing.UIManager.maybeInitialize(UIManager.java:1422)
    at javax.swing.UIManager.getDefaults(UIManager.java:656)
    at javax.swing.UIManager.put(UIManager.java:985)
    at com.bea.plateng.common.ui.gui.GUIHelper.initPLAF(GUIHelper.java:69)
    at com.bea.plateng.patch.gui.PatchGUIHelper.startGui(PatchGUIHelper.java:90)
    at com.bea.plateng.patch.Patch.main(Patch.java:338)


Findings: From root user I am able to open the GUI

Solution:
To open up your display for all users from all hosts as your normal user you can do this with :
Login from root user and run xhost +
Now, retest the issue.