Can't connect to X11 window server and bash: setenv: command not found

1.[oracle@cdcjpXX bin]$ ./rcu
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$100(X11GraphicsEnvironment.java:52)
at sun.awt.X11GraphicsEnvironment$1.run(X11GraphicsEnvironment.java:155)
at java.security.AccessController.doPrivileged(Native Method)
at sun.awt.X11GraphicsEnvironment.<clinit>(X11GraphicsEnvironment.java:131)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:169)
at java.awt.GraphicsEnvironment.getLocalGraphicsEnvironment(GraphicsEnvironment.java:68)
at sun.awt.X11.XToolkit.<clinit>(XToolkit.java:89)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:169)
at java.awt.Toolkit$2.run(Toolkit.java:834)
at java.security.AccessController.doPrivileged(Native Method)
at java.awt.Toolkit.getDefaultToolkit(Toolkit.java:826)
at com.jgoodies.looks.LookUtils.isLowResolution(LookUtils.java:484)
at com.jgoodies.looks.LookUtils.<clinit>(LookUtils.java:249)
at com.jgoodies.looks.plastic.PlasticLookAndFeel.<clinit>(PlasticLookAndFeel.java:135)
at oracle.sysman.assistants.rcu.ui.InteractiveRCUModel.<init>(InteractiveRCUModel.java:117)
at oracle.sysman.assistants.rcu.Rcu.execute(Rcu.java:307)
at oracle.sysman.assistants.rcu.Rcu.main(Rcu.java:363)

Pls try setting the display variable to:
export DISPLAY=localhost:0.0, but no luck.
try again:
export DISPLAY=localhost:1.0

and also try following:
[root@ds26 rick]# xhost + localhost
xhost: unable to open display ""
The code worked for me.

2.bash: setenv: command not found
[root@cdcjpXX]# more /etc/shells
/bin/sh
/bin/bash
/sbin/nologin
/bin/tcsh
/bin/csh
/bin/ksh
/usr/bin/ksh
/usr/bin/pdksh

[root@cdcjpXX]echo $SHELL
/bin/bash
[root@cdcjpXX /bin]#tcsh
[root@cdcjpXX /bin]# setenv ORACLE_SID XE

The code worked.