JDK 1.6 on Solaris

the issue is with the settings of your PATH
run which java and you will likely see:
/usr/bin/java or /usr/local/bin/java.

Depending on your shell, you may need to do export PATH=/usr/jdk/bin:$PATH.

removing the older version should depend on whether it is needed for system management.
pkginfo
Locate the Java Pacakage
pkginfo -i or -l packagename will provide info on the package.

NOTE: be very careful with removing packages. SUNWjava is merely used as an example for the java package name.
pkgrm SUNWjava.

NetBeans shows that it use 1.6, but I try to set -Xms on it and found 1.5
So, if I use Java only for NetBeans at the moment I can leave it as it is ?
Just advice how to put VM parameters in 1.6

I'm not sure what you are asking.

If you add the /usr/jdk/bin to the search path
sh/bash
export PATH=/usr/jdk/bin:$PATH
csh
setenv path=/usr/jdk/bin:$path

Will change the behavior, you could also do alias java="/usr/jdk/bin/java"

In /usr/jdk I have:
# cd /usr/jdk
# ls
instances      jdk1.5.0_20    latest
j2sdk1.4.2_22  jdk1.6.0_21    packages
#

apart of jdk I have also java and j2se in /usr
everything were installed with Solaris, this reason I ask how to clean it from unused old versions and leave one, new one

I would set JAVA_HOME to the one you want and then

export PATH=${JAVA_HOME}/bin:${PATH}

# JAVA_HOME=/usr/jdk/jdk1.6.0_21
# export PATH=${JAVA_HOME}/bin:${PATH}
PATH=/usr/jdk/jdk1.6.0_21/bin:/usr/sbin:/usr/bin: is not an identifier
#

# $JAVA_HOME
/usr/jdk/jdk1.6.0_21: cannot execute
# java -version
java version "1.6.0_21"
Java(TM) SE Runtime Environment (build 1.6.0_21-b06)
Java HotSpot(TM) Server VM (build 17.0-b16, mixed mode)

Ok, this is clear, but what to do with garbage?

You can try like:

# which java
this will show the path for current java, eg. /usr/bin/java, normally this is a symbolic link.

To cleanup old java, just remove this link.

Then, create a symbolic link to your new java command where ever is:

# ln -s {new java path} /usr/bin/java (example only, depend on "which java" command output).

# which java
/usr/jdk/jdk1.6.0_21/bin/java

so, now it's correct java and I can delete all old versions from jdk folder and leave only 1.6?
But what to do with folders java and j2se?

Yes, you can delete all old java pathes/directoies, if you sure not going to use. But don't remove any packages if you don't know.

Just for last confirmation before deleting:
I will leave in usr/jdk folder only two folders: 1.6 and packages and all other related to java delete, including folders java and j2se?

Should be ok, but if you can copy/backup to somewhere else before delete just in case.

you know that the best treatment for dandruff is a guilliotine :-)

Thank you for real practical help!
Please check another my question about Java VM