do know a bit on how to animate a object in keyframe, so can i animate the object in keyframe, and save as .3ds then import to java?
Simple time/keyframe based animation is possible with .3ds and it's usually being loaded by Kevin's 3dsloader to a Xith3d scenegraph.
Please have a look at his 3ds-loader: http://www.newdawnsoftware.com/resources/xith3d/
. The zip archive contains a Character.3ds which is animated.
However complex models are not always loadable in a clean way. So it depends on your model and which tool exported it, etc.
There are some threads on the Xith3d forum: http://www.java-gaming.org/cgi-bin/JGNetForums/YaBB.cgi?board=xith3d
so that i don't need to use the skeleton method to animate the object...since keyframe is much more easy is it??
Unfortunately I'm no expert with 3d or 3d animations at all, I am just a newbie Xith3d user... Skeletons and bones are not yet possible to load anyway with Xith3d, but in the future.
The problem im facing now is how to import the object to java? if i can manage to display the object
Well, you set up your scenegraph in Xith3d, which is pretty easy. Please have a look at the mentioned forum and some threads there, or ask the question over there.
Then you use the 3dsloader for example, to load a new scenegraph node and add that to your root scene graph.
Depending on what you want to do it needs some studying of the API and/or tutorials, but basically it's really simple. Well even I managed to use it. :-)
Lastly, use a high level 3d API for Java (for example Xith3d, or SUN's froozen J3D) is it same as the normal java3d only is a class???
I don't know Java3d in practice, I've just taken a look at its API and tutorials. So no comment on the quality of Java3d's loaders and so on. I am using Xith3d currently and it looks very similar to Java3d, which is nice.
Java3d you've to install additionally to a Java JRE/SDK and it's available for Win32 and Mac.
Xith3d uses the new JOGL API as its OpenGL binding (and in future you can choose to use LWJGL as its OpenGL binding). So next to your app.jar and xith.jar you've to use the native jogl.dll/jogl.so/blabla which runs on Mac, Linux, Solaris, Win32 and several more (please see Jogl forum for details).
In contrast to Java3d you can bundle a Xith application very nicley via Webstart so it's matter of a click to start it on a JRE'ed PC.
Please take a look at a small example I bundled for a test in this thread: http://www.java-gaming.org/cgi-bin/JGNetForums/YaBB.cgi?board=xith3d;action=display;num=1078132539