Dear Tomal,
Welcome to Programming world!
First of all, don't be confused to see different technologies like Spring, Hibernate, GWT, Android etc. And be focus what do you want to develop.
If you like to develop Web applicaton then you have many options under Java/PHP/Python/Ruby etc. You can develop the web application Responsive so that the website fits in every device (mobile, desktop, tablet).
If you like to develop native Mobile application, then you have several options, like Android SDK, iOS SDK, Windows Phone SDK. Just pick what you like and develop your app. You can also develop your mobile app with a cross platform mobile sdk, like PhoneGap, Titanium, Xamarin etc.
Or, you may want to develop a Desktop based application. You can do this with Java/C#/Python etc.
Or, you can develop J2ME (java supported mobile platform) based mobile app, that will run only J2ME supported devices.
So, at first you decide what do you like to develop and what will be the platform (mobile, desktop, web), then share with us, we must help you to choose the right technology/tool for you.
Thanks!