Java is very important language.Being a Computer Science Student, I can tell you nowadays most of the technologies are demanding knowledge of Basics of Java. Like if you have to go for Android, Hadoop, Advance Java, etc, You need it.
Features of this book are:
Everything is given in a very easy language.
Balagurusamy is a reputed writer.
Examples and Programs are properly mentioned.
It is an easy book rather than reading Complete Reference for Java