Commonly used packages in java
java.lang package is introduced by the system by default
API: Application Program Interface, application programming interface
In layman’s terms, it is a set of class libraries provided by the system
three of java Version
JSE: java standard version contains the core API of java
JEE: Java Enterprise Edition, which adds javaWEB API on the basis of the standard version
JME: java streamlined version, mainly used for program development of mobile devices