Observe

One of the main advantages of using IDE is that it makes life easy for a programmer.
For example,if I were to type a program which has a command to print a statement,one can observe that a window pops up as soon as "System." is typed. This window is as shown below.

This happens because the System class contains several class fields and methods and they cannot be instantiated. The facilities provided by the System class include standard input, standard output, and error output streams. By convention, this output stream is used to display information or messages that are intented to be attended by the user. "println" which is normally added at the terminal end belongs to the PrintStream. This class prints Java primitive values and object to a stream as text. Errors if present can be detected by calling the checkError() method. Additionally, this stream can be designated as "autoflush" when created so that any writes are automatically flushed to the underlying output sink when the current line is terminated. "println" just terminates the current line by inserting a line separator string(which does not mean \n).