Using readLine MUST has to keep below detail in mind.

readLine Returns:

A String containing the contents of the line, not including any line-termination characters, or null if the end of the stream has been reached.

For example:

Before:

AAA
BBB
CCC

After:

AAABBBCCC

Reference:https://docs.oracle.com/javase/7/docs/api/java/io/BufferedReader.html