Java servlet null pointer exception

java.lang.NullPointerException 

at servlet.AddUser.doGet(AddUser.java:44)
at servlet.AddUser.doPost(AddUser.java:65)

Why does a pointer exception be reported here

Java-ee servlet
Feb.16,2022

interestings variable is empty, no corresponding parameter

is obtained.

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MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b32c56-2be3a.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b32c56-2be3a.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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