why am i not able to work with the doGet()? : while i was learning servlet i used the method doGet() and i was using Get request method ,the HTTP Status 500 error showed up ,but while using doPost()  and post request was working perfectly fine.why am i not able to work with the doGet().

HTTP Status 500 – Internal Server Error
Type Exception Report

Message null

Description The server encountered an unexpected condition that prevented it from fulfilling the request.

Exception

    java.lang.NumberFormatException: null
	java.lang.Integer.parseInt(Unknown Source)
	java.lang.Integer.parseInt(Unknown Source)
	com.kiran.AddServlet.doGet(AddServlet.java:12)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
Note The full stack trace of the root cause is available in the server logs.

Apache Tomcat/9.0.27