The Servlet engine will share the instance of you servlet across multiple users. Since, objdata1 is an instance variable, it follows that objdata1 will be shared among users. You need to rework your methods so that objdata1 is not an instance variable. You should probably make objdata1 a local variable. Some thing like this
We're pleased to have you here with us on the Ranch, but there are a few rules that need to be followed, and one is that proper names are required. Please take a look at the JavaRanch Naming Policy and adjust your display name to match it.
In particular, your display name must be a first and a last name separated by a space character, and must not be obviously fictitious.