New to Java

Hi,

I have "quantity" variable as an Integer datatype , which should not allow "0" (zero) or "any negative values" (-1). Is there any simple predefined function in java to check this and throw a validation message if quantity is "0" or "-ve"? I should not use Javascript.
Similarly if i add a value "<ragav555>" for "name" field it is added properly but in the update page the value "<ragav555>" is not displayed, this is happening only for "<ragav555>" , for "<555>" it is working fine. The name field is of varchar.

Thanks