如何检查输入参数的值是否为空

Question

I'll be receiving an HTTP URL with three input parameters. In that one of the parameter is a string and other two of integer values.

I want to check whether all three request parameters are present or not. Also, I need to check all the input parameters is null or not..

Example - http url:

http: //....../a=123456&b=12345678&c=y

Answer 1

String a = request.getParameter("a");
String b = request.getParameter("b");
String c = request.getParameter("c");

if(a != null && !a.isEmpty()) {
    //Do something with a.
}

if(b != null && !b.isEmpty()) {
    //Do something with b.
}

if(c != null && !c.isEmpty()) {
    //Do something with c.
}

If the request parameter is not present it will be null. If it is present but has no data set, it will be an empty string.