instance of generic type in Java

Question

I want to write a little "factory" for a number of methods that has the same set of arguments. Here is my code so far (it is so wrong that event the IDE won't let it it pass)

 public <T> T callServer(String param1, String param2, String param3){
    if (T instanceof Type1 ){
        return (T) callFunctionServerType1(param1,  param2, param3);
    }
    else if (T instanceof Type2)
        return  (T) callFunctionServerType2(param1,  param2, param3);
    return null;
}

The IDE says that and expression is expected and underlines each T thas is just after the if statement (if (T ...) ). Can you help me to solve this problem.

Answer 1

You can pass needed class of T as additional parameter

public <T> T callServer(String param1, String param2, String param3, Class<? extends T> returnClass)
{
  if (Type1.class.isAssignableFrom(returnClass)) {
     ...