检查 class 名称不应包含特定文本

Question

I have a class the following class University.

public class University {
private List<Student> Students = null;
private List<Departments> department;
private CanteenName canteenName;
private LibraryName libraryName;
}

I have to write a logic where i need to check each variables in this class and if any variable name like in this case(Canteen Name ,Library Name ) contains a text ' Name ' in it, it should check if it is null or not, other variable it should ignore.

I thought of doing a null check using the getter property, but is there any dynamic way as the class contain any number of variable like (Canteen Name ).

Answer 1

You can achieve this by using reflection:

public static void checkObjectFieldForNull(Object obj, String... fieldNames) throws Exception {
   if (obj == null) return;
   //get all the fields in the object
   for (Field f : obj.getClass().getDeclaredFields()) {
     f.setAccessible(true); //set the fields to be accessible
     for (String str : fieldNames) {
        //loop through the fieldNames and see if they are null
        if (f.getName().toLowerCase().contains(str.toLowerCase())) {
          Obj val = f.get(obj);
          //throw an exception if any of the required fields are null
          if (val == null) throw new Exception(f.getName() + " cannot be null");
        }   
     }
   }
}

Then in your program:

public static void main(String[] args) {
   University u = new University();
   checkObjectFieldForNull(u, "name");
}