How to create an object with data in Java

Question

I am writing a function that will create an object with data. So far I get objects with data but individually not as a collection. I would like to return an object with all designated data as one Student object, not just one input for every object. I tried to add objList.add(obj) out of the for loop too and outputs all null. Here is the code

class Student{  
   int id;     
   String name;    
   int age;         
public Student(int id, String name, int age) {  
        this.id = id;    
        this.name = name;         
        this.age = age;     
   } 
} 

public static List<Object> createObject(Student st, List<Map<String, String>> csvStudentData) {
    List<Object> objList = new ArrayList<>();
    Object obj = null;

    for(Map<String, String> studentData: csvStudentData) { 
       for (Map.Entry<String, String> entry = studentData.entrySet())  {
           String key = entry.getKey();
           String val = entry.getValue();
           obj = insertObjectData(st.getClass(), key, value);
           objList.add(obj);
       }
    }
    return objList;
}

Answer 1

You modify the method's body by the following:

public static List<Object> createObject(Student st, List<Map<String, String>> csvStudentData) {
    List<Student> objList = new ArrayList<>();
    for(Map<String, String> studentData: csvStudentData) { 
       Student student = new Student();
       for (Map.Entry<String, String> entry = studentData.entrySet())  {
           String key = entry.getKey();
           String val = entry.getValue();
           Field  field = Student.class.getDeclaredField(key);
           student.set(field, value);
       }
        objList.add(student);
    }
    return objList;
}

you also add a default constructor in the class Student

Answer 2

You can do it in java-8 stream

 List<Object> objList = csvStudentData.stream() 
              .flatMap(map->map.entrySet()
                               .stream()
                               .map(entry->insertObjectData(st.getClass(), entry.getKey(), entry.getValue())))
              .collect(Collectors.toList());