CODEWITHSUNDEEP
javareflection
Paresh Jaiswal
Paresh Jaiswal

Reputation: 111

Getting the super class field using subclass using reflection

Basically, my requirement is to get the superclass object by using reflection so that i can get the field name and its value.

so, I have a class as 

Class Emp {
  private firstName;
  priavte lastName;
}

Class Dept extend Emp {
  private dpFirstName;
  priavte dpLastName;
}

and now am using

emp.getClass.getSuperClass

which give me the java.lang.Class type of the Dept class Now when i try to access the field by using the following code.

Class<?> fields = emp.getClass.getSuperClass;
for (Field field : fields.getDeclaredFields()) {
  field.setAccessible(true);             
  System.out.println(field.get(emp.getClass.getSuperClass));
}

It throws me exception as

Can not set java.lang.String field com.Dept.dpFirstName to java.lang.Class

can anyone help me how can I convert it into an object and so that I can access the filed

Upvotes: 0

Views: 881

Answers (3)

second
second

Reputation: 4259

Assuming that the valid version of your code looks like that:

class Emp {
    private String firstName;
    private String lastName;
}

class Dept extends Emp {
    private String dpFirstName;
    private String dpLastName;
}

Edit: Foget about the cast, works without it.

Class<?> fields = emp.getClass().getSuperclass();

for (Field field : fields.getDeclaredFields()) {
  field.setAccessible(true);             
  System.out.println(field.getName() + "\t" + field.get(emp));
}

Upvotes: 0

Oleg Cherednik
Oleg Cherednik

Reputation: 18255

Your problem is that you get superclass for Emp but not Dept.

Emp emp = new Emp();
Dept dept = new Dept();

Class<?> cls = emp.getClass().getSuperclass(); // it is Class<Object>
Class<?> cls = dept.getClass().getSuperclass(); // it is Class<Emp>

So, you can use the following snippet as a correct example:

class Emp {
    private String firstName = "first_name";
    private String lastName = "last_name";
}

class Dept extends Emp {
    private String dpFirstName = "dp_first_name";
    private String dpLastName = "dp_last_name";
}

public static void getSuperClassFields(Dept dept) throws IllegalAccessException {
    Class<?> cls = dept.getClass().getSuperclass();

    for (Field field : cls.getDeclaredFields()) {
        field.setAccessible(true);
        System.out.println(field.getName() + " = " + field.get(dept));
    }
}

public static void main(String[] args) throws IllegalAccessException {
    getSuperClassFields(new Dept());
    // in console you can see
    // firstName = first_name
    // lastName = last_name
}

Upvotes: 1

Manjeet Brar
Manjeet Brar

Reputation: 943

public class Emp {

    private String firstName;
    private String lastName;
}

public class Dep extends Emp{

    private String dpFirstName;
    private String dpLastName;
}

public class Main {

    public static void main(String[] args) throws Exception {
        Dep d = new Dep();

        Class<?> c = d.getClass().getSuperclass();

        for (Field field : c.getDeclaredFields()) {
            field.setAccessible(true);
            if(field.getName().equals("firstName")){
                field.set(d, "First Name");
            }
            if(field.getName().equals("lastName")){
                field.set(d, "Last Name");
            }
            System.out.println(field.getName() + "\t" + field.get(d));

        }

    }
}

Upvotes: 1

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