How to get all field's title of object

I need to write a method. The meaning is to send any object(Entity etc) as parameter and get all fields names as return values. Something like that.

Example of method

public String getFieldsTitle(Object obj){

   return obj.getListOfFields();

}

Entity for example:

public class Human{
private String name;

private String fam;

private String patr;

}

Expectation value of method

[name,fam,patr]