Print whole structure with single call (like JSON.stringify) in Java?

Question

How to print any class instance in Java? Similar to JSON.stringify() in Javascript. Not necessary JSON, any format of output will do.

public class User {
    pub         


        

Answer 1

There could be many ways to achieve what you need. Though i would be interested in why you need.

1. Override the toString() method.

   see: http://www.javapractices.com/topic/TopicAction.do?Id=55

2. If the generation algorithm gets too long, then consider a separate class say UserPrettyPrinter.

   public interface UserPrettyPrinter {
     string print(User);
   }
   
   public class PrintUserInJSON implements UserPrettyPrinter {
     string print(User user) {
       //implement the algo here
     }
   }
   

   you can also implement:

   public class PrintUserInXML implements UserPrettyPrinter {
     string print(User user) {
       //implement the algo here
     }
   }
   

3. Either in conjugation to number-2 or as a standalone class, you can write

   public class PrintObjectBasicAlgo {
     String print(Object obj) {
       /* i write pseudo code here. just ask if you cannot implement this
       this would help: http://docs.oracle.com/javase/tutorial/reflect/class/classMembers.html
   
       Class class = Obj.getClass();
   
       Filed[] allVariables = class.getAllFieldsByReflection();
   
       ArrayList keys = new ArrayList;
       ArrayList values = new ArrayList;
   
       for(Field field : allVariables) {
           Object value = reflectionGetValueOfField( field, obj );
           keys.add( field.getName());
           values.add(value.toString());
       }
   
       now that you have the keys and values, you can generate a string in anyway you like
   
       */
     }
   }
   

4. You may see Visitor Pattern. it might be helpful.