fork download
copy 
  1. import java.lang.annotation.ElementType;
  2. import java.lang.annotation.Retention;
  3. import java.lang.annotation.RetentionPolicy;
  4. import java.lang.annotation.Target;
  5. import java.lang.reflect.Field;
  6.  
  7. // @UserPreference marks a field that should be exported.
  8. @Retention(RetentionPolicy.RUNTIME)
  9. @Target(ElementType.FIELD)
  10. @interface UserPreference {
  11. }
  12.  
  13. // @HasUserPreferences marks a field that should be recursively scanned.
  14. @Retention(RetentionPolicy.RUNTIME)
  15. @Target(ElementType.FIELD)
  16. @interface HasUserPreferences {
  17. }
  18.  
  19.  
  20. // Your example Login class, with added annotations.
  21. class Login {
  22.  
  23.     @UserPreference public String token;      // <= a preference
  24.     @UserPreference public String customerid; // <= a preference
  25.     @HasUserPreferences public Class1 class1; // <= contains preferences
  26.  
  27.     public class Class1 {
  28.         @HasUserPreferences public Class2 class2; // <= contains preferences
  29.         @UserPreference public String string1;    // <= a preference
  30.  
  31.         public class Class2 {
  32.                 public int int1; // <= not a preference
  33.                 @UserPreference public String string2; // <= a preference
  34.                 @UserPreference public String string3; // <= a preference
  35.         }
  36.     }
  37.  
  38.     // Construct example:
  39.     public Login () {
  40.         token = "token1";
  41.         customerid = "586969";
  42.         class1 = new Class1();
  43.         class1.string1 = "string1Value";
  44.         class1.class2 = class1.new Class2();
  45.         class1.class2.string2 = "string2Value";
  46.         class1.class2.string3 = "string3Value";
  47.     }
  48.  
  49. }
  50.  
  51.  
  52. public class Main {
  53.  
  54.     // Recursively print user preferences. 
  55.     // Fields tagged with @UserPreference are printed.    
  56.     // Fields tagged with @HasUserPreferences are recursively scanned.
  57.     static void printUserPreferences (Object obj) throws Exception {
  58.         for (Field field : obj.getClass().getDeclaredFields()) { 
  59.             // Is it a @UserPreference?
  60.             if (field.getAnnotation(UserPreference.class) != null) {
  61.                 String name = field.getName();
  62.                 Class<?> type = field.getType();
  63.                 Object value = field.get(obj);
  64.                 System.out.println(name + " - " + type + " - " + value);
  65.             }
  66.             // Is it tagged with @HasUserPreferences?
  67.             if (field.getAnnotation(HasUserPreferences.class) != null) {
  68.                 printUserPreferences(field.get(obj)); // <= note: no casts
  69.             }
  70.         }
  71.     }
  72.  
  73.     public static void main (String[] args) throws Exception {
  74.         printUserPreferences(new Login());
  75.     }
  76.  
  77. }
Success #stdin #stdout 0.11s 380352KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
token - class java.lang.String - token1
customerid - class java.lang.String - 586969
string2 - class java.lang.String - string2Value
string3 - class java.lang.String - string3Value
string1 - class java.lang.String - string1Value
https://ideone.com/brSAHU
language:
Java (HotSpot 12)
created:
10 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!