Java Reflection - how to set value for the class which are extended from One and Two

Question

Goal :

set the value for a class fields as well the extended class fields

Example :

public class CreateRequisitionRO extends AbstractPortfolioSpecificRO {....}

i am able to set value for the CreateRequisitionRO but not able to set value for AbstractPortfolioSpecificRO which is being extended.

This is how i set the value :

public Object creatObjectWithDefaultValue(String className) throws IllegalArgumentException, IllegalAccessException, InstantiationException {
 Class<?> objectClass = null;
 Object clsObject =null;
 try {
 objectClass = Class.forName(className);
 clsObject = objectClass.newInstance();
 Field[] fields = objectClass.getDeclaredFields();
 for(Field f:fields){
 if(!f.isAccessible()){
 f.setAccessible(true);
 Class<?> type = f.getType();
 if(! Modifier.isFinal(f.getModifiers()) && type.equals(Integer.class)){
 f.set(clsObject, DefaultParamValuesEnum.INTEGER.getDefaultInt()); 
 } else if( !Modifier.isFinal(f.getModifiers()) && type.equals(java.math.BigDecimal.class)){
 f.set(clsObject, DefaultParamValuesEnum.BIGDECIMAL.getDdefaultBigDecimal()); 
 } else if(! Modifier.isFinal(f.getModifiers()) && type.equals(org.joda.time.LocalDate.class)){
 f.set(clsObject,DefaultParamValuesEnum.DATE.getDefaultDate()); 
 } else if(! Modifier.isFinal(f.getModifiers()) && type.equals(boolean.class)){
 f.set(clsObject, DefaultParamValuesEnum.BOOLEAN.getDefaultBoolean()); 
 } else if(! Modifier.isFinal(f.getModifiers()) && type.equals(java.lang.String.class)){
 f.set(clsObject, DefaultParamValuesEnum.STRING.getDefaultString()); 
 }
 else if(! Modifier.isFinal(f.getModifiers()) && type.equals(long.class)){
 f.set(clsObject,DefaultParamValuesEnum.LONGVALUE.getDefaultLong()); 
 }
 }
 }
 } catch (ClassNotFoundException e) {
 e.printStackTrace();
 }
 return clsObject;
 }

This is how i call the above method :

classObject.creatJSONObject("com.hexgen.ro.request.CreateRequisitionRO");

The above way sets value for all the fields available in CreateRequisitionRO not fields which are available in extended class.

How to set it?

• Sean Patrick Floyd: you should wrap this check around the other checks: if(! Modifier.isFinal(f.getModifiers())) instead of doing the same check over and over again

Answer 1

You can use clazz.getSuperclass() to retrieve the supertype of CreateRequisitionRO. Once you have a handle on the supertype AbstractPortfolioSpecificRO you can iterate its fields. I would recommend storing all of these fields in a List<Field>. Iterate through this list and set the fields based upon your conditional logic.

I have provided a quick example of how to perform this. In my example, Child extends Parent. The recursive getFields method returns a List<Field> that contains all of the fields for Child. I then iterate through the List<Field> setting the value for each one. Notice that I must switch the accessibility of private fields.

Child.Java

public class Child extends Parent {
 public String a;
 public String b;
 public static void main(String[] args) throws IllegalArgumentException, IllegalAccessException {
 Child child = new Child();
 List<Field> fields = getFields(child.getClass());
 for(Field f: fields){
 f.setAccessible(true);
 f.set(child, "Test");
 }
 for(Field fd: fields){
 System.out.println(fd.get(child));
 fd.setAccessible(false);
 }
 }
 public static List<Field> getFields(Class<?> clazz){
 List<Field> list = new ArrayList<Field>();
 list.addAll(Arrays.asList(clazz.getDeclaredFields()));
 if(clazz.getSuperclass() != null){
 list.addAll(getFields(clazz.getSuperclass()));
 }
 return list;
 }
}

Parent.java

public class Parent {
 private String x;
 public String y;
 protected String z;
}

• Java Questions: Thanks for the nice explanation +1. will do this and mark this as answer as this will help others too.
• Kevin Bowersox: @Anto Glad I could help. If you have any further questions let me know.
• Java Questions: Kevin i get only field name like the following userId when i use getSuperclass(). but i need to get like private java.lang.String com.hexgen.ro.request.CreateRequisitionRO.custodianN is it possible
• Kevin Bowersox: getDeclaredFields should pull the private fields also.
• Java Questions: let us continue this discussion in chat

Answer 2

You can get super class of your class using Class<SuperClass> superClazz = clazz.getSuperclass();

Once got, get the Field[] using superClazz.getFields() and use set method of Field

Answer 3

Use getSuperclass() method to obtain the class object of superclass. and then in the similar way get the fields of superclass.

Answer 4

obj.getClass().getSuperclass().getDeclaredFields();

you can use above function for achieving same ..

also check Access to private inherited fields via reflection in Java