find fields of type String, Boolean, Integer using reflection

Question

Is there a way to find fields in a class that are of the Type

    java.lang.Character.TYPE
    java.lang.Byte.TYPE
    java.lang.Short.TYPE
    java.lang.Integer.TYPE
    java.lang.Long.TYPE
    java.lang.Float.TYPE
    java.lang.Double.TYPE

there is a isPrimitive method for char, byte, short etc.

Couldn't you use Field#getType()? – RoflcoptrException Feb 28 '11 at 22:14 — RoflcoptrException, Feb 28 '11 at 22:14
Entire question has been mis-stated, see below. – user207421 Mar 01 '11 at 22:20 — user207421, Mar 01 '11 at 22:20

Matt Ball · Answer 1 · 2011-02-28T22:29:57.330

You can start with Class#getDeclaredFields() to get an array of the fields in your class. Then, iterate over each Field in the array and filter as needed.

Something like this:

public static List<Field> getPrimitiveFields(Class<?> clazz)
{
    List<Field> toReturn = new ArrayList<Field>();

    Field[] allFields = clazz.getDeclaredFields();

    for (Field f : allFields)
    {
        Class<?> type = f.getType();
        if (type.isPrimitive())
        {
            toReturn.add(f);
        }
    }

    return toReturn;
}

More info:

Field#getType()
Class#isPrimitive() (though it sounds like you already know about this one)

Edit

It might be worth clarifying that the types java.lang.Character.TYPE, etc., are the same thing as the class literals. That is,

java.lang.Character.TYPE == char.class
java.lang.Byte.TYPE == byte.class
java.lang.Short.TYPE == short.class
java.lang.Integer.TYPE == int.class
java.lang.Long.TYPE == long.class
java.lang.Float.TYPE == float.class
java.lang.Double.TYPE == double.class

score 1 · Accepted Answer · answered Mar 01 '11 at 15:16

1

I was looking for one method that would return true for wrapper types. Springs ClassUtils provides one such method

ClassUtils.isPrimitiveOrWrapper(field.getType())

returns true for all of the above that I requested, except String

answered Mar 01 '11 at 15:16

user373201

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Then your entire question is incorrectly stated. Integer.TYPE is 'int', not a 'wrapper class'. – user207421 Mar 01 '11 at 22:13

score 0 · Answer 3 · answered Mar 01 '11 at 00:18

0

Those types are all primitives, so use isPrimitive().

answered Mar 01 '11 at 00:18

user207421

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isPrimitive() on java.lang.Integer returns false not true – user373201 Mar 01 '11 at 15:14
3

Irrelevant. Integer.TYPE == int.class as pointed out by Matt Ball. 'int' is a primitive, and isPrimitive() will return 'true' for it. Integer.TYPE is *not* Integer.class. – user207421 Mar 01 '11 at 22:09

find fields of type String, Boolean, Integer using reflection

3 Answers3

Something like this:

More info:

Edit

Linked

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