Setting field value to null with reflection

Question

I am setting a variable value to null, but having problem with it:

public class BestObject {
    private Timestamp deliveryDate;
    public void setDeliveryDate(Timestamp deliveryDate) {
         this.deliveryDate = deliveryDate;
    }
}

BeanUtils.setProperty(new BestObject(), "deliveryDate", null); // usually the values are not hardcoded, they come from configuration etc

This is the error:

org.apache.commons.beanutils.ConversionException: No value specified
    at org.apache.commons.beanutils.converters.SqlTimestampConverter.convert(SqlTimestampConverter.java:148)
    at org.apache.commons.beanutils.ConvertUtils.convert(ConvertUtils.java:379)
    at org.apache.commons.beanutils.BeanUtils.setProperty(BeanUtils.java:999)

Basically it is trying to set a java.sql.Timestamp value to null, but it is not working for some reason.

On the other hand, I am using reflection wrapper BeanUtils(http://commons.apache.org/proper/commons-beanutils/), maybe this is possible with plain reflection?

Your example is not compilable. Where does 'myObject' come from? Please edit your code so we can tell what's going on. (Show myObject's instantiation) — Rebecca Nelson, Oct 08 '13 at 13:23
@TFNelson sorry, myObject is the POJO, where deliveryDate is. I will try to edit to make it better. — Jaanus, Oct 08 '13 at 13:26

score 16 · Accepted Answer · answered Oct 09 '13 at 06:37

16

I managed to do it with standard reflection.

java.lang.reflect.Field prop = object.getClass().getDeclaredField("deliveryDate");
prop.setAccessible(true);
prop.set(object, null);

answered Oct 09 '13 at 06:37

Jaanus

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score 2 · Answer 2 · answered Sep 02 '15 at 18:29

2

It can be done by simple trick

Method setter;
setter.invoke(obj, (Object)null);

answered Sep 02 '15 at 18:29

Błażej

151
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7

score 1 · Answer 3 · answered Oct 08 '13 at 13:41

1

A similar complaint (and workaround) was posted in the bug tracker for BeanUtils. See https://issues.apache.org/jira/browse/BEANUTILS-387

answered Oct 08 '13 at 13:41

bstempi

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score 1 · Answer 4 · answered Nov 16 '18 at 07:08

1

Book book = new Book();
Class<?> c = book.getClass();
Field chap = c.getDeclaredField("chapters");
chap.setLong(book, 12)
System.out.println(chap.getLong(book));

[Oracle Offical Source] https://docs.oracle.com/javase/tutorial/reflect/member/fieldValues.html

answered Nov 16 '18 at 07:08

Oguzhan Cevik

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Very good exemple, that with that we can create a generic method for set in a field – Sham Fiorin Jul 04 '19 at 20:48

Setting field value to null with reflection

4 Answers4