@Group Ordering fields of DataValueClasses

The @Group annotation can be added to the interfaces you pass to :

DataValueClasses.newDirectReference(<interface>)
DataValueClasses.newDirectInstance(<interface>)

The above methods create classes that implement the getter/setter methods of your interface. By default when these classes are serialized, their fields will be ordered by field size ( smallest first ), however sometimes, especially when you add new fields, you may not want new small fields to be serialize towards the top, You may wish to preserve the existing order of your fields, you can do this by using the @Group annotation to each method. The serialization order of the fields are determined by adding @Group to the set() method, If you wish you can have a number of different methods with the same value in @Group(), Methods with the same value continue to be ordered by size ( smallest first).

see test below

import net.openhft.lang.io.ByteBufferBytes;
import net.openhft.lang.io.IByteBufferBytes;
import net.openhft.lang.model.Byteable;
import net.openhft.lang.model.DataValueClasses;
import net.openhft.lang.model.constraints.Group;
import net.openhft.lang.model.constraints.MaxSize;
import org.junit.Assert;
import org.junit.Test;

import java.nio.ByteBuffer;

/**
 * Rob Austin
 */
public class GroupTest {

    @Test
    public void test() {

        IByteBufferBytes byteBufferBytes = ByteBufferBytes.wrap(ByteBuffer.allocate(1024));

        {
            BaseInterface baseInterface = DataValueClasses.newDirectInstance(BaseInterface.class);

            ((Byteable) baseInterface).bytes(byteBufferBytes, 0);

            baseInterface.setInt(1);
            baseInterface.setStr("Hello World");

            Assert.assertEquals(1, baseInterface.getInt());
            Assert.assertEquals("Hello World", baseInterface.getStr());

        }
        {
            ExtInterface extInterface = DataValueClasses.newDirectReference(ExtInterface.class);
            byteBufferBytes.clear();
            ((Byteable) extInterface).bytes(byteBufferBytes, 0);
            extInterface.setInt2(43);

            Assert.assertEquals(1, extInterface.getInt());
            Assert.assertEquals(43, extInterface.getInt2());
            Assert.assertEquals("Hello World", extInterface.getStr());
            extInterface.setInt(2);

            Assert.assertEquals(2, extInterface.getInt());
        }
    }


    @Test
    public void test2() {
        IByteBufferBytes byteBufferBytes = ByteBufferBytes.wrap(ByteBuffer.allocate(1024));

        {
            ExtInterface extInterface = DataValueClasses.newDirectReference(ExtInterface.class);
            byteBufferBytes.clear();
            ((Byteable) extInterface).bytes(byteBufferBytes, 0);

            extInterface.setInt(1);
            extInterface.setInt2(2);
            extInterface.setStr("Hello World");

            Assert.assertEquals(1, extInterface.getInt());
            Assert.assertEquals(1, extInterface.getInt());
            Assert.assertEquals("Hello World", extInterface.getStr());
        }

        {
            BaseInterface baseInterface = DataValueClasses.newDirectReference(BaseInterface.class);
            byteBufferBytes.clear();
            ((Byteable) baseInterface).bytes(byteBufferBytes, 0);

            Assert.assertEquals(1, baseInterface.getInt());
            Assert.assertEquals("Hello World", baseInterface.getStr());
        }
    }


    public interface BaseInterface {

        String getStr();

        void setStr(@MaxSize(15) String str);

        int getInt();

        void setInt(int i);

    }

    public interface ExtInterface extends BaseInterface {

        int getInt2();

        @Group(1)
        void setInt2(int i);

    }
}