So I have been updating a mod from 1.6.4 to 1.7.10, and some code that adds a custom class to an array when you place a block seems to add said class to an array twice. Here is the code:

@Override
public void onBlockAdded(World world, int i, int j, int k)
{
hasPlaced = true;
Marker ma;
markers.add(ma = new Marker(i, j, k, world.provider.dimensionId));
String markerCaption = "";
String helpText = "";

if (markers.size() == 1)
{
markerCaption = "Front-Left";
helpText = "You can place two more markers to mark out an area for a farm or mine etc. If you wish to do this, place another marker at the front-right position now";
System.out.println(markers.size());
}
else if (markers.size() == 2)
{
markerCaption = "Front-Right";
helpText = "Finally, place a marker at the Rear-Left position";
System.out.println(markers.size());
}
else if (markers.size() == 3)
{

markerCaption = "Rear-Left";
helpText = "You're done, now you can place down a mining box, farming box or right-click the front-left marker to copy a structure!";
System.out.println(markers.size());
}

else
{
System.out.println(markers.size());
markerCaption = "Too many Markers!";
}

if (markers.size() < 4)
{
V3 pos = new V3((double)i, (double)j, (double)k, world.provider.dimensionId);
pos.y += 0.01d;

if (ModSimukraft.configEnableMarkerAlignmentBeams)
{
EntityAlignBeam beam = new EntityAlignBeam(world);
ma.caption = markerCaption;
beam.setLocationAndAngles(pos.x, pos.y, pos.z, 0f, 0f);
beam.yaw = 0f;

if (!world.isRemote)
{
world.spawnEntityInWorld(beam);
}

ma.beams.add(beam);
EntityAlignBeam beam2 = new EntityAlignBeam(world);
beam2.setLocationAndAngles(pos.x, pos.y, pos.z, 90f, 0f);
beam2.yaw = 90f;

if (!world.isRemote)
{
world.spawnEntityInWorld(beam2);
}

ma.beams.add(beam2);
EntityAlignBeam beam3 = new EntityAlignBeam(world);
beam3.setLocationAndAngles(pos.x, pos.y, pos.z, 180f, 0f);
beam3.yaw = 180f;

if (!world.isRemote)
{
world.spawnEntityInWorld(beam3);
}

ma.beams.add(beam3);
EntityAlignBeam beam4 = new EntityAlignBeam(world);
beam4.setLocationAndAngles(pos.x, pos.y, pos.z, 270f, 0f);
beam4.yaw = 270f;

if (!world.isRemote)
{
world.spawnEntityInWorld(beam4);
}

ma.beams.add(beam4);
}
}

if (!helpText.contentEquals(""))
{
ModSimukraft.sendChat(helpText);
}

super.onBlockAdded(world, i, j, k);
}

So I should check to see what side is being run, and only add it if it client sided?

Well, only the person placing the markers should see the effects of them, so I guess that's the way to go.

The effects stay for as long as the block(s) exist

The effects are the spawning of a few lines to show how big an area will be, the area is marked out by the markers that are placed. Also, it checks to see how many markers have been placed, and any more than three means it will not work, however, since it adds two to the array, it thinks I have placed three when in fact I have only placed two

I used @SideOnly(Side.SERVER) but the code doesn't run properly. Could I consider making a packet message for this function?

You will need to do this serverside.

Use an

IExtendedEntityProperties

to keep track of which blocks the player has placed. Use

onBlockPlacedBy

to detect when it is placed.

You will need to do this serverside.

Use an

IExtendedEntityProperties

to keep track of which blocks the player has placed. Use

onBlockPlacedBy

to detect when it is placed.

 

onBlockPlacedBy does not override any method.

Surely if onBlockPlacedBy errors if you give it an @Override then the method doesn't already exist, meaning it won't be called when placing a block? I may be wrong, but that's what I think.

Ah, okay, I understand now, if the parameters are not correct, Java sees it as a new function. However, this function is also run on both the integrated server and the client, and I still need to add a marker to the array.

What do you mean it's in the wrong place? I'm really sorry that I seem so stupid, it's just I'm not very experienced with Java. C# is my specialty.