when I use setBlock the block appears then disappears. this is my code ...

public boolean onCast(EntityPlayer player, int x, int y, int z) {
	y += 1;
	World world = player.worldObj;
	if (world.getBlock(x, y, z) == Blocks.water) {
		world.setBlock(x, y, z, Blocks.ice);
                        return true;
	}
	return false;
}

 

the x, y, z is the block the player right clicks.

it Is called in the "onItemUse()" method of a item. p.s. I am new to minecraft modding.

like this?

        @Override
public boolean onCast(EntityPlayer player, int x, int y, int z) {
	y += 1;
	World world = player.worldObj;
	if (!world.isRemote) {
		if (world.getBlock(x, y, z) == Blocks.water) {
			world.setBlock(x, y, z, Blocks.ice);
		}
		return true;
	}
	return false;
}

I have tried it as

if (!world.isRemote)

and

if (world.isRemote)

and it still will not work.

I got it to work by add "!world.isremote" tests to where "onCast()" is called.