Lazy optional IItemHandler problem

Hi i'm new to minecraft modding so i'm trying to learn. I'm having issues with an LazyOptional<IItemHandler> variable what i want to do is get the boolean from itemhandler.isItemValid and put it in an condition. but when i do 

itemhandler.ifPresent(h -> h.isItemValid(1, state.getBlock().getItem(world, blockpos, state))); it says to me that itemhandler.ifPresent is a void method i understand but i can't find an other way to get to the return of h.isItemValid

Thank u anyhelp would be cool and sry for bad english.

here is the method:

private void Looting(BlockState state, BlockPos blockpos, PlayerEntity player) {
		
		LazyOptional<IItemHandler> itemhandler;
		TileEntity chest;
		
		if(world.getBlockState(pos.add(0, 1, 0)) == BlockInit.harvest_chest.getDefaultState()) {
			chest = world.getTileEntity(pos.add(0, 1, 0));
			itemhandler = chest.getCapability(CapabilityItemHandler.ITEM_HANDLER_CAPABILITY, null);
          
          
          //test
			itemhandler.ifPresent(h -> h.isItemValid(1, state.getBlock().getItem(world, blockpos, state)));
          //test
			
			for(io = 0; io < 36; io++) {
              
              //condition that needs test
				if(itemhandler) itemhandler.ifPresent(h -> h.insertItem(io, state.getBlock().getItem(world, blockpos, state), false));
              //condition
              
              
			}
		}
		else if(getDistancetoBlock(player, pos)) {
			player.addItemStackToInventory(state.getBlock().getItem(world, blockpos, state));
			player.sendStatusMessage(new StringTextComponent("HELLO"), true);
		}
		else {
			Block.spawnDrops(state, world, pos.add(0, 1, 0), this.getTileEntity(), null, ItemStack.EMPTY);
		}
	}