Solved Saving blockstates to hashmap error

Code:

    public Map<String, List<BlockState>> savedBlocks = new HashMap<String, List<BlockState>>();

I'm saving blockstates to that hashmap above but I get this error.
BlockState cannot be cast to java.util.List

Code:

Code:

@SuppressWarnings("unchecked")
    @EventHandler
    public void blockPlace(BlockPlaceEvent event) {
        Player p = event.getPlayer();
        List<BlockState> b = (List<BlockState>) event.getBlockReplacedState();
        if (plugin.skyblock.containsKey(p.getName())) {
            String arena = plugin.skyblock.get(p.getName());
            plugin.savedBlocks.put(arena, b);
        }
    }
   
    @SuppressWarnings("unchecked")
    @EventHandler
    public void blockBreak(BlockBreakEvent event) {
        Player p = event.getPlayer();
        List<BlockState> b = (List<BlockState>) event.getBlock().getState();
        if (plugin.skyblock.containsKey(p.getName())) {
            String arena = plugin.skyblock.get(p.getName());
            plugin.savedBlocks.put(arena, b);
        }
    }

 

Change the b variable to BlockState and when you put it in your HashMap, use map.get(arena).add(b).

 

Code:

@EventHandler
    public void blockPlace(BlockPlaceEvent event) {
        Player p = event.getPlayer();
        BlockState b = event.getBlockReplacedState();
        if (plugin.skyblock.containsKey(p.getName())) {
            String arena = plugin.skyblock.get(p.getName());
            plugin.savedBlocks.get(arena).add(b);
        }
    }

I get a NullPointerException on plugin.savedBlocks.get(arena).add(b);

 

slater96 if the HashMap doesn't contain the arena String key, use map.put(arena, new ArrayList<BlockState>). Then add the BlockState to the list.

 

Code:

@EventHandler
    public void blockPlace(BlockPlaceEvent event) {
        Player p = event.getPlayer();
        BlockState b = event.getBlockReplacedState();
        if (plugin.skyblock.containsKey(p.getName())) {
            String arena = plugin.skyblock.get(p.getName());
            plugin.savedBlocks.put(arena, new ArrayList<BlockState>());
            plugin.savedBlocks.get(arena).add(b);
        }
    }

It only seems to save one block. Thanks for your help so far though.

 

You should only add a new ArrayList if there is no ArrayList for the arena already. Check if savedBlcoks containsKey arena and only add the list if the key isn't already added.