private void setprefix(Player player, String prefix) { File file = fileManager.loadFile( plugin.getDataFolder().toString() + "\\players", player.getUniqueId().toString() + ".json"); String json = null; try { json = jsonManager.getJson(file); } catch (IOException e) { e.printStackTrace(); } JsonObject playerdata = jsonManager.createJsonObject(json); playerdata.getAsJsonObject("Player").addProperty("prefix", prefix); String json1 = jsonManager.toJson(playerdata); player.setDisplayName(coloring(prefix + player.getName())); jsonManager.writeJson(file, json1); }