String Parsing Logic for JSON UI | Bedrock Add-Ons | Page 1

"bindings": [

  /* ---------- #value1 ---------- */

  {
    "binding_type": "view",
    "source_property_name": "('a' + #text - 'hover_chat')",
    "target_property_name": "#f_text"
  },

  {
    "binding_type": "view",
    "source_property_name": "(#f_text - 'a')",
    "target_property_name": "#len1_num"
  },

  {
    "binding_type": "view",
    "source_property_name": "(('%.' + #len1_num + 's') * (#f_text - ('%.4s' * #f_text)))",
    "target_property_name": "#value1"
  },

  {
    "binding_type": "view",
    "source_property_name": "('a' + #f_text - ('%.4s' * #f_text) - #value1)",
    "target_property_name": "#rest1"
  },

  /* ---------- #value2 ---------- */

  {
    "binding_type": "view",
    "source_property_name": "(#rest1 - 'a')",
    "target_property_name": "#len2_num"
  },

  {
    "binding_type": "view",
    "source_property_name": "(('%.' + #len2_num + 's') * (#rest1 - ('%.4s' * #rest1)))",
    "target_property_name": "#value2"
  },

  {
    "binding_type": "view",
    "source_property_name": "('a' + #rest1 - ('%.4s' * #rest1) - #value2)",
    "target_property_name": "#rest2"
  },

  /* ---------- #value3 ---------- */

  {
    "binding_type": "view",
    "source_property_name": "(#rest2 - 'a')",
    "target_property_name": "#len3_num"
  },

  {
    "binding_type": "view",
    "source_property_name": "(('%.' + #len3_num + 's') * (#rest2 - ('%.4s' * #rest2)))",
    "target_property_name": "#value3"
  }

]

When working with Minecraft Bedrock UI JSON bindings, there is no native function for splitting strings or parsing dynamic segments.
To overcome this limitation, I implemented a length-based packed string format that allows multiple dynamic values to be safely transferred and decoded inside UI bindings.

Data Format

<prefix><len1><string1><len2><string2><len3><string3>...

ex: hover_chat003abc002de001f
-> value1: abc, value2: de, value3: f

All length fields must represent byte length, not character count.

This is critical because:

Bedrock UI string operations work on raw byte sequences
Multibyte characters (Korean, Chinese, emoji, etc.) will break character-based lengths

❌ Character length → causes corrupted parsing
✅ Byte length → always safe

"한" = 3 bytes (UTF-8)
"😊" = 4 bytes

#String Parsing Logic for JSON UI

Data Format