How to check if an index before a list item exists?-CodePudding

I have a list of objects with keys title, text and title again:

"data": [
        {
          "type": "title",
          "data": "Dashboard"
        },
        {
          "type": "text",
          "data": "This is your dashboard.."
        },
        {
          "type": "title",
          "data": "Fees"
        },
]

I am able to show these key values of key data on the screen:

I want to have a space between text and title if title comes after text. So i made an if else statement which substracts the index with 1 and check if the previous index contains key value text and then i want to show a SizedBox else i want to show an empty Container:

if ((json[index - 1]['type'] == "text") 
    
   SizedBox(height: 10)
else 
   Container(),

But i get error: RangeError (index): Invalid value: Not in inclusive range 0..3: -1 This means that it also substracts the first index with the key value title and that is the reason i get index vallue -1 back. So my question is how can i show SizedBox after text and then also resolve the error above?

CodePudding user response：

that's easily fixed by checking if the index is not 0, so change it to

if (index != 0 && json[index - 1]['type'] == "text")