Kotlin ActivityMainBinding build id in for loop-CodePudding

I have a problem. In my xml file, I have multiple textViews with the following id's:

txtRow1Column1
txtRow1Column2
txtRow2Column1
txtRow2Column2
txtRow3Column1
txtRow3Column2
txtRow4Column1
txtRow4Column2

Now I filled an array with random numbers between 1..2 and using the 1 or 2 I want to add a text in the textview from the resources. For that I already have the following function:

private fun startNewRound() {

    // Define the array for (row, column, value)
    val rows = arrayOf<Array<Int>>();

    // Fill the array for each row and for each column
    for (row in 1..4) {
        rows.set(row, emptyArray())
        for (column in 1..2) {
            rows[row].plus((1..2).random())
        }
    }

    // Show the correct text using the filled array
    for (columns in rows) {
        for (value in columns) {
            val id = "txtRow"   rows.indexOf(columns)   "Column"   (columns.indexOf(value)   1)
            when (value) {
                1 -> binding."ID HERE".text = getString(R.string.strTrue)
                2 -> binding."ID HERE".text = getString(R.string.strFalse)
            }
        }
    }
}

Currently I have added "ID HERE" instead of the id of the view, because I need to use a string as id to bind to the view. My question is: How can I use that string to find the correct id and be able to bind to that specific view?

CodePudding user response：

Side note, the way you're building that 2D array looks like O(n^2), even if it wasn't going to throw IndexOutOfBoundsExceptions.

The way you're getting the column index won't work. Suppose you have the value 1 twice in a column. indexOf is going to return 0 both times because it returns the first valid match. Also, using indexOf inside your 2D loop results in O(n^3) complexity when it could just be O(n).

As to your problem, you can use Resources.getIdentifier() to find the Int ID of a view so you can find the view using findViewById. The alternative would be to use reflection on the binding class to find a field with that name, but that's uglier.

fun <T> View.getChildWithName(name: String): T {
    val id = context.resources.getIdentifier("id", name, context.packageName)
    return findViewById(id)
}

private fun startNewRound() {

    val rows = Array(4) { Array(2) { (1..2).random() } }

    rows.forEachIndexed { rowIndex, row ->
        row.forEachIndexed { colIndex, value ->
            val id = "txtRow${rowIndex   1}Column${colIndex    1}" 
            val view = binding.root.getChildWithName<TextView>(id)
            view.text = when (value) {
                1 -> getString(R.string.strTrue)
                2 -> getString(R.string.strFalse)
            }
        }
    }
}