In previous post we have looked at how we can improve performance when working with TextView and Spannables.

In this post we will explore ways to make setting of text on TextView faster.

If you look at the source code of setText method you can see that it does a lot of heavy lifting - there is measuring, drawing and object allocations, all of which run on the main thread.
That is why setting a large amounts of text on a TextView might result in UI stutters and hangs, not the smooth experience the user expects.

Fortunately for us there is something that can help us to remediate that - PrecomputedText, in this post we will look at how we can use it to improve TextView performance.


In simple terms PrecomputedText is a text object that contains both the text and layout measurements. When we use it to set text on a TextView no further layout calculations are required which is why it will be faster.


In order to create PrecomputedText we need to pass the text and TextMetricsParams of the target TextView to PrecomputedTextCompat.create method. Since it does heavy text layout measurements its best to call it from a background thread.

In the below code snippet we can see a full working example using Kotlin coroutines

fun TextView.setTextAsync(text: String) {
    val textView = this
    (context as? AppCompatActivity)?.lifecycleScope?.launch {
        val params = TextViewCompat.getTextMetricsParams(textView)
        val precomputedText = withContext(Dispatchers.Default) {
            PrecomputedTextCompat.create(text, params)
        TextViewCompat.setPrecomputedText(textView, precomputedText)

Now I haven’t measured the performance differences myself. However according to Google measuring text can take up to 90% of the time required to set the text.
Thanks to the above code snippet we can do all of that in the background without blocking the main thread.


Since EditText is a thin layer on top of TextView you might expect the above to work on EditText as well. Well you are wrong.

PrecomputedText appears to work only with TextView and StaticLayout. You might try to use EditText with the above code snippet but the result will be exactly like calling setText.

Looking at the source code of TextView there is a check in the setText method

if (type == BufferType.EDITABLE || getKeyListener() != null
        || needEditableForNotification) {

If the type is BufferType.EDITABLE (BufferType used by EditText) then the precomputedText will not be used.

Thanks for reading!
In this post we have learned have to make setText method of TextView faster!