What means "_" symbol in Kotlin?

Question

I tried to find information what it means but I didn't. Trying to understand what it does in this code:

checkBox.setOnCheckedChangeListener { _, isChecked ->
            if (isChecked) {
                // The toggle is enabled
            } else {
                // The toggle is disabled
            }
        }

Answer 1

The _ Used for

• substitutes an unused parameter in a lambda expression
• substitutes an unused parameter in a destructuring declaration

For more information check this Keywords and Operators

Answer 2

when user does't need a parameter in lembda expression then we can use "_"

 setOnTouchListener { _, p1 ->
            if (p1.action == MotionEvent.ACTION_DOWN) {
                hideKeyboard()
                true
            } else
                false
        }