Kotlin開發中與if等價的takeIf與takeUnless詳解

fun CheckMyTakeIf(value :Boolean):Boolean = value
fun main()
{
	//使用了takeIf簡化了程式碼
	var lll :String?= name.takeIf{
	        CheckMyTakeIf(true)
	    }
	print(lll)
}

fun CheckMyTakeIf(value :Boolean):Boolean = value
fun main()
{
	//未簡化程式碼
	var lll :String? = null
	if(CheckMyTakeIf(true))
	    lll = name
	else
	    lll = null
	print(lll)
}

fun CheckMyTakeIf(value :Boolean):Boolean = value
fun main()
{
    var name :String? = "你好"
    var lll = name.takeIf {
        CheckMyTakeIf(true)
        CheckMyTakeIf(false) //最後返回false，所以返回空null
    }
    println(lll)
    lll = name.takeIf{
        CheckMyTakeIf(false) 
        CheckMyTakeIf(true)  //最後返回ture，所以返回自身，自身就是name字串
    }
    println(lll)
}

fun CheckMyTakeIf(value :Boolean):Boolean = value
fun main()
{
    var name :String? = "你好"
    var lll = name.takeUnless {
        CheckMyTakeIf(true)
        CheckMyTakeIf(false)
    }
    println(lll)
    lll = name.takeUnless{
        CheckMyTakeIf(false)
        CheckMyTakeIf(true)
    }
    println(lll)
}

private val BluetoothAdapter.isDisabled: Boolean
    get() = !isEnabled
...
// Ensures Bluetooth is available on the device and it is enabled. If not,
// displays a dialog requesting user permission to enable Bluetooth.
bluetoothAdapter?.takeIf { it.isDisabled }?.apply {
    val enableBtIntent = Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE)
    startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT)
}

private val BluetoothAdapter.isDisabled: Boolean
    get() = !isEnabled

bluetoothAdapter?.takeIf { it.isDisabled }?.apply {
    val enableBtIntent = Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE)
    startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT)
}

private val BluetoothAdapter.isDisabled: Boolean
    get() = !isEnabled
...
// Ensures Bluetooth is available on the device and it is enabled. If not,
// displays a dialog requesting user permission to enable Bluetooth.
bluetoothAdapter?.takeIf { it.isDisabled }?.apply {
    val enableBtIntent = Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE)
    startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT)
}

bluetoothAdapter?.takeUnless { it.isEnabled }?.apply {
    val enableBtIntent = Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE)
    startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT)
}