testConcurrencyFunction not use let

testConcurrencyFunction_not_use_let.kt

    fun testConcurrencyFunction(){
        Timer("thread_name_1").schedule(0) {
            if (string != null) {
                for (i in 1..10) {
                    Log.i("thread_name_1", "$i")
                    Log.i("thread_name_1", "string len: ${string!!.length}")
                    sleep(1000)
                }
            }

        }

        Timer("thread_name_2").schedule(0) {
            for (i in 1..10) {
                Log.i("thread_name_2", "$i")
                sleep(900)
                if (i >= 5) {
                    string = null
                }
            }
        } 
    }