Kotlin-按下按钮时运行打印语句

Question

我是一名Swift开发人员，我刚刚加入Kotlin，所以我不熟悉事情的运作方式。

在Swift中，如果我创建一个按钮并向其中添加一个动作/目标，然后在该动作中我添加一个print statement，则会在控制台中将其打印出来。

lazy var myButton: UIButton = {
    let button = UIButton(type: .system)
    // create button
    button.addTarget(self, action: #selector(myButtonPressed), for: .touchUpInside)
    return button
}()

@objc func myButtonPressed() {
    print("this gets printed to the console")
}

但是在Kotlin中，当我有print statement时，什么都不会打印到Build Output或Event Log

val myButton: Button = findViewById(R.id.myButtonId)
myButton.setOnClickListener { myButtonPressed() }

private fun myButtonPressed() {
    print("nothing gets printed to the console, I have to use the Toast function")
}

我必须使用

private fun myButtonPressed() {
    Toast.makeText(this, "this briefly appears inside the emulator", Toast.LENGTH_SHORT).show()
}

我是在做错事还是应该以这种方式工作？

Answer 1

我必须添加才能使用Log.d()，并且必须在Debug mode中运行它：

import android.util.Log // *** 1. include this import statement ***

private val TAG = "MainActivity" // *** 2. add this constant, name it TAG and set the value to the name of the Activity ***

val myButton: Button = findViewById(R.id.myButtonId)
myButton.setOnClickListener { myButtonPressed() }

private fun myButtonPressed() {

    Log.d(TAG, ">>>>> now this prints to the console <<<<<<") // *** 3. add the TAG inside the first param inside the Log.d statement ***
}