android - Android:将数据发送回MainActivity

我有3个 Activity :主要->饮料-> DrinkAlcohol
我按顺序浏览它们，但是我想从DrinkAlcohol中获取结果并将其发送给Main。

在DrinkAlcohol中，我使用SetResult；在Main中，我使用onActivityResult。但是我被困在DrinkAlcohol页面上，我做错了什么？

DrinkAlcohol XML按钮

<android.support.design.widget.FloatingActionButton
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginBottom="24dp"
    android:layout_marginEnd="24dp"
    android:clickable="true"
    android:onClick="gotoMain"
    app:srcCompat="@drawable/ic_home_black_24dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent" />

DrinkAlcohol goto主要功能:

fun gotoMain(view: View){
    val radioButtonID = mRg?.checkedRadioButtonId
    val rb = findViewById<RadioButton>(radioButtonID!!)
    val checkedValue = rb.text.toString().replace("%","").toDouble()
    val asu = mSize*checkedValue/60
    logDrink(asu)

    val intent = Intent(this, MainActivity::class.java)
    val returnIntent = this.intent
    returnIntent.putExtra("asu", asu)
    setResult(Activity.RESULT_OK, returnIntent)
}

MainActivity接收代码:

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    super.onActivityResult(requestCode, resultCode, data)

    if (requestCode == RETURN_DRINK_ACTIVITY) {
        if (resultCode == Activity.RESULT_OK) {
            val asu:Double  = data!!.extras.get("asu").toString().toDouble()
            updateDailyDrinks(asu)
            updateDailyBudget(asu)
            updateWeeklyBudget(asu)
            updateBAC(asu)

        }
    }
}

我希望获得MainActivity页面，该页面将触发一组Toasts，但实际上我什么也没得到，我只留在DrinkAlcohol Page(Activity)上。

我想念什么？

调用DrinkAlcohol的代码:

fun getDrinkSize(view: View){
    val size: Double = view.getTag().toString().toDouble()
    Toast.makeText(this, "The Drink is $size", Toast.LENGTH_LONG).show()

    var intent = Intent(this,DrinkAlcoholActivity::class.java )
    intent.putExtra("size", size)
    startActivity(intent)
}

最佳答案

setResult()不会将您带到任何其他 Activity 。

而不是setResult(Activity.RESULT_OK, returnIntent)，您应该这样做

intent.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);// If an instance of this Activity already exists, then it will be moved to the front. If an instance does NOT exist, a new instance will be created.
startActivity(intent);

而在您的MainActivity onCreate()中，

Bundle bundle= getIntent().getExtras();
if(bundle !=null){
// get your data here
}

您不需要onActivityResult()。
代码在Java中，因为我不知道Kotlin，对不起:)