Question

如果用户未填写字段'editTextNomeVelhinho'，则我需要单击'b_avanca_c'按钮，并显示对话框警报，并且在用户填写'editText'后，必须转发布局'C_aviso'，以及如果'从头开始填充editText”。在这种情况下，应用将始终为“ if”，即使在对话框中填充后也始终会出现。

   fun b_avancar_c(view: View) {
    val nomeIdoso :String
    nomeIdoso=editTextNomeVelhinho.text.toString()

    if(editTextNomeVelhinho.text.isEmpty()) {
        buttonComecar.setOnClickListener {
            val builder = AlertDialog.Builder(this@B_menu)
            builder.setTitle("Atenção")
            builder.setMessage("Deve colocar o seu nome para continuar")
            builder.setPositiveButton("Continuar") { dialog, which ->
                //Toast.makeText(applicationContext, "continuar", Toast.LENGTH_SHORT).show()
            }
            val dialog: AlertDialog = builder.create()
            dialog.show()


        }
    }
    else {
        val it = Intent(this, C_aviso::class.java)
        startActivity(it)
    }
}

代码布局

    <?xml version="1.0" encoding="utf-8"?>
    <android.support.constraint.ConstraintLayout                 xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context="com.example.asus.aprendecomigovelhinho.B_menu">


        <Button
            android:id="@+id/buttonComecar"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginBottom="8dp"
            android:layout_marginEnd="8dp"
            android:layout_marginStart="8dp"
            android:layout_marginTop="8dp"
            android:background="@android:color/holo_green_dark"
            android:text="Começar"
            android:onClick="b_avancar_c"
            android:textColor="@android:color/background_light"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.983"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.349" />


        <EditText
            android:id="@+id/editTextNomeVelhinho"
            android:layout_width="320dp"
            android:layout_height="wrap_content"
            android:layout_marginBottom="8dp"
            android:layout_marginEnd="8dp"
            android:layout_marginStart="8dp"
            android:layout_marginTop="8dp"
            android:ems="10"
            android:inputType="text"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.921"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.026" />



            </android.support.constraint.ConstraintLayout>

Answer 1

单击按钮时会获得来自edittext的文本，因此每次都不会为空。

fun b_avancar_c(view: View) {
    val nomeIdoso :String
    nomeIdoso=editTextNomeVelhinho.text.toString()

    if(editTextNomeVelhinho.text.isEmpty()) {
        buttonComecar.setOnClickListener {
             val builder = AlertDialog.Builder(this@B_menu)
             builder.setTitle("Atenção")
             builder.setMessage("Deve colocar o seu nome para continuar")
             builder.setPositiveButton("Continuar") { dialog, which -> 
           //Toast.makeText(applicationContext,"continuar",Toast.LENGTH_SHORT).show()
           }
             val dialog: AlertDialog = builder.create()
             dialog.show()
           }
     }
     else {
           val it = Intent(this, C_aviso::class.java)
           startActivity(it)
     }
}

Answer 2

这里是一个简单的示例，说明如何使用https://developer.android.com/guide/topics/ui/dialogs文档中的Kotlin使用警报对话框

val builder: AlertDialog.Builder? = activity?.let {
        AlertDialog.Builder(it)
    }

    builder!!.setMessage("Are you sure you want to log out?")
        .setTitle("Log Out")

    builder.apply {
        setPositiveButton(R.string.user_log_out_dialog_no) { dialog, id ->
            val selectedId = id
        }
        setNegativeButton(R.string.user_log_out_dialog_yes) { dialog, id ->
            val selectedId = id
        }
    }
    val dialog: AlertDialog? = builder.create()

    dialog!!.show()

请记住，有些字符串是经过硬编码的。

Kotlin中的对话框警报

2 个答案: