IllegalStateException是否确定它是数据类型的？

Question

<?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="tenge.millionaire.MainActivity">

    <EditText
        android:id="@+id/monthlysalary"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:ems="10"
        android:hint="Enter monthly salary"
        android:inputType="textPersonName"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.502"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/perday"
        android:layout_width="wrap_content"
        android:layout_height="0dp"
        android:layout_marginTop="56dp"
        android:text="TextView"
        android:textSize="18sp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/monthlysalary" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="296dp"
        android:text="Show me :)"
        android:onClick="CaculateAge"
        android:background="@color/colorPrimary"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/perday" />
</android.support.constraint.ConstraintLayout>

package tenge.millionaire

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        perday.setText("");
    }

    public fun CaculateAge(view: View){
        val salary: String = perday.text.toString();
        val perday1 = salary.toInt()/30;
        perday.setText("Per day you earn $perday1")
    }
}

Answer 1

perday.setText("");

那么稍后您将尝试使用此值并将其放入此处：

val salary: String = perday.text.toString();
val perday1 = salary.toInt()/30;

工资现在只是一个空字符串，在那里它崩溃了。

 Caused by: java.lang.NumberFormatException: For input string: ""

您需要让perday包含一个数字。现在您说的是“”.ToInt（）,这会导致NumberFormatException