코틀린/안드로이드/2020-05-03/ 계산기 예제

package com.example.application
 
 
import android.os.Bundle
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import kotlinx.android.synthetic.main.activity_main.*
 
 
 
 
class MainActivity : AppCompatActivity() {
 
 
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        class Calc {
            var num = 0
        }
 
 
        val calc = Calc()
        plus.setOnClickListener{
            val number = etext.text.toString()
            calc.num = Integer.parseInt(number)
            etext.setText("")
 
 
            Toast.makeText(this,
                "입력된 숫자 " + calc.num+"",Toast.LENGTH_LONG).show()
 
 
        }
        equal.setOnClickListener{
            var num1 = calc.num
            var num2 = Integer.parseInt(etext.text.toString())
            etext.setText((num1 + num2).toString())
        }
    }
}

 

 

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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=".MainActivity">
 
 
 
 
    <EditText
        android:id="@+id/etext"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="150dp"
        android:ems="10"
        android:inputType="textPersonName"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
 
 
    <Button
        android:id="@+id/plus"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="60dp"
        android:text="+"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/etext" />
 
 
    <Button
        android:id="@+id/minus"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="22dp"
        android:text="-"
        app:layout_constraintStart_toStartOf="@+id/plus"
        app:layout_constraintTop_toBottomOf="@+id/plus" />
 
 
    <Button
        android:id="@+id/multiply"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="28dp"
        android:text="*"
        app:layout_constraintStart_toStartOf="@+id/minus"
        app:layout_constraintTop_toBottomOf="@+id/minus" />
 
 
    <Button
        android:id="@+id/divid"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="26dp"
        android:text="/"
        app:layout_constraintStart_toStartOf="@+id/multiply"
        app:layout_constraintTop_toBottomOf="@+id/multiply" />
 
 
    <Button
        android:id="@+id/equal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="2dp"
        android:layout_marginTop="26dp"
        android:text="="
        app:layout_constraintStart_toStartOf="@+id/divid"
        app:layout_constraintTop_toBottomOf="@+id/divid" />
 
 
    <TextView
        android:id="@+id/textView3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="55dp"
        android:layout_marginTop="34dp"
        android:layout_marginEnd="55dp"
        android:gravity="center"
        android:textSize="50dp"
        android:text="계 산 기"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>