[안드로이드 스튜디오 / Kotlin] 간단한 계산기 만들기

 

간단한 계산기 만드는 예제.

 

계산 결과는 소수점까지 표기, 0으로 나누는 것 에러 처리

 

MainActivity.kt

 

package com.example.myapplication

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        title = "테이블 레이아웃 계산기"

        btn0.setOnClickListener {
            if (Edit1.isFocused()) {
                val num = Edit1.getText().toString()
                if (!num.equals("0")) {
                    Edit1.setText(num + "0")
                }
            } else if (Edit2.isFocused()) {
                val num = Edit2.getText().toString()
                if (!num.equals("0")) {
                    Edit2.setText(num + "0")
                }
            }
        }
        btn1.setOnClickListener {
                if (Edit1.isFocused()) {
                    val num = Edit1.getText().toString()
                    if (!num.equals("0")) {
                        Edit1.setText(num + "1")
                    } else{
                        Edit1.setText("1")
                    }
                } else if (Edit2.isFocused()) {
                    val num = Edit2.getText().toString()
                    if (!num.equals("0")) {
                        Edit2.setText(num + "1")
                    } else {
                        Edit2.setText("1")
                    }
                }
        }

        btn2.setOnClickListener {
                if (Edit1.isFocused()) {
                    val num = Edit1.getText().toString()
                    if (!num.equals("0")) {
                        Edit1.setText(num + "2")
                    } else {
                        Edit1.setText("2")
                    }
                } else if (Edit2.isFocused()) {
                    val num = Edit2.getText().toString()
                    if (!num.equals("0")) {
                        Edit2.setText(num + "2")
                    } else {
                        Edit2.setText("2")
                    }
                }
        }
...
btn9.setOnClickListener {
            if (Edit1.isFocused()) {
                val num = Edit1.getText().toString()
                if (!num.equals("0")) {
                    Edit1.setText(num + "9")
                } else {
                    Edit1.setText("9")
                }
            } else if (Edit2.isFocused()) {
                val num = Edit2.getText().toString()
                if (!num.equals("0")) {
                    Edit2.setText(num + "9")
                } else {
                    Edit2.setText("9")
                }
            }
        }

        btnAdd.setOnClickListener {
                val num1 = Edit1.getText().toString()
                val num2 = Edit2.getText().toString()
                if (num1.trim().equals("") || num2.trim().equals("")) {
                    textView.setText("입력창이 비었습니다.")
                } else {
                    val result = num1.toDouble() + num2.toDouble();
                    textView.setText("계산 결과 : " + result.toString());
                }
        }

        btnSub.setOnClickListener {
            val num1 = Edit1.getText().toString()
            val num2 = Edit2.getText().toString()
            if (num1.trim().equals("") || num2.trim().equals("")) {
                textView.setText("입력창이 비었습니다.")
            } else {
                val result = num1.toDouble() - num2.toDouble();
                textView.setText("계산 결과 : " + result.toString());
            }
        }

        btnMul.setOnClickListener {
            val num1 = Edit1.getText().toString()
            val num2 = Edit2.getText().toString()
            if (num1.trim().equals("") || num2.trim().equals("")) {
                textView.setText("입력창이 비었습니다.")
            } else {
                val result = num1.toDouble()*num2.toDouble();
                textView.setText("계산 결과 : " + result.toString());
            }
        }

        btnDiv.setOnClickListener {
            val num1 = Edit1.getText().toString()
            val num2 = Edit2.getText().toString()
            if (num1.trim().equals("") || num2.trim().equals("")) {
                textView.setText("입력창이 비었습니다.")
            } else if(num1.equals("0") || num2.equals("0")) {
                textView.setText("0으로 나눌 수 없습니다.")
            }else{
                val result = num1.toDouble()/num2.toDouble();
                textView.setText("계산 결과 : " + result.toString());
            }
        }

    }
}

 

avtivity_main.xml

<?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">

    <LinearLayout
        android:id="@+id/linearLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        tools:layout_editor_absoluteX="-68dp"
        tools:layout_editor_absoluteY="33dp">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="125dp"
            android:orientation="vertical">

            <EditText
                android:id="@+id/Edit1"
                android:layout_width="match_parent"
                android:layout_height="56dp"
                android:layout_span="5"
                android:text=""
                android:textSize="15dp"
                />

            <EditText
                android:id="@+id/Edit2"
                android:layout_width="match_parent"
                android:layout_height="56dp"
                android:layout_span="5"
                android:text=""
                android:textSize="15dp" />

        </LinearLayout>

        <TableLayout
            android:layout_width="414dp"
            android:layout_height="127dp">

            <TableRow
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_margin="5dp">

                <Button
                    android:id="@+id/btn0"
                    android:layout_width="80dp"
                    android:layout_height="wrap_content"
                    android:textSize="20dp"
                    android:text="0" />
...
<Button
                    android:id="@+id/btn4"
                    android:layout_width="80dp"
                    android:layout_height="wrap_content"
                    android:textSize="20dp"
                    android:text="4" />
            </TableRow>

            <TableRow
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_margin="5dp">

                <Button
                    android:id="@+id/btn5"
                    android:layout_width="80dp"
                    android:layout_height="wrap_content"
                    android:textSize="20dp"
                    android:text="5" />
...
<Button
                    android:id="@+id/btn9"
                    android:layout_width="80dp"
                    android:layout_height="wrap_content"
                    android:textSize="20dp"
                    android:text="9" />
            </TableRow>

        </TableLayout>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical">

            <Button
                android:id="@+id/btnAdd"
                android:layout_width="match_parent"
                android:layout_height="60dp"
                android:text="더하기"
                android:textSize="25dp"

                android:layout_margin="3dp"/>

            <Button
                android:id="@+id/btnSub"
                android:layout_width="match_parent"
                android:layout_height="60dp"
                android:text="빼기"
                android:textSize="25dp"

                android:layout_margin="3dp"/>

            <Button
                android:id="@+id/btnMul"
                android:layout_width="match_parent"
                android:layout_height="60dp"
                android:text="곱하기"
                android:textSize="25dp"
                android:layout_margin="3dp"/>

            <Button
                android:id="@+id/btnDiv"
                android:layout_width="match_parent"
                android:layout_height="60dp"
                android:text="나누기"
                android:textSize="25dp"
                android:layout_margin="3dp"/>

            <TextView
                android:id="@+id/textView"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="계산결과 : "
                android:textColor="#FF0000"
                android:textSize="30dp"/>
        </LinearLayout>

    </LinearLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

 

 

실행 결과