안드로이드 - 1. 간단한 계산기 만들기

젤리빈 4.4 버전으로 작성되었습니다.

레이아웃은 단순히 입력을 받을 수 있는 EditText 상자 2개와

연산을 선택할 수 있는 버튼 4개

그리고 결과를 볼 수 있는 TextView 한개가 배치되어있습니다.

activity_main.xml

<?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.kch.tutorial2.MainActivity">

    <LinearLayout

        android:layout_width="368dp"

        android:layout_height="495dp"

        android:orientation="vertical"

    >

        <LinearLayout

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:orientation="vertical"

        >

            <EditText

                android:id="@+id/number1"

                android:layout_width="match_parent"

                android:layout_height="wrap_content"

                android:ems="10"

                android:inputType="number"

                android:text="number1"

             />

            <EditText

                android:id="@+id/number2"

                android:layout_width="match_parent"

                android:layout_height="wrap_content"

                android:ems="10"

                android:text="number2"

             />

        </LinearLayout>

        <LinearLayout

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:orientation="horizontal"

            tools:layout_editor_absoluteY="0dp"

            tools:layout_editor_absoluteX="0dp">

        <Button

            android:id="@+id/addbtn"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:text="add"

            android:onClick="addClick"

            />

        <Button

            android:id="@+id/subbtn"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:text="sub"

            tools:layout_editor_absoluteX="104dp"

            tools:layout_editor_absoluteY="120dp"

            android:onClick="subClick"

            />

        <Button

            android:id="@+id/mulbtn"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:text="mult"

            android:onClick="mulClick"

            />

        <Button

            android:id="@+id/divbtn"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:text="div"

            android:onClick="divClick"

            />

        </LinearLayout>

        <LinearLayout

            android:layout_width="wrap_content"

            android:layout_height="wrap_content">

            <TextView

                android:id="@+id/result"

                android:layout_width="wrap_content"

                android:layout_height="wrap_content"

                android:text="result"

                android:textAppearance="@style/TextAppearance.AppCompat.Display1" />

        </LinearLayout>

    </LinearLayout>

</android.support.constraint.ConstraintLayout>

MainActivity.java

간단한 메소드이므로 따로 설명하지는 않습니다.

package com.example.kch.tutorial2;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.view.View;

import android.widget.EditText;

import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

    }

    //덧셈 버튼 클릭시

    public void addClick(View v){

        EditText number1 = (EditText)findViewById(R.id.number1);

        EditText number2 = (EditText)findViewById(R.id.number2);

        TextView result = (TextView)findViewById(R.id.result);

        int n1 = Integer.parseInt(number1.getText().toString());

        int n2 = Integer.parseInt(number2.getText().toString());

        result.setText(Integer.toString(n1+n2));

    }

    //뺄셈버튼 클릭시

    public void subClick(View v){

        EditText number1 = (EditText)findViewById(R.id.number1);

        EditText number2 = (EditText)findViewById(R.id.number2);

        TextView result = (TextView)findViewById(R.id.result);

        int n1 = Integer.parseInt(number1.getText().toString());

        int n2 = Integer.parseInt(number2.getText().toString());

        result.setText(Integer.toString(n1-n2));

    }

    //곱셈버튼 클릭시

    public void mulClick(View v){

        EditText number1 = (EditText)findViewById(R.id.number1);

        EditText number2 = (EditText)findViewById(R.id.number2);

        TextView result = (TextView)findViewById(R.id.result);

        int n1 = Integer.parseInt(number1.getText().toString());

        int n2 = Integer.parseInt(number2.getText().toString());

        result.setText(Integer.toString(n1*n2));

    }

    //나눗셈 버튼클릭시

    public void divClick(View v){

        EditText number1 = (EditText)findViewById(R.id.number1);

        EditText number2 = (EditText)findViewById(R.id.number2);

        TextView result = (TextView)findViewById(R.id.result);

        int n1 = Integer.parseInt(number1.getText().toString());

        int n2 = Integer.parseInt(number2.getText().toString());

        result.setText(Integer.toString(n1/n2));

    }

}

소스 출처 : https://www.inflearn.com/course/%EC%95%88%EB%93%9C%EB%A1%9C%EC%9D%B4%EB%93%9C-%EC%8A%A4%ED%8A%9C%EB%94%94%EC%98%A4-%EC%95%88%EB%93%9C%EB%A1%9C%EC%9D%B4%EB%93%9C-%EC%95%B1-%EB%A7%8C%EB%93%A4%EA%B8%B0/