[Android 개발] 간단한 계산 기능 구현

화면 구성

 

MainActivity.java

package com.example.myapplication1;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    private static final String TAG = "MainActivity";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void Btn(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));
    }

    public void Btn2(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));
    }

    public void Btn3(View v){
        EditText number1 = (EditText) findViewById(R.id.Number1);
        EditText number2 = (EditText) findViewById(R.id.Number2);
        TextView result = (TextView) findViewById(R.id.Result);
        Float n1 = Float.parseFloat(number1.getText().toString());
        Float n2 = Float.parseFloat(number2.getText().toString());
        result.setText(Float.toString(n1/n2));
    }

    public void Btn4(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));
    }
}

 

activity_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">

    <EditText
        android:id="@+id/Number2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="1dp"
        android:layout_marginBottom="54dp"
        android:ems="10"
        android:inputType="number"
        app:layout_constraintBottom_toTopOf="@+id/Result"
        app:layout_constraintEnd_toEndOf="@+id/Number1"
        app:layout_constraintTop_toBottomOf="@+id/Number1"
        tools:text="입력 값 2" />

    <EditText
        android:id="@+id/Number1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="29dp"
        android:ems="10"
        android:inputType="number"
        app:layout_constraintBottom_toTopOf="@+id/Number2"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView"
        tools:text="입력 값 1" />


    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="22dp"
        android:onClick="Btn"
        android:text="더하기"
        android:visibility="visible"
        app:layout_constraintEnd_toStartOf="@+id/button2"
        app:layout_constraintHorizontal_chainStyle="packed"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="@+id/button2"
        tools:visibility="visible" />

    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="1dp"
        android:layout_marginBottom="8dp"
        android:onClick="Btn2"
        android:text="빼기"
        app:layout_constraintBottom_toTopOf="@+id/button4"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/button"
        app:layout_constraintTop_toBottomOf="@+id/Result" />

    <Button
        android:id="@+id/button3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="22dp"
        android:onClick="Btn3"
        android:text="나누기"
        app:layout_constraintEnd_toStartOf="@+id/button4"
        app:layout_constraintHorizontal_chainStyle="packed"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/button" />

    <Button
        android:id="@+id/button4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="1dp"
        android:layout_marginBottom="185dp"
        android:onClick="Btn4"
        android:text="곱하기"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/button3"
        app:layout_constraintTop_toBottomOf="@+id/button2" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginStart="20dp"
        android:layout_marginTop="78dp"
        android:layout_marginEnd="20dp"
        android:layout_marginBottom="56dp"
        android:text="계산이 가능합니다."
        android:textSize="60px"
        app:layout_constraintBottom_toTopOf="@+id/Number1"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/Result"
        android:layout_width="172dp"
        android:layout_height="0dp"
        android:layout_marginBottom="39dp"
        android:text="= 결과 값"
        app:layout_constraintBottom_toTopOf="@+id/button2"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/Number2"
        tools:ignore="MissingConstraints" />

</androidx.constraintlayout.widget.ConstraintLayout>