안드로이드 스튜디오 - BMI 계산기 만들기

 

 

MainActivity

import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import android.widget.Button
import android.widget.EditText
import android.widget.Toast

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val heightEditText: EditText = findViewById(R.id.heightEditText)
        val weightEditText: EditText = findViewById(R.id.weightEditText)
        val resultButton: Button = findViewById(R.id.resultButton)

        resultButton.setOnClickListener{
            Log.d("MainActivity", "Result버튼의 클릭되었음")
            if(heightEditText.text.isEmpty() || weightEditText.text.isEmpty()) {
                Toast.makeText(this, "빈 값이 있습니다.", Toast.LENGTH_SHORT).show()
                return@setOnClickListener
            }
            val height: Double = heightEditText.text.toString().toDouble()
            val weight: Double = weightEditText.text.toString().toDouble()

            val intent = Intent(this, ResultActivity::class.java)
            intent.putExtra("height", height)
            intent.putExtra("weight", weight)
            startActivity(intent)
        }
    }
}

activity_main

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:orientation="vertical"
    android:padding="16dp"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="50dp"
        android:gravity="center"
        android:text="비만도 계산기"
        android:textColor="@color/custom_black"
        android:textSize="30sp" />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="당신의 키(cm)"
        android:textColor="@color/custom_black"
        android:textSize="20sp"
        android:textStyle="bold" />

    <EditText
        android:id="@+id/heightEditText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:ems="10"
        android:inputType="numberDecimal" />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="30dp"
        android:text="당신의 몸무게(kg)"
        android:textColor="@color/custom_black"
        android:textSize="20sp"
        android:textStyle="bold" />

    <EditText
        android:id="@+id/weightEditText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:ems="10"
        android:inputType="numberDecimal" />

    <Button
        android:id="@+id/resultButton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="50dp"
        android:text="계산하기" />
</LinearLayout>

ResultActivity

import android.os.Bundle
import android.util.Log
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
import kotlin.math.pow

class ResultActivity : AppCompatActivity(){
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_result)

        val height = intent.getDoubleExtra("height", 0.0)
        val weight = intent.getDoubleExtra("weight", 0.0)
        val bmi:Double = weight / (height / 100).pow(2.0)
        val resultText:String = when{
            bmi >= 35.0 -> "고도 비만"
            bmi >= 30.0 -> "중도 비만"
            bmi >= 25.0 -> "경도 비만"
            bmi >= 23.0 -> "과체중"
            bmi >= 18.5 -> "정상"
            else -> "저체중"
        }

        val resultValueTextView: TextView = findViewById(R.id.bmiResultTextView)
        val resultStringTextView:TextView = findViewById(R.id.resultTextView)

        resultValueTextView.text = bmi.toString()
        resultStringTextView.text = resultText
    }
}

activity_result

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:paddingBottom="20dp">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="BMI : "
            android:textColor="@color/custom_black"
            android:textSize="24dp"
            android:textStyle="bold" />

        <TextView
            android:id="@+id/bmiResultTextView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="24dp"
            android:textStyle="bold"
            tools:text="23.111111" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="결과는 : "
            android:textColor="@color/custom_black"
            android:textSize="24dp"
            android:textStyle="bold" />

        <TextView
            android:id="@+id/resultTextView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="24dp"
            android:textStyle="bold"
            tools:text="과체중입니다." />

    </LinearLayout>

</LinearLayout>