나이 계산 Activity / import java.util.Calendar;

 

 

 

MainActivity.java

package com.bpdev.cat;
import androidx.appcompat.app.AppCompatActivity;

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

import com.google.android.material.snackbar.Snackbar;

import java.util.Calendar;


public class MainActivity extends AppCompatActivity {

    EditText editYear;
    Button btnYear;
    TextView txtResult;

    @Override
    protected void onCreate(Bundle savedInstanceState) { // 가장 먼저 실행
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        editYear = findViewById(R.id.editYear);
        btnYear = findViewById(R.id.btnYear);
        txtResult = findViewById(R.id.txtResult);

        btnYear.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                String strYear = editYear.getText().toString().trim();
                if (strYear.isEmpty()){
                    Snackbar.make(btnYear, "필수 항목은 꼭 입력하세요.", Snackbar.LENGTH_SHORT).show();
                    return;
                }

                Integer intYear = Integer.parseInt(strYear);

                Calendar now = Calendar.getInstance();
                Integer result = now.get(Calendar.YEAR) - intYear;

                txtResult.setText(result+"살 입니다.");

            }
        });

    }
}

 

 

 

activity_main.xml

Code

<?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">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="250dp"
        android:layout_height="250dp"
        android:layout_marginStart="55dp"
        android:layout_marginTop="100dp"
        android:layout_marginEnd="56dp"
        android:scaleType="centerCrop"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:srcCompat="@drawable/cat2" />

    <EditText
        android:id="@+id/editYear"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="100dp"
        android:layout_marginTop="40dp"
        android:layout_marginEnd="100dp"
        android:ems="10"
        android:gravity="center|center_vertical"
        android:hint="연도 4자리를 입력하세요"
        android:inputType="number"
        android:textColorHint="#CACACA"
        android:textSize="20sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/imageView" />

    <Button
        android:id="@+id/btnYear"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="159dp"
        android:layout_marginTop="30dp"
        android:layout_marginEnd="158dp"
        android:paddingLeft="20dp"
        android:paddingRight="20dp"
        android:text="생일 계산 하기"
        android:textSize="20sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/editYear" />

    <TextView
        android:id="@+id/txtResult"
        android:layout_width="0dp"
        android:layout_height="50dp"
        android:layout_marginStart="100dp"
        android:layout_marginTop="40dp"
        android:layout_marginEnd="100dp"
        android:backgroundTint="#FF4444"
        android:gravity="center|center_vertical"
        android:hint="몇 살일까요?"
        android:text="몇 살일까요?"
        android:textColorHint="#C6C6C6"
        android:textSize="24sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/btnYear" />
</androidx.constraintlayout.widget.ConstraintLayout>

Design