1. XML 파일 코드

<?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=".NewPost"
    android:background="@color/white">

    <ImageView
        android:id="@+id/iv_logo"
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:src="@drawable/logo"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.023" />

    <Button
        android:layout_width="50dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:background="@drawable/profile"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.847"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <View
        android:id="@+id/separator"
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:layout_marginTop="88dp"
        android:background="@color/black"
        app:layout_constraintTop_toTopOf="parent"
        tools:layout_editor_absoluteX="0dp" />

    <TextView
        android:id="@+id/tv_title"
        android:layout_width="30dp"
        android:layout_height="20dp"
        android:layout_marginStart="20dp"
        android:layout_marginTop="20dp"
        android:layout_marginEnd="4dp"
        android:ems="10"
        android:text="제목"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="@+id/separator"/>

    <EditText
        android:id="@+id/et_title"
        app:layout_constraintHorizontal_weight="1"
        android:layout_width="0dp"
        android:inputType="text"
        android:layout_height="20dp"
        android:layout_marginStart="4dp"
        android:layout_marginTop="0dp"
        android:layout_marginEnd="20dp"
        android:ems="10"
        android:text=""
        android:background="@drawable/et_rounded_border"
        app:layout_constraintStart_toEndOf="@+id/tv_title"
        app:layout_constraintTop_toTopOf="@+id/tv_title"
        app:layout_constraintEnd_toEndOf="parent"/>

    <TextView
        android:id="@+id/tv_memo"
        android:layout_width="30dp"
        android:layout_height="20dp"
        android:layout_marginStart="0dp"
        android:layout_marginTop="12dp"
        android:layout_marginEnd="4dp"
        android:ems="10"
        android:text="내용"
        app:layout_constraintStart_toStartOf="@+id/tv_title"
        app:layout_constraintTop_toBottomOf="@+id/tv_title"/>

    <EditText
        android:id="@+id/et_memo"
        app:layout_constraintHorizontal_weight="1"
        app:layout_constraintVertical_weight="1"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginStart="0dp"
        android:layout_marginTop="4dp"
        android:layout_marginEnd="20dp"
        android:layout_marginBottom="4dp"
        android:ems="10"
        android:text=""
        android:inputType="textMultiLine"
        android:background="@drawable/et_rounded_border"
        app:layout_constraintTop_toBottomOf="@+id/tv_memo"
        app:layout_constraintStart_toStartOf="@+id/tv_memo"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintBottom_toTopOf="@id/btn_post"/>

    <Button
        android:id="@+id/btn_post"
        app:layout_constraintHorizontal_weight="1"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="0dp"
        android:layout_marginBottom="20dp"
        android:layout_marginStart="20dp"
        android:layout_marginEnd="20dp"
        android:text="게시"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"/>


</androidx.constraintlayout.widget.ConstraintLayout>

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2. Kotlin 코드

package com.test.myapplication

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


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

        val title = findViewById<EditText>(R.id.et_title)
        val memo = findViewById<EditText>(R.id.et_memo)
        val post = findViewById<Button>(R.id.btn_post)


        // 제목과 내용 둘 중 하나라도 입력 안되면 토스트 메시지 띄우기
        post.setOnClickListener {
            if (title.text.toString().trim().isEmpty() || memo.text.toString().trim()
                    .isEmpty()
            ) {
                Toast.makeText(this, "제목과 내용 모두 입력해주세요.", Toast.LENGTH_SHORT).show()
                return@setOnClickListener
            }
            // 버튼 클릭 시 Topic 화면으로 이동 (TODO: OnePost를 Topic으로 바꾸세요)
            else {
                val intent = Intent(this, OnePost::class.java)
                intent.putExtra("title", title.text.toString())
                startActivity(intent)
            }
        }
    }
}

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3. 결과