diff --git a/7weeks/.gitignore b/7weeks/.gitignore
new file mode 100644
index 0000000..efaac43
--- /dev/null
+++ b/7weeks/.gitignore
@@ -0,0 +1,75 @@
+# OS files
+.DS_Store
+
+# Built application files
+*.apk
+*.ap_
+*.aab
+
+# Files for the ART/Dalvik VM
+*.dex
+
+# Java class files
+*.class
+
+# Generated files
+bin/
+gen/
+out/
+release/
+
+# Gradle files
+.gradle/
+build/
+
+# Local configuration file (sdk path, etc)
+local.properties
+
+# Proguard folder generated by Eclipse
+proguard/
+
+# Log Files
+*.log
+
+# Android Studio Navigation editor temp files
+.navigation/
+
+# Android Studio captures folder
+captures/
+
+# IntelliJ
+*.iml
+.idea
+
+# Keystore files
+# Uncomment the following lines if you do not want to check your keystore files in.
+#*.jks
+#*.keystore
+
+# External native build folder generated in Android Studio 2.2 and later
+.externalNativeBuild
+
+# Google Services (e.g. APIs or Firebase)
+# google-services.json
+
+# Freeline
+freeline.py
+freeline/
+freeline_project_description.json
+
+# fastlane
+fastlane/report.xml
+fastlane/Preview.html
+fastlane/screenshots
+fastlane/test_output
+fastlane/readme.md
+
+# Version control
+vcs.xml
+
+# lint
+lint/intermediates/
+lint/generated/
+lint/outputs/
+lint/tmp/
+# lint/reports/
diff --git a/7weeks/README.md b/7weeks/README.md
new file mode 100644
index 0000000..12d5885
--- /dev/null
+++ b/7weeks/README.md
@@ -0,0 +1,157 @@
+## ViewGroup
+
+- Android의 모든 위젯은 View를 상속하여 구현하고 있다.
+
+ 
+
+### 주요 ViewGroup 종류와 사용법
+
+#### LinearLayout
+
+- 명칭에서 알 수 있듯이 선형 모양의 레이아웃
+- `orientation` 이라는 필수 속성이 필요하며 지정하지 않을 경우 `horizontal` 이 기본
+
+```xml
+
+
+
+```
+
+#### RelativeLayout
+
+- 부모 또는 특정 View를 기준으로 특정 View의 상대 위치를 지정할 수 있는 레이아웃
+
+```xml
+
+
+
+
+
+
+
+```
+
+#### FrameLayout
+
+- 하나의 View 위젯을 표현하기 위한 레이아웃
+- 단, 레이아웃 하위에 여러 View 위젯을 추가할 순 있다.
+
+```xml
+
+
+
+
+
+```
+
+#### ConstraintLayout
+
+- 뷰와 뷰 사이에 제약조건을 설정하여 위젯을 배치하기 위한 레이아웃
+- 속성이 엄청나게 많습니다. ~~(알아서 찾아보세요...)~~
+
+```xml
+
+
+
+
+
+```
+
+### 주요 Widget 종류와 사용법
+
+#### RecyclerView
+
+- 기존의 ListView의 단점과 성능을 개선하여 제공되는 위젯
+- ViewHolder 패턴을 강제하여 아이템 View의 재사용성을 적극 활용한다.
+
+```xml
+
+```
+
+```kotlin
+fun setupRecyclerView() {
+ ExampleAdapter adapter = new ExampleAdapter()
+ LinearLayoutManager layoutManager = new LayoutManager(this)
+ with(exampleList) {
+ this.layoutManager = layoutManager
+ this.adapter = adpater
+ }
+}
+```
+
+```kotlin
+class ExampleAdapter : RecyclerView.Adapter() {
+ private var dataSet = mutableListOf()
+
+ fun addItems(items: List) {
+ dataSet.addAll(items)
+ notifyDataSetChanged()
+ }
+
+ fun updateItems(items: List) {
+ dataSet = items as MutableList
+ notifyDataSetChanged()
+ }
+
+ class ExampleHolder(val containerView: View) : RecyclerView.ViewHolder(view) {
+ // other code
+ }
+
+
+ abstract class LayoutContainerViewHolder(override val containerView: View) : RecyclerView.ViewHolder(containerView)
+
+ override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ExampleHolder {
+ return ExampleHolder(
+ LayoutInflater.from(parent.context).inflate(R.layout.item_example, parent, false)
+ )
+ }
+
+ override fun onBindViewHolder(holder: ExampleHolder, position: Int) {
+ // otehr code...
+ }
+
+ override fun getItemCount(): Int = dataSet.size
+}
+```
+
+#### ViewPager
+
+- 스와이프 액션을 통해 화면을 이동하기 위한 위젯
+- ~~샘플 코드 귀찮아요...~~
+
+```xml
+
+```
+
diff --git a/7weeks/app/.gitignore b/7weeks/app/.gitignore
new file mode 100644
index 0000000..796b96d
--- /dev/null
+++ b/7weeks/app/.gitignore
@@ -0,0 +1 @@
+/build
diff --git a/7weeks/app/build.gradle b/7weeks/app/build.gradle
new file mode 100644
index 0000000..b95d92c
--- /dev/null
+++ b/7weeks/app/build.gradle
@@ -0,0 +1,45 @@
+apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-android-extensions'
+
+android {
+ compileSdkVersion 28
+ buildToolsVersion "29.0.0"
+ defaultConfig {
+ applicationId "io.cro.example"
+ minSdkVersion 21
+ targetSdkVersion 28
+ versionCode 1
+ versionName "1.0"
+ testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+ }
+ buildTypes {
+ release {
+ minifyEnabled false
+ proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+ }
+ }
+}
+
+dependencies {
+ implementation fileTree(dir: 'libs', include: ['*.jar'])
+
+ implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
+
+ implementation 'androidx.core:core-ktx:1.0.2'
+ implementation 'androidx.appcompat:appcompat:1.0.2'
+ implementation 'androidx.cardview:cardview:1.0.0'
+ implementation 'androidx.recyclerview:recyclerview:1.0.0'
+ implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
+
+ implementation 'com.squareup.retrofit2:retrofit:2.6.1'
+ implementation 'com.squareup.retrofit2:converter-gson:2.6.1'
+
+ implementation 'com.google.code.gson:gson:2.8.5'
+
+ implementation 'com.jakewharton.timber:timber:4.7.1'
+
+ testImplementation 'junit:junit:4.12'
+ androidTestImplementation 'androidx.test:runner:1.2.0'
+ androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
+}
diff --git a/7weeks/app/proguard-rules.pro b/7weeks/app/proguard-rules.pro
new file mode 100644
index 0000000..f1b4245
--- /dev/null
+++ b/7weeks/app/proguard-rules.pro
@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+# http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+# public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile
diff --git a/7weeks/app/src/androidTest/java/io/cro/example/ExampleInstrumentedTest.kt b/7weeks/app/src/androidTest/java/io/cro/example/ExampleInstrumentedTest.kt
new file mode 100644
index 0000000..7bd42e9
--- /dev/null
+++ b/7weeks/app/src/androidTest/java/io/cro/example/ExampleInstrumentedTest.kt
@@ -0,0 +1,24 @@
+package io.cro.example
+
+import androidx.test.InstrumentationRegistry
+import androidx.test.runner.AndroidJUnit4
+
+import org.junit.Test
+import org.junit.runner.RunWith
+
+import org.junit.Assert.*
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+@RunWith(AndroidJUnit4::class)
+class ExampleInstrumentedTest {
+ @Test
+ fun useAppContext() {
+ // Context of the app under test.
+ val appContext = InstrumentationRegistry.getTargetContext()
+ assertEquals("io.cro.example", appContext.packageName)
+ }
+}
diff --git a/7weeks/app/src/main/AndroidManifest.xml b/7weeks/app/src/main/AndroidManifest.xml
new file mode 100644
index 0000000..eacd824
--- /dev/null
+++ b/7weeks/app/src/main/AndroidManifest.xml
@@ -0,0 +1,27 @@
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
\ No newline at end of file
diff --git a/7weeks/app/src/main/java/io/cro/example/ExampleApplication.kt b/7weeks/app/src/main/java/io/cro/example/ExampleApplication.kt
new file mode 100644
index 0000000..b9b0ceb
--- /dev/null
+++ b/7weeks/app/src/main/java/io/cro/example/ExampleApplication.kt
@@ -0,0 +1,11 @@
+package io.cro.example
+
+import android.app.Application
+import timber.log.Timber
+
+class ExampleApplication : Application() {
+ override fun onCreate() {
+ super.onCreate()
+ Timber.plant(Timber.DebugTree())
+ }
+}
\ No newline at end of file
diff --git a/7weeks/app/src/main/java/io/cro/example/LegacyActivity.kt b/7weeks/app/src/main/java/io/cro/example/LegacyActivity.kt
new file mode 100644
index 0000000..212e907
--- /dev/null
+++ b/7weeks/app/src/main/java/io/cro/example/LegacyActivity.kt
@@ -0,0 +1,69 @@
+package io.cro.example
+
+import android.os.AsyncTask
+import android.os.Bundle
+import androidx.appcompat.app.AppCompatActivity
+import androidx.recyclerview.widget.LinearLayoutManager
+import com.google.gson.Gson
+import com.google.gson.reflect.TypeToken
+import io.cro.example.adapter.UserAdapter
+import kotlinx.android.synthetic.main.activity_legacy.*
+import timber.log.Timber
+import java.net.HttpURLConnection
+import java.net.URL
+
+class LegacyActivity : AppCompatActivity() {
+ private val adapter: UserAdapter by lazy { UserAdapter() }
+ private val layoutManager: LinearLayoutManager by lazy { LinearLayoutManager(this) }
+
+ override fun onCreate(savedInstanceState: Bundle?) {
+ super.onCreate(savedInstanceState)
+ setContentView(R.layout.activity_legacy)
+ setupRecyclerView()
+ }
+
+ private fun setupRecyclerView() {
+ with(userList) {
+ adapter = this@LegacyActivity.adapter
+ layoutManager = this@LegacyActivity.layoutManager
+ }
+
+ NetworkTask(adapter).execute("https://api.github.com/users")
+ }
+}
+
+class NetworkTask(private val adapter: UserAdapter) : AsyncTask>() {
+ override fun doInBackground(vararg params: String?): List? {
+ val url = URL(params[0])
+ var users: List? = null
+
+ with(url.openConnection() as HttpURLConnection) {
+ requestMethod = "GET"
+ setRequestProperty("Accept", "application/vnd.github.v3+json")
+
+ inputStream.bufferedReader().use {
+ val stringBuffer = StringBuffer()
+ var inputLine = it.readLine()
+ while (!inputLine.isNullOrEmpty()) {
+ stringBuffer.append(inputLine)
+ inputLine = it.readLine()
+ }
+
+ users = Gson().fromJson(
+ stringBuffer.toString(),
+ object : TypeToken>() {}.type
+ )
+ }
+ }
+
+ return users
+ }
+
+ override fun onPostExecute(result: List?) {
+ super.onPostExecute(result)
+ Timber.d("LEGACY::USERS::$result")
+ result?.let {
+ adapter.updateItem(it)
+ }
+ }
+}
diff --git a/7weeks/app/src/main/java/io/cro/example/MainActivity.kt b/7weeks/app/src/main/java/io/cro/example/MainActivity.kt
new file mode 100644
index 0000000..3e72a46
--- /dev/null
+++ b/7weeks/app/src/main/java/io/cro/example/MainActivity.kt
@@ -0,0 +1,26 @@
+package io.cro.example
+
+import android.content.Intent
+import android.os.Bundle
+import androidx.appcompat.app.AppCompatActivity
+import kotlinx.android.synthetic.main.activity_main.*
+
+class MainActivity : AppCompatActivity() {
+
+ override fun onCreate(savedInstanceState: Bundle?) {
+ super.onCreate(savedInstanceState)
+ setContentView(R.layout.activity_main)
+
+ legacyButton.setOnClickListener {
+ Intent(this, LegacyActivity::class.java).apply {
+ startActivity(this)
+ }
+ }
+
+ retrofitButton.setOnClickListener {
+ Intent(this, RetrofitActivity::class.java).apply {
+ startActivity(this)
+ }
+ }
+ }
+}
diff --git a/7weeks/app/src/main/java/io/cro/example/RetrofitActivity.kt b/7weeks/app/src/main/java/io/cro/example/RetrofitActivity.kt
new file mode 100644
index 0000000..6130578
--- /dev/null
+++ b/7weeks/app/src/main/java/io/cro/example/RetrofitActivity.kt
@@ -0,0 +1,92 @@
+package io.cro.example
+
+import android.os.Bundle
+import androidx.appcompat.app.AppCompatActivity
+import androidx.recyclerview.widget.LinearLayoutManager
+import io.cro.example.adapter.UserAdapter
+import kotlinx.android.synthetic.main.activity_legacy.*
+import okhttp3.Interceptor
+import okhttp3.OkHttpClient
+import okhttp3.Response
+import retrofit2.Call
+import retrofit2.Callback
+import retrofit2.Retrofit
+import retrofit2.converter.gson.GsonConverterFactory
+import retrofit2.http.GET
+import timber.log.Timber
+import java.io.IOException
+
+class RetrofitActivity : AppCompatActivity() {
+ private val retrofit: Retrofit by lazy {
+ Retrofit.Builder()
+ .baseUrl("https://api.github.com/")
+ .client(
+ OkHttpClient.Builder()
+ .addInterceptor(HttpHeaderInterceptor())
+ .build()
+ )
+ .addConverterFactory(GsonConverterFactory.create())
+ .build()
+ }
+
+ private val adapter: UserAdapter by lazy { UserAdapter() }
+ private val layoutManager: LinearLayoutManager by lazy { LinearLayoutManager(this) }
+
+ override fun onCreate(savedInstanceState: Bundle?) {
+ super.onCreate(savedInstanceState)
+ setContentView(R.layout.activity_retrofit)
+ setupRecyclerView()
+ }
+
+ private fun setupRecyclerView() {
+ with(userList) {
+ adapter = this@RetrofitActivity.adapter
+ layoutManager = this@RetrofitActivity.layoutManager
+ }
+
+ getUsers()
+ }
+
+ private fun getUsers() {
+ retrofit.create(GitHubApi::class.java)
+ .getUsers().enqueue(object : Callback> {
+ override fun onResponse(
+ call: Call>,
+ response: retrofit2.Response>
+ ) {
+ if (response.isSuccessful) {
+ response.body()?.let {
+ adapter.updateItem(it)
+ }
+ }
+ }
+
+ override fun onFailure(call: Call>, t: Throwable) {
+ Timber.e("RETROFIT::onFailure::${t.message}")
+ }
+ })
+ }
+}
+
+class HttpHeaderInterceptor: Interceptor {
+ @Throws(IOException::class)
+ override fun intercept(chain: Interceptor.Chain): Response {
+ val request = chain.request()
+ val requestBuilder = request.newBuilder().apply {
+ addHeader("Accept", "application/vnd.github.v3+json")
+ }
+
+ return chain.proceed(requestBuilder.build())
+ }
+
+ companion object {
+ private enum class Headers(val key: String, val value: String) {
+ ACCEPT("Accept", "application/vnd.github.v3+json");
+ }
+ }
+}
+
+interface GitHubApi {
+ @GET("/users")
+ fun getUsers(): Call>
+}
diff --git a/7weeks/app/src/main/java/io/cro/example/UserProfile.kt b/7weeks/app/src/main/java/io/cro/example/UserProfile.kt
new file mode 100644
index 0000000..4b08be0
--- /dev/null
+++ b/7weeks/app/src/main/java/io/cro/example/UserProfile.kt
@@ -0,0 +1,68 @@
+package io.cro.example
+
+import com.google.gson.annotations.SerializedName
+
+data class UserProfile(
+ @SerializedName("login")
+ val login: String = "",
+ @SerializedName("id")
+ val id: Int = 0,
+ @SerializedName("node_id")
+ val nodeId: String = "",
+ @SerializedName("avatar_url")
+ val avatarUrl: String = "",
+ @SerializedName("gravatar_id")
+ val gravatarId: String = "",
+ @SerializedName("url")
+ val url: String = "",
+ @SerializedName("html_url")
+ val htmlUrl: String = "",
+ @SerializedName("followers_url")
+ val followersUrl: String = "",
+ @SerializedName("following_url")
+ val followingUrl: String = "",
+ @SerializedName("gists_url")
+ val gistsUrl: String = "",
+ @SerializedName("starred_url")
+ val starredUrl: String = "",
+ @SerializedName("subscriptions_url")
+ val subscriptionsUrl: String = "",
+ @SerializedName("organizations_url")
+ val organizationsUrl: String = "",
+ @SerializedName("repos_url")
+ val reposUrl: String = "",
+ @SerializedName("events_url")
+ val eventsUrl: String = "",
+ @SerializedName("received_events_url")
+ val receivedEventsUrl: String = "",
+ @SerializedName("type")
+ val type: String = "",
+ @SerializedName("site_admin")
+ val siteAdmin: Boolean = false,
+ @SerializedName("name")
+ val name: String = "",
+ @SerializedName("company")
+ val company: String = "",
+ @SerializedName("blog")
+ val blog: String = "",
+ @SerializedName("location")
+ val location: String = "",
+ @SerializedName("email")
+ val email: String = "",
+ @SerializedName("hireable")
+ val hireable: Boolean = false,
+ @SerializedName("bio")
+ val bio: String = "",
+ @SerializedName("public_repos")
+ val publicRepos: Int = 0,
+ @SerializedName("public_gists")
+ val publicGists: Int = 0,
+ @SerializedName("followers")
+ val followers: Int = 0,
+ @SerializedName("following")
+ val following: Int = 0,
+ @SerializedName("created_at")
+ val createdAt: String = "",
+ @SerializedName("updated_at")
+ val updatedAt: String = ""
+)
\ No newline at end of file
diff --git a/7weeks/app/src/main/java/io/cro/example/adapter/UserAdapter.kt b/7weeks/app/src/main/java/io/cro/example/adapter/UserAdapter.kt
new file mode 100644
index 0000000..d0906f5
--- /dev/null
+++ b/7weeks/app/src/main/java/io/cro/example/adapter/UserAdapter.kt
@@ -0,0 +1,34 @@
+package io.cro.example.adapter
+
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.recyclerview.widget.RecyclerView
+import io.cro.example.R
+import io.cro.example.UserProfile
+import kotlinx.android.extensions.LayoutContainer
+import kotlinx.android.synthetic.main.item_user.view.*
+
+class UserAdapter : RecyclerView.Adapter() {
+ private var dataSet = mutableListOf()
+
+ fun updateItem(dataSet: List) {
+ this.dataSet = dataSet as MutableList
+ notifyDataSetChanged()
+ }
+
+ override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): UserViewHolder =
+ UserViewHolder(LayoutInflater.from(parent.context).inflate(R.layout.item_user, parent, false))
+
+ override fun onBindViewHolder(holder: UserViewHolder, position: Int) {
+ holder.bindTo(dataSet[position])
+ }
+
+ override fun getItemCount(): Int = dataSet.size
+}
+
+class UserViewHolder(override val containerView: View) : RecyclerView.ViewHolder(containerView), LayoutContainer {
+ fun bindTo(data: UserProfile) {
+ itemView.nameTextView.text = data.login
+ }
+}
\ No newline at end of file
diff --git a/7weeks/app/src/main/res/drawable-v24/ic_launcher_foreground.xml b/7weeks/app/src/main/res/drawable-v24/ic_launcher_foreground.xml
new file mode 100644
index 0000000..1f6bb29
--- /dev/null
+++ b/7weeks/app/src/main/res/drawable-v24/ic_launcher_foreground.xml
@@ -0,0 +1,34 @@
+
+
+
+
+