[wooki & 스타크] Kotlin Coroutine을 활용해서 동시에 여러 이미지를 다운로드 받아서 표시 및 PR 피드백 적용

app/build.gradle

@@ -37,6 +37,8 @@ android {
 
 dependencies {
 
+    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.5.1'
+    implementation 'com.google.code.gson:gson:2.8.6'
     implementation 'androidx.coordinatorlayout:coordinatorlayout:1.2.0'
     implementation 'androidx.core:core-ktx:1.7.0'
     implementation 'androidx.appcompat:appcompat:1.4.1'

app/src/main/AndroidManifest.xml

@@ -6,6 +6,7 @@
 
     <uses-permission-sdk-23 android:name="android.permission.READ_EXTERNAL_STORAGE" />
     <uses-permission-sdk-23 android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
+    <uses-permission-sdk-23 android:name="android.permission.INTERNET"/>
 
     <application
         android:allowBackup="true"

app/src/main/assets/json/doodle.json

@@ -0,0 +1 @@
+[{"title":"1","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSmETnjE9_LGsbWjeNCwlRJ4Ox1ioqxEVtWd7Z4QCKHtI7PewxvEg","date":"20140116"}, {"title":"2","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcS4XFa0i2H58farLmNpuChYmuADmvu3_dgE6aetcAmxhPAacH-32w","date":"20140505"}, {"title":"3","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcSxGkUwR3FlXBWZPSTCoXXaZaalUP0RM8N8WicExXqnOtJwY6Jzcg","date":"20131212"}, {"title":"4","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcQSmurpXwTAlcZI_9f51yyGCcFjN3AkD0lcrKqQtB4ImZeJKth9","date":"20130301"}, {"title":"5","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcSXKmAjYqJ10aoTvnt-LCLadn5f1EgivzvGKFlrMuIWVYigkA4Sng","date":"20140101"}, {"title":"6","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcRtW0Zacno8gtEc__OY43Hev7cWHHQDQi3dPFm4c5WHeTZXN2eP","date":"20130707"}, {"title":"7","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQ2lawOADm7fF6lD646xkmsYrIyU9taOcjBhzgZM-RxvZBeZrOA4g","date":"20130815"}, {"title":"8","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcS_pqRqREvuN0pDqTkxEsxF--p2d-3c0TY4ATKJust15pYRQyc8","date":"20131231"}, {"title":"9","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcTqXCdyNDzE1MkQdjwgfF-Aaa3drzaTDF2QfAMp1ng1K4EOB_7g","date":"20131231"}, {"title":"10","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcTFXjFTFfPTnQ4_ZZ7tiNQpsZZarA4bKN1uZD5jjJe4PWo-il_Rqg","date":"20131231"}, {"title":"11","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcSdbC0qirFudH3vOV-PZJXGt7HwraYyu9FmEg8AUxVN6I4xBLrU","date":"20131231"}, {"title":"12","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQy-7Qxk6eVWLWfX2KQF_DEefudH5QYIMypgwW8UtGGVP3uVluM","date":"20131231"}, {"title":"13","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQl9wwfGV5ARot19gI61DNtO5XC27p3Bq0XYxekQUy1g326gaGC","date":"20131231"}, {"title":"14","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRG83EQqTiO-YxkSnqO03r912wpBhmlqC8ZZbG75HDZnQx_PKOF","date":"20131231"}, {"title":"15","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcSHUQomYApnFdxplcbsZBSc_RR97g39rAes37dExgQC7pZIpxJELA","date":"20131231"}, {"title":"16","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcRH5wwN7CPN6ZJ-_66vKtZ6qlUtD6hSos-7RR7RUD89M_KFcWAZMw","date":"20131231"}, {"title":"17","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcR9Cd66Wb4-FUqhspFXtrm71ERX1noi13QZwov0rG4e7koj8YiA","date":"20131231"}, {"title":"18","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcRmcohlLiSTq9X3NweCo8nPrpXJVj5GJVm2ufGLyAOjnk1Xl_HG","date":"20131231"}, {"title":"19","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcTn77jWNnFDAnm09-usD5F6jFTFSAbvgYDKCDv5A6bXzcxDw0eO","date":"20131231"}, {"title":"20","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcQWtYdQ1WiswubAIC_ziuo5Mu3pkM_l93RDQRl4K9slbxijAXU17A","date":"20131231"}, {"title":"21","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcRHdQ8lLY4qdRXUQh44fxCekzy0xu75v0LmaDbBHLItuJYfkf8WRA","date":"20131231"}, {"title":"22","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcR0p69KnQLBf0ehuYKqs7jUSJq3gvc62hVEExJDiOBq88iBDyTC","date":"20131231"}, {"title":"23","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcSdyJF2SRbjsM80iMTbmsDsEoe6KUfr074DJK2aw-80sRV_R0xa","date":"20131231"}, {"title":"24","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRTlJNv0t1d9n053adTCWl53Jyso82Kj2gUIkz0ZKy0iKLGgknD","date":"20131231"}, {"title":"25","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcQRvC3j6TSsOV7MNHCCj_Ikna1kzCuLrCy-jZGop4rE5ZioTi_p","date":"20131231"}, {"title":"26","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcTvkn-ICa5MDD3S3iJg9GW0DoMy-OmMiKXFp6KYlNxhYMeCZXVC","date":"20131231"}, {"title":"27","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcRxE7neFepNYSe2t97xOz0yVYhyd4z5NCJsAiljb2gJUCJbIeQH","date":"20131231"}, {"title":"28","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcSFbJX5rwnPib-wTpxEJOvHNGva8WEjlm3lW_3Qy-78vJnA7vfDoA","date":"20131231"}, {"title":"29","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRhnvz4IZOwSwV4pv8gEf5P-pD31ghpPL2IzdlEtv_JhwisdN2r","date":"20131231"}, {"title":"30","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcQHY2lek2ApQM20FwHA2vsGm3D6e50BJObFMeBio_PZzBWsV3oUxw","date":"20131231"}, {"title":"31","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcTSUO0C_lm8CHqxIfuboIN9msMp_ZbOCDAA27sjiu02XvFxrM52yw","date":"20131231"}, {"title":"32","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSE5JnFn64dKEXG0mhtJaC04fgD81Dvb_GZPAE5v8K62wBC_FLoQQ","date":"20131231"}, {"title":"33","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcTeCe5ZNXqA9g7o82p5fY3Jh0HBBOLaU-FQFYAAo0xiuMBu0xB56Q","date":"20131231"}, {"title":"34","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcTwB4yeCcexu228SqgJF8qF1pNUBApXopgQAYpyVPOgVyJvlEP-ng","date":"20131231"}, {"title":"35","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRUdmWMCaTUhWsW2l4M-s3EbDRwXGgPZdUR2HUqv9AWJrtHcWKlDw","date":"20131231"}, {"title":"36","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcRzIoSUokH0DnZRbhkyT4-JbNY440nTIcG2AkYvU_WX-kcHz721Jg","date":"20131231"}, {"title":"37","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcTC06hRpORcqgi-jRhQLP6zKdo-WACAvFqJYoPbvP39YExnzuayDA","date":"20131231"}, {"title":"38","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcT9hpPOAbmGv6po02Z8Iy1hJrKiOD7kihyUD-kdAifMmsqLsN-C","date":"20131231"}, {"title":"39","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcSzpfrsYAav1JekCPaIPQ3QjQN2k8z0hbeuX4pocSVSXuiLwQAZ","date":"20131231"}, {"title":"40","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcRN-slhQe-5XRnQokAKzCmNDWGaQBX_NYZte45vvn2WrmNQiBqx","date":"20131231"}, {"title":"41","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTaN5J6ZhpkNla438pJptzcL4sm8Ju4NAtmtLC1YTbwrBobWFRm","date":"20131231"}, {"title":"42","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcTB_ZNLOYTqvVwfwWly0n9GWlpF1V1h9W_tVvPZzNBDrRnJ3aeg1g","date":"20131231"}, {"title":"43","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcQjdEz_dIaby3LYeCOlClpA2bjLjdEIRdcZ3QXN_Rc76c8eeJ4F","date":"20131231"}, {"title":"44","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQSx3acD6YdUU3BFfom3wt3U9pQbmlNsMuzaT3w7z1Ny1SDJRID","date":"20131231"}, {"title":"45","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcRCbEA2-fQ_OihfJ3ok_WI-tUuGVg3jbp_pvsauHOx41GLdJyilDg","date":"20131231"}, {"title":"46","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQT4XieOuJCmXGda9OfhdwofFVesR2EZ717WQlofsp-s8IwprHe","date":"20131231"}, {"title":"47","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcQBeq4KyzmzJiEVUhBiIVSNwQ1OT7r9xWgbECZeGiOl6BhWZW7S","date":"20131231"}, {"title":"48","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcTL5Ig1vtLap9XviLDbAItCc6w7LYnOP6ZtuTLOslYcp1VJwxOnQg","date":"20131231"}, {"title":"49","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcTMCDzzJshLwCe9bWATULycI8qoHuwvC0w4Ge8RcFwhzxf70qdZFw","date":"20131231"}, {"title":"50","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcQHsXdMPGl0Pxpoti7bkNTsR3-kPlHMMRVvV6A7GvzpH6P2MDW1","date":"20131231"}, {"title":"51","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcT_t5DoBUz4RI92HUeIqHctYhMH-penRAXFKKW7CI1FqZkQTSpLlg","date":"20131231"}, {"title":"52","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcShEvspSDZSC24KnKXOAIJOpuWaRxcT0XIX0PtpDa8ivaY0IGHY","date":"20131231"}, {"title":"53","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcSriFKKXwrDU8_VTQ2kZsQftB8tUGdCgo8CqjuE7O64S6Bxai9n","date":"20131231"}, {"title":"54","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcSAu6HkU6UyG5cxKLbEuusP3ub_GzeSlXiMlk8Uh-2qJXSrPkeG","date":"20131231"}, {"title":"55","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcSI6Ynhd3Cg2ByDGi5vF8v-HbJurJvnP8AAajxeTDXAFg-pFgo_","date":"20131231"}, {"title":"56","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcQkYRww3YPsZ_Nc0L3opCxqe0pHJKpdInIUCCYMyr_OzMam5LLN","date":"20131231"}, {"title":"57","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcTcHnCT_v48m5NA3E3kabPy1ZZCidbjh8KnWp4ibNPkJ9JVkeibrg","date":"20131231"}, {"title":"58","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSH4wCYUcNRemDzL_6t2Tv7F6i8wOWFgUxhNrW2coxZ2utp4_AH","date":"20131231"}, {"title":"59","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcQSxJuiNbJnl3wOaPvJadz1jd8ctTFhRKYxrFLd99GXdG6yN_sbJw","date":"20131231"}, {"title":"60","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSU4UhLouHDYJgKIqtYWC3O8HOEzqs8PeYRNE3F-kV8lZe0Ch-xIQ","date":"20131231"}, {"title":"61","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcQkYtV9uZuJgWI1mq-MMKOf1EihHP_QtPhbBetodSuvD-lHLFBFtA","date":"20131231"}, {"title":"62","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcRxydues49j-6-vZeI6-1mrLF9QRFWb1hhviOFGw1IWrfSv9nyMpw","date":"20131231"}, {"title":"63","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQAMQ7UjgAIA5Brz5j9BRz2drt534T6OCpHK9yIFJgA19p7qybXug","date":"20131231"}, {"title":"64","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcS8J7LNobRDgEX66GMsQBLzBrHj5l_-rHZ_Cf2OuI8pY-FICAFM-A","date":"20131231"}, {"title":"65","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcS2gMlIIi2dyW6AX-lm3HKDjWXitTu3I9O346yuvcsQ7lcGsB4M","date":"20131231"}, {"title":"66","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcTAspnGxEhA1i9JVJcfAfM7BQC_1Xwm9BlARzV2XYAJizqTBf2s","date":"20131231"}, {"title":"67","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcQxTAqX9udeDvv_sEoiECAN2tHxmGZBdMw89ebpJtgpVF-zJrO_","date":"20131231"}, {"title":"68","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQ_Y8RuqlxhKeasC90RBbfflR_J4RTcQv_TVd3I1DzdWy_4tfZc4w","date":"20131231"}, {"title":"69","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcQPo-aYYTRys4365PlQKxhgAaotsHZ74lwc3SryBYMuq6eQCiDK","date":"20131231"}, {"title":"70","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSx5_02SuLgcMjWHg7vUH54TmSYrNcsqtTkz6_Q_iNC8aTXBJdtbQ","date":"20131231"}, {"title":"71","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcR-32Ge8DaAq_81IBLPFdRWmKVYgvN9YyDKKjXh6CTTpgey8qbC","date":"20131231"}, {"title":"72","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQsR0CwZv4wDO8TqaXdoGOf82NjLorANkZhDHr79uy8sluT5SIA","date":"20131231"}, {"title":"73","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcQv5CdOLsDVXHPt0aPYssvFJsTZPm6QvakDWks0UHk3gZp6mfWi","date":"20131231"}, {"title":"74","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcSn6Zwy25E-2DuSpZc_dWloNo4c8HpYyW9mOw3JxfOeQmwko_mM","date":"20131231"}, {"title":"75","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcRyBtBFP9pmU7nN6_66G5FM-nGGZ1WLQqeu6UVYa1FWV6q19-9hrg","date":"20131231"}, {"title":"76","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcSOqfZRjije6RTmuMoDA8RoNNcgHIX2Q8PPxERjCYlmPJkNb6ckYA","date":"20131231"}, {"title":"77","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcSy1zR1n7W2FAJZ7Ha6njgnGt6B0ThCKCjFchKa1QQ95cRqFfXqJA","date":"20131231"}, {"title":"78","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSE3wiy5sFv_slOmU5PRHn438Ajz6Ujb6MeUXImrjlqsX6SRGmvCQ","date":"20131231"}, {"title":"79","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcR8bsrnVDlJvvl_XPP7GHlREoLYXlJ1vIqXehVuk9algQ7SwZrP","date":"20131231"}, {"title":"80","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcT24KfqNqeWnGFhyfxeJ1IGqgQ08iIHLwwR1JqrPpxKqLcH-pHW-A","date":"20131231"}, {"title":"81","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcRid3rnrk8mWwTpHvVEwC0C4wqm2xgxgSpjA8Hw6V3uTKDanD7YHg","date":"20131231"}, {"title":"82","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcSzP5Lg7qiaePd8ZMIF2iKvX4Q9LPv9ekKBMJWTybDTErpzm3g7","date":"20131231"}, {"title":"83","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTtPmAoNoaSoLhH_nQUAp3Ahx7C8pFAGVPVv4vxyglDZ6cTngsJ6A","date":"20131231"}, {"title":"84","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcTWOlYBBxlSL1MymCtDr6Rmz9uvjgcrgOrVek7-kfO2gWDgwSCzvA","date":"20131231"}, {"title":"85","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTmjRwtmBAcygfwoExImHNbPt331wVue11AkzEfbMljMBliWsct","date":"20131231"}, {"title":"86","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcQqK_3JW9IN7xXsk2Q8EaIiAsSXASa39-stQXCYfMsYWKsMKW__","date":"20131231"}, {"title":"87","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcTFSBT5wGCP2nELjiJ7_PuWTPJkBhiCsfGSy08u9CvXm8KP53Co","date":"20131231"}, {"title":"88","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcTi-AHWOIeFNeP2UbUzTxeFhoe4zUPgm3sIzk9-enC3ZBGtbwWEDw","date":"20131231"}, {"title":"89","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcRcQs3fSDKHBoUopF8lixbGX1UxF6r0r4vvf5ueR59KVwaO1HkJRg","date":"20131231"}, {"title":"90","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcREzwa-g37RgGch9SoJijzXLV9BDb2wU6kBipZe_IBUUv6nzfmo","date":"20131231"}, {"title":"91","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcQzf1Qd-lsgoa-jHmt823aSScuzJ2eSFtknL_pCWfXflDGsEHuLPg","date":"20131231"}, {"title":"92","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcQ6ALiWHsrNXkpwrHWgDxnsiAUC53r7qMrTjLjgX5GiemyBvIXt7g","date":"20131231"}, {"title":"93","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcShE0ZWE1qc3C6mVpSPZqgnM1ekrEZfN2RwQSLUaAah1x2iP9Ld","date":"20131231"}, {"title":"94","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcQmPzP1osa37iZ1wfmRvLzIbZpVu5KYMDt_m5fmNLoFgkku2c5D","date":"20131231"}, {"title":"95","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcTh9uooRiwGK_BnDayQhb1Cl1IiAWbm83dss_-Po5jbfqxvlb1jeg","date":"20131231"}, {"title":"96","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSdkUKx54RL3zeZSV5mby8j9d2jTGxfM4fCFPXOXLG_4UWFN5uo","date":"20131231"}, {"title":"97","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRkZ5ypvsDxvVmPWgmeYkMa-hOtwGlmrZHINtWT19lIE2wBKUdULA","date":"20131231"}, {"title":"98","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTUHsB1dLviCTyGRL2eF5uB6euYO6-bTEqozfRMvYfuzCI0eF5Tbw","date":"20131231"}, {"title":"99","image":"https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcSrZbv-CwVayjiPGeJdJGvJy7oX0ZosNOmQaNAXlZDJIKq9nSjOKw","date":"20131231"}, {"title":"100","image":"https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcTyaJ_r88ssQXi4fkjlHQ2JiAvsKsDBTS60H4ztBY3qvthy_dPrkA","date":"20131231"}, {"title":"101","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQveqpgIYrgTeR0q_D_Bma7tH5Odoy6j3tQg57_woJSqZlKsUMAiQ","date":"20131231"}, {"title":"102","image":"https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTawvbYEf8G0sIojF2tHeWJdwML03-03Ucm9AugXl3meHFVRz3U","date":"20131231"}, {"title":"103","image":"https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcS45OkAxOLL0niDKceEgiHZ8QI1p3FfGRSxtMeBHM1fKikwwtZLUw","date":"20140102"}]

app/src/main/java/com/example/photos/PhotoActivity.kt

@@ -36,8 +36,10 @@ class PhotoActivity : AppCompatActivity() {
                         Snackbar.make(binding.root, "앱을 이용하려면 권한이 필요합니다", Snackbar.LENGTH_SHORT).show()
                     }
                     else -> {
-                        Snackbar.make(binding.root, "권한이 없습니다.", Snackbar.LENGTH_SHORT).show()
-                        openSetting()
+                        Snackbar.make(binding.root, "권한이 없습니다.", Snackbar.LENGTH_SHORT)
+                            .setAction("설정") {
+                                openSetting()
+                            }.show()
                     }
                 }
             }

app/src/main/java/com/example/photos/RecyclerAdapter.kt

@@ -1,15 +1,14 @@
 package com.example.photos
 
 import android.view.LayoutInflater
-import android.view.View
 import android.view.ViewGroup
 import android.widget.ImageView
 import androidx.recyclerview.widget.RecyclerView
 import com.example.photos.databinding.ColorSquareBinding
 
 class RecyclerAdapter(private var dataset: MutableList<Int>) : RecyclerView.Adapter<RecyclerAdapter.ViewHolder>() {
 
-    inner class ViewHolder(binding: ColorSquareBinding) : RecyclerView.ViewHolder(binding.root) {
+    class ViewHolder(binding: ColorSquareBinding) : RecyclerView.ViewHolder(binding.root) {
         val imageView: ImageView = binding.imageView
     }
 

app/src/main/java/com/example/photos/step3/gallery/DoodleAdapter.kt

@@ -0,0 +1,50 @@
+package com.example.photos.step3.gallery
+
+import android.graphics.Bitmap
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import android.widget.ImageView
+import androidx.recyclerview.widget.DiffUtil
+import androidx.recyclerview.widget.ListAdapter
+import androidx.recyclerview.widget.RecyclerView
+import com.example.photos.R
+import com.example.photos.databinding.DoodleSquareBinding
+import com.example.photos.step3.model.DoodleImage
+
+class DoodleAdapter :
+    ListAdapter<DoodleImage, DoodleAdapter.DoodleViewHolder>(MyDoodleDiffCallback) {
+
+    class DoodleViewHolder(binding: DoodleSquareBinding) : RecyclerView.ViewHolder(binding.root) {
+        private val imageView: ImageView = binding.doodleImageView
+
+        fun bind(bitmap: Bitmap) {
+            imageView.setImageBitmap(null)
+            imageView.scaleType = ImageView.ScaleType.CENTER_CROP
+            imageView.setImageBitmap(bitmap)
+        }
+    }
+
+    override fun onCreateViewHolder(
+        parent: ViewGroup,
+        viewType: Int
+    ): DoodleViewHolder {
+        val binding = DoodleSquareBinding.inflate(LayoutInflater.from(parent.context), parent, false)
+        return DoodleViewHolder(binding)
+    }
+
+    override fun onBindViewHolder(holder: DoodleViewHolder, position: Int) {
+        val item = getItem(position)
+        holder.bind(item.bitmap)
+    }
+}
+
+object MyDoodleDiffCallback : DiffUtil.ItemCallback<DoodleImage>() {
+    override fun areItemsTheSame(oldItem: DoodleImage, newItem: DoodleImage): Boolean {
+        return oldItem.id == newItem.id
+    }
+
+    override fun areContentsTheSame(oldItem: DoodleImage, newItem: DoodleImage): Boolean {
+        return oldItem == newItem
+    }
+}