Done!!! All Fully Functional

app/build.gradle

@@ -3,12 +3,12 @@ apply plugin: 'kotlin-android'
 apply plugin: 'kotlin-android-extensions'
 
 android {
-    compileSdkVersion 26
+    compileSdkVersion 25
     buildToolsVersion "25.0.2"
     defaultConfig {
         applicationId "com.codingblocks.restapiretrofitjson"
         minSdkVersion 16
-        targetSdkVersion 26
+        targetSdkVersion 25
         versionCode 1
         versionName "1.0"
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
@@ -27,13 +27,14 @@ dependencies {
         exclude group: 'com.android.support', module: 'support-annotations'
     })
     compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
-    compile 'com.android.support:appcompat-v7:26.+'
-    compile 'com.android.support:recyclerview-v7:26.+'
-    compile 'com.android.support:cardview-v7:26.+'
-    compile 'com.android.support.constraint:constraint-layout:1.0.0-alpha8'
+    compile 'com.android.support:appcompat-v7:25.+'
+    compile 'com.android.support:recyclerview-v7:25.+'
+    compile 'com.android.support:cardview-v7:25.+'
+    compile 'com.android.support.constraint:constraint-layout:1.0.2'
     compile 'com.squareup.retrofit2:retrofit:2.3.0'
     compile 'com.squareup.retrofit2:converter-gson:2.3.0'
     testCompile 'junit:junit:4.12'
+    implementation 'com.squareup.picasso:picasso:2.5.2'
 }
 repositories {
     mavenCentral()

app/src/main/AndroidManifest.xml

@@ -14,6 +14,9 @@
         <activity android:name=".activities.UsersActivity" />
         <activity android:name=".activities.PostsActivity" />
         <activity android:name=".activities.CommentsActivity" />
+        <activity android:name=".activities.AlbumActivity"/>
+        <activity android:name=".activities.PhotosActivity"/>
+        <activity android:name=".activities.ViewPhotoActivity"/>
         <activity android:name=".MainActivity">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />

app/src/main/java/com/codingblocks/restapiretrofitjson/MainActivity.kt

@@ -3,30 +3,31 @@ package com.codingblocks.restapiretrofitjson
 import android.content.Intent
 import android.support.v7.app.AppCompatActivity
 import android.os.Bundle
+import android.view.View
+import com.codingblocks.restapiretrofitjson.activities.AlbumActivity
 import com.codingblocks.restapiretrofitjson.activities.PostsActivity
 import com.codingblocks.restapiretrofitjson.activities.TodosActivity
 import com.codingblocks.restapiretrofitjson.activities.UsersActivity
 
 import kotlinx.android.synthetic.main.activity_main.*
 
-class MainActivity : AppCompatActivity() {
+class MainActivity : AppCompatActivity(), View.OnClickListener {
+    override fun onClick(v: View) {
+        when(v.id){
+            R.id.btnAlbums->startActivity(Intent(this@MainActivity,AlbumActivity::class.java))
+            R.id.btnPosts->startActivity(Intent(this@MainActivity,PostsActivity::class.java))
+            R.id.btnUsers->startActivity(Intent(this@MainActivity,UsersActivity::class.java))
+            R.id.btnTodos->startActivity(Intent(this@MainActivity,TodosActivity::class.java))
+        }
+    }
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
 
-        btnPosts.setOnClickListener({
-            startActivity(Intent(this@MainActivity, PostsActivity::class.java))
-        })
-
-        btnUsers.setOnClickListener({
-            startActivity(Intent(this@MainActivity, UsersActivity::class.java))
-        })
-
-        btnTodos.setOnClickListener({
-            startActivity(Intent(this@MainActivity, TodosActivity::class.java))
-        })
-
-
+        btnAlbums.setOnClickListener(this)
+        btnPosts.setOnClickListener(this)
+        btnUsers.setOnClickListener(this)
+        btnTodos.setOnClickListener(this)
     }
 }

app/src/main/java/com/codingblocks/restapiretrofitjson/activities/AlbumActivity.kt

@@ -0,0 +1,55 @@
+package com.codingblocks.restapiretrofitjson.activities
+
+import android.content.Intent
+import android.os.Bundle
+import android.support.v7.app.AppCompatActivity
+import android.support.v7.widget.LinearLayoutManager
+import android.view.View
+import com.codingblocks.restapiretrofitjson.R
+import com.codingblocks.restapiretrofitjson.adapters.AlbumsAdapter
+import com.codingblocks.restapiretrofitjson.api.API
+import com.codingblocks.restapiretrofitjson.interfaces.OnItemClickListener
+import com.codingblocks.restapiretrofitjson.models.Album
+import kotlinx.android.synthetic.main.activity_album.*
+import retrofit2.Call
+import retrofit2.Callback
+import retrofit2.Response
+import java.util.*
+
+class AlbumActivity : AppCompatActivity() {
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_album)
+
+        rvAlbumsView.layoutManager = LinearLayoutManager(this)
+        val albumsAdapter = AlbumsAdapter(ArrayList<Album>(), this)
+        rvAlbumsView.adapter = albumsAdapter
+        pbProgress.visibility = View.VISIBLE
+        btnShowAllPhotos.setOnClickListener { startActivity(Intent(this@AlbumActivity, PhotosActivity::class.java)) }
+        albumsAdapter.setOnItemClickListener(OnItemClickListener { itemid, view ->
+            val i = Intent(this@AlbumActivity, PhotosActivity::class.java)
+            i.putExtra("albumId", itemid)
+            startActivity(i)
+        })
+        val receivedId = intent.getIntExtra("userId", -1)
+        supportActionBar!!.title = "Albums"
+        val albumsApi = API.getInstance().albumsApi
+        val receiveAlbums = object : Callback<ArrayList<Album>> {
+            override fun onResponse(call: Call<ArrayList<Album>>, response: Response<ArrayList<Album>>) {
+                albumsAdapter.updateAlbums(response.body()!!, pbProgress)
+            }
+
+            override fun onFailure(call: Call<ArrayList<Album>>, t: Throwable) {
+
+            }
+        }
+
+        if (receivedId != -1) {
+            albumsApi.getAlbumsbyUserId(receivedId).enqueue(receiveAlbums)
+        } else {
+            albumsApi.getAlbumsbyUserId(null).enqueue(receiveAlbums)
+        }
+
+    }
+}

app/src/main/java/com/codingblocks/restapiretrofitjson/activities/CommentsActivity.kt

@@ -1,20 +1,17 @@
 package com.codingblocks.restapiretrofitjson.activities
 
-import android.support.v7.app.AppCompatActivity
 import android.os.Bundle
+import android.support.v7.app.AppCompatActivity
 import android.support.v7.widget.LinearLayoutManager
-
+import android.view.View
 import com.codingblocks.restapiretrofitjson.R
 import com.codingblocks.restapiretrofitjson.adapters.CommentAdapter
 import com.codingblocks.restapiretrofitjson.api.API
 import com.codingblocks.restapiretrofitjson.models.Comment
 import kotlinx.android.synthetic.main.activity_comments.*
-
-import kotlinx.android.synthetic.main.activity_comments.view.*
 import retrofit2.Call
 import retrofit2.Callback
 import retrofit2.Response
-import retrofit2.Retrofit
 
 class CommentsActivity : AppCompatActivity() {
 
@@ -25,6 +22,9 @@ class CommentsActivity : AppCompatActivity() {
         val commentAdapter =  CommentAdapter(this, ArrayList<Comment>())
         rvCommentsList.layoutManager = LinearLayoutManager(this)
         rvCommentsList.adapter = commentAdapter
+        pbProgress.visibility= View.VISIBLE
+
+        supportActionBar!!.title="Comments"
 
 
 
@@ -36,7 +36,7 @@ class CommentsActivity : AppCompatActivity() {
 
             override fun onResponse(call: Call<ArrayList<Comment>>?, response: Response<ArrayList<Comment>>?) {
                 //
-                commentAdapter.updateComments(response!!.body()!!)
+                commentAdapter.updateComments(response!!.body()!!,pbProgress)
             }
         })
     }

app/src/main/java/com/codingblocks/restapiretrofitjson/activities/PhotosActivity.kt

@@ -0,0 +1,58 @@
+package com.codingblocks.restapiretrofitjson.activities
+
+import android.content.Intent
+import android.os.Bundle
+import android.support.v7.app.AppCompatActivity
+import android.support.v7.widget.LinearLayoutManager
+import android.view.View
+import com.codingblocks.restapiretrofitjson.R
+import com.codingblocks.restapiretrofitjson.adapters.PhotosAdapter
+import com.codingblocks.restapiretrofitjson.api.API
+import com.codingblocks.restapiretrofitjson.interfaces.OnPhotoClickListener
+import com.codingblocks.restapiretrofitjson.models.Photos
+import kotlinx.android.synthetic.main.activity_photos.*
+import retrofit2.Call
+import retrofit2.Callback
+import retrofit2.Response
+import java.util.*
+
+class PhotosActivity : AppCompatActivity() {
+
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_photos)
+        rvPhotosView.layoutManager = LinearLayoutManager(this)
+        val photosAdapter = PhotosAdapter(ArrayList<Photos>(), this)
+        rvPhotosView.adapter = photosAdapter
+        pbProgress.visibility = View.VISIBLE
+
+        photosAdapter.setOnPhotoClickListener(OnPhotoClickListener { url, title ->
+            val i = Intent(this@PhotosActivity, ViewPhotoActivity::class.java)
+            i.putExtra("url", url)
+            i.putExtra("title", title)
+            startActivity(i)
+        })
+
+        val receivedId = intent.getIntExtra("albumId", -1)
+
+        supportActionBar!!.title = "Photos"
+
+        val photosApi = API.getInstance().photosApi
+
+        val receivePhotos = object : Callback<ArrayList<Photos>> {
+            override fun onResponse(call: Call<ArrayList<Photos>>, response: Response<ArrayList<Photos>>) {
+                photosAdapter.updateAlbums(response.body()!!, pbProgress)
+            }
+
+            override fun onFailure(call: Call<ArrayList<Photos>>, t: Throwable) {
+
+            }
+        }
+        if (receivedId != -1) {
+            photosApi.getPhotosOfAlbumId(receivedId).enqueue(receivePhotos)
+        } else {
+            photosApi.photos.enqueue(receivePhotos)
+        }
+    }
+}