How to Build PDF Downloader App in Android with Kotlin?
Last Updated :
31 Oct, 2022
If you are creating apps for students or for educational purposes then you need to add some PDF files for displaying some data inside our app. These PDF files are updated on regular basis. A sample video is given below to get an idea about what we are going to do in this article.
In this article, we will build an application to help users download notes in pdf format.
Step by Step Implementation
Step 1: Create a New Project in Android Studio
To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. Note that select Kotlin as the programming language.
Step 2: Add Internet Permission in the AndroidManifest.xml file
XML
<uses-permission android:name="android.permission.INTERNET"/>
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Step 3: Create Firebase Project
Although we are not connecting firebase with the android studio we will be using it as a medium of storage. Go to the firebase website and click go to console and create a new firebase project. After that go to firebase storage here you will get the option to upload pdf files click on that upload button in order to upload files from your system. Click on the pdf uploaded by you in order to generate a pdf URL like this.
Step 4: Design layout Files
Navigate to the app > res > layout > activity_main.xml and add the below code to that file. In activity_min.xml we are just adding a RecyclerView. Below is the code for the activity_main.xml file. Comments are added inside the code to understand the code in more detail.
XML
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
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Since we are using recycler view we need to create a new layout file for that go to res->layout and create a new Layout resource file named item_layout.
item_layout file
XML
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:layout_margin="5dp">
<ImageView
android:id="@+id/pdf_image"
android:layout_width="96dp"
android:layout_height="96dp"
android:src="@drawable/pdf"/>
<TextView
android:id="@+id/subj_name"
android:layout_width="match_parent"
android:layout_height= "match_parent"
android:text="System Design Notes"
android:textSize="20sp"
android:textAlignment="center"
android:padding="30dp"
android:textStyle="bold"
android:textColor="@color/black">
</TextView>
</LinearLayout>
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Step 5: Create Notes class
Kotlin
class Notes
( var image : Int
, var subj_name : String
,var url : String?
)
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Step 6: Create NotesAdapter class
Since we are using recycler view therefore we will create an adapter class. We will also use the concept of Download Manager in order to download notes in pdf format.
Kotlin
class NotesAdapter( var data: ArrayList<Notes>, var context: Context) : RecyclerView.Adapter<NotesAdapter.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val layout = LayoutInflater.from(context).inflate(R.layout.item_layout, parent, false)
return ViewHolder(layout)
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.name.text = data[position].subj_name
holder.image.setImageResource(data[position].image)
holder.itemView.setOnClickListener{
var download= context.getSystemService(Context.DOWNLOAD_SERVICE) as DownloadManager
var PdfUri = Uri.parse(data[position].url)
var getPdf = DownloadManager.Request(PdfUri)
getPdf.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED)
download.enqueue(getPdf)
Toast.makeText(context,"Download Started", Toast.LENGTH_LONG).show()
}
}
override fun getItemCount(): Int {
return data.size
}
inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
internal val name: TextView
internal val image: ImageView
init {
name = itemView.findViewById(R.id.subj_name)
image = itemView.findViewById(R.id.pdf_image)
}
}
}
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Step 7: Working with the MainActivity.kt file
Go to the MainActivity.kt file and refer to the following code. Below is the code for the MainActivity.kt file. Comments are added inside the code to understand the code in more detail.
Kotlin
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val item = ArrayList<Notes>()
item.add(
Notes(
R.drawable.pdf,
"System Design",
)
)
item.add(
Notes(
R.drawable.pdf,
"DBMS",
)
)
item.add(
Notes(
R.drawable.pdf,
"C Notes",
)
)
item.add(
Notes(
R.drawable.pdf,
"Resume",
)
)
val recycler_view = findViewById<RecyclerView>(R.id.recycler_view)
recycler_view.layoutManager = LinearLayoutManager(applicationContext)
val adapter = NotesAdapter(item,this)
recycler_view.adapter = adapter
}
}
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Output:
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