i am generating pdf from recyclerView , but empty pdf is generated.Android Studio - android-recyclerview

Question

i am generating pdf from recycler view, but getting empty pdf, probably recycler view is not getting converted to bitmap.
please help.
i have atttached the files here
the recycler view is properly shown but when pdf is generated , blank pdf is generated.
MainActivity.java
package com.example.recyclerview;
public class MainActivity extends AppCompatActivity {
// ArrayList for person names
ArrayList langNames = new ArrayList<>(Arrays.asList("Person 1", "Person 2", "Person 3", "Person 4", "Person 5", "Person 6", "Person 7","Person 8", "Person 9", "Person 10", "Person 11", "Person 12", "Person 13", "Person 14"));
ArrayList langText= new ArrayList<>(Arrays.asList("Person 1", "Person 2", "Person 3", "Person 4", "Person 5", "Person 6", "Person 7","Person 8", "Person 9", "Person 10", "Person 11", "Person 12", "Person 13", "Person 14"));
private Button btn;
private LinearLayout linear;
private Bitmap bitmap;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// get the reference of RecyclerView
RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
// set a LinearLayoutManager with default horizontal orientation and false value for reverseLayout to show the items from start to end
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getApplicationContext(),LinearLayoutManager.VERTICAL,false);
recyclerView.setLayoutManager(linearLayoutManager);
// call the constructor of CustomAdapter to send the reference and data to Adapter
PDFadapter adapter = new PDFadapter(MainActivity.this, langNames,langText);
recyclerView.setAdapter(adapter); // set the Adapter to RecyclerView
linear=findViewById(R.id.linear);
btn=findViewById(R.id.btn1);
btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Log.d("size"," "+linear.getWidth()+" "+linear.getHeight());
bitmap=loadBitmap(adapter,linear.getWidth(),linear.getHeight());
try {
createPdf();
} catch (IOException e) {
e.printStackTrace();
}
}
});
// pdfConverter.createPdf((Context)MainActivity.this, (Activity)MainActivity.this);
}
private Bitmap loadBitmap(LinearLayout linear, int width, int height) {
Bitmap bitmap=Bitmap.createBitmap(width,height,Bitmap.Config.ARGB_8888);
Canvas canvas =new Canvas(bitmap);
linear.draw(canvas);
return bitmap;
}
private void createPdf() throws IOException {
WindowManager windowManager=(WindowManager)getSystemService(Context.WINDOW_SERVICE);
DisplayMetrics dispalyMetrics=new DisplayMetrics();
this.getWindowManager().getDefaultDisplay().getMetrics(dispalyMetrics);
float width=dispalyMetrics.widthPixels;
float height=dispalyMetrics.heightPixels;
int convertwidth=(int)width;
int converthieght=(int)height;
PdfDocument document = new PdfDocument();
PdfDocument.PageInfo pageInfo=new PdfDocument.PageInfo.Builder(convertwidth,converthieght,1).create();
PdfDocument.Page page= document.startPage(pageInfo);
Canvas canvas= page.getCanvas();
Paint paint=new Paint();
canvas.drawPaint(paint);
bitmap=Bitmap.createScaledBitmap(bitmap,convertwidth,converthieght,true);
canvas.drawBitmap(bitmap,0,0,null);
document.finishPage(page);
File file=new File(getApplicationContext().getFilesDir(),"/abcd.pdf");
document.writeTo(new FileOutputStream(file));
document.close();
}
}
PDFadapter.java
public class PDFadapter extends RecyclerView.Adapter<PDFadapter.MyViewHolder> {
ArrayList langNames;
ArrayList langText;
Context context;
public PDFadapter(Context context, ArrayList langNames, ArrayList langText) {
this.context = context;
this.langNames = langNames;
this.langText= langText;
}
#Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
// infalte the item Layout
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.layout, parent, false);
// set the view's size, margins, paddings and layout parameters
MyViewHolder vh = new MyViewHolder(v); // pass the view to View Holder
return vh;
}
#Override
public void onBindViewHolder(MyViewHolder holder, final int position) {
// set the data in items
holder.name.setText((String) langNames.get(position));
holder.text.setText((String) langText.get(position));
// implement setOnClickListener event on item view.
}
#Override
public int getItemCount() {
return langNames.size();
}
public class MyViewHolder extends RecyclerView.ViewHolder {
// init the item view's
TextView name;
TextView text;
public MyViewHolder(View itemView) {
super(itemView);
// get the reference of item view's
name = (TextView) itemView.findViewById(R.id.name);
text = (TextView) itemView.findViewById(R.id.texts);
}
}
}
layout.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/linearlayout"
android:orientation="vertical">
<!--
items for a single row of RecyclerView
-->
<TextView
android:id="#+id/name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:textColor="#color/black"
android:textSize="25sp" />
<TextView
android:id="#+id/texts"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:textColor="#color/black"
android:textSize="18sp" />
</LinearLayout>
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
android:orientation="vertical">
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/btn1"
/>
<LinearLayout
android:layout_width="match_parent"
android:id="#+id/linear"
android:orientation="vertical"
android:layout_height="match_parent">
<androidx.recyclerview.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/recyclerView"
tools:context=".MainActivity"
/>
</LinearLayout>
</LinearLayout>
blank pdf generated