So apparently the code I was using wasn't compatible with android, hence the error I was getting. Below you'll find the correct code that actually works right (for creating a pdf file, putting some content in it, saving in and the opening the newly created file):

PS: For this you'll need to add the jar of iTextG to your project:

// Method for creating a pdf file from text, saving it then opening it for display
    public void createandDisplayPdf(String text) {
        
        Document doc = new Document();

        try {
            String path = Environment.getExternalStorageDirectory().getAbsolutePath() + "/Dir";

            File dir = new File(path);
            if(!dir.exists())
                dir.mkdirs();

            File file = new File(dir, "newFile.pdf");
            FileOutputStream fOut = new FileOutputStream(file);

            PdfWriter.getInstance(doc, fOut);

            //open the document
            doc.open();

            Paragraph p1 = new Paragraph(text);
            Font paraFont= new Font(Font.COURIER);
            p1.setAlignment(Paragraph.ALIGN_CENTER);
            p1.setFont(paraFont);

            //add paragraph to document
            doc.add(p1);    

        } catch (DocumentException de) {
            Log.e("PDFCreator", "DocumentException:" + de);
        } catch (IOException e) {
            Log.e("PDFCreator", "ioException:" + e);
        }
        finally {
            doc.close();
        }

        viewPdf("newFile.pdf", "Dir");
    }

    // Method for opening a pdf file
    private void viewPdf(String file, String directory) {

        File pdfFile = new File(Environment.getExternalStorageDirectory() + "/" + directory + "/" + file);
        Uri path = Uri.fromFile(pdfFile);

        // Setting the intent for pdf reader
        Intent pdfIntent = new Intent(Intent.ACTION_VIEW);
        pdfIntent.setDataAndType(path, "application/pdf");
        pdfIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

        try {
            startActivity(pdfIntent);
        } catch (ActivityNotFoundException e) {
            Toast.makeText(TableActivity.this, "No application has been found to open PDF files.", Toast.LENGTH_SHORT).show();
        }
    }

Do it this way:

import com.cete.dynamicpdf.*;
import com.cete.dynamicpdf.pageelements.Label;

import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.widget.Toast;

public class DynamicPDFHelloWorld extends Activity {
    private static String FILE = Environment.getExternalStorageDirectory()
            + "/HelloWorld.pdf";

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // Create a document and set it's properties
        Document objDocument = new Document();
        objDocument.setCreator("DynamicPDFHelloWorld.java");
        objDocument.setAuthor("Your Name");
        objDocument.setTitle("Hello World");

        // Create a page to add to the document
        Page objPage = new Page(PageSize.LETTER, PageOrientation.PORTRAIT,
                54.0f);

        // Create a Label to add to the page
        String strText = "Hello World...\nFrom DynamicPDF Generator "
                + "for Java\nDynamicPDF.com";
        Label objLabel = new Label(strText, 0, 0, 504, 100,
                Font.getHelvetica(), 18, TextAlign.CENTER);

        // Add label to page
        objPage.getElements().add(objLabel);

        // Add page to document
        objDocument.getPages().add(objPage);

        try {
            // Outputs the document to file
            objDocument.draw(FILE);
            Toast.makeText(this, "File has been written to :" + FILE,
                    Toast.LENGTH_LONG).show();
        } catch (Exception e) {
            Toast.makeText(this,
                    "Error, unable to write to file\n" + e.getMessage(),
                    Toast.LENGTH_LONG).show();
        }
    }
}

Also check these links. They will help you to fulfill your requirement.

1. http://www.dynamicpdf.com/Blog/post/2012/06/15/Generating-PDFs-Dynamically-on-Android.aspx

2. https://github.com/JoanZapata/android-pdfview

3. How to create PDFs in an Android app?

4. Render a PDF file using Java on Android

If anyone wants to generate PDFs on Android device, here is how to do it:

• http://sourceforge.net/projects/itext/ (library)
• http://www.vogella.de/articles/JavaPDF/article.html (tutorial)
• http://tutorials.jenkov.com/java-itext/image.html (images tutorial)