ResearchPaper.java

interface ResearchPaper 
{
    void view();
  
}
class FullResearchPaper implements ResearchPaper
 {
    private String pdfPath;
     private String authorName;
    public FullResearchPaper(String pdfPath)
     {
        this.pdfPath = pdfPath;
        loadPdf();
    }
   public String getAuthorName() {
    return authorName;
   }
    private void loadPdf() 
    {
        System.out.println("Loading entire PDF from: " + pdfPath);
        
    }

    @Override
    public void view() 
    {
        System.out.println("Viewing PDF: " + pdfPath);
    }
}

class LazyResearchPaper implements ResearchPaper
 {
    private String pdfPath;
    private boolean loaded = false;
    public LazyResearchPaper(String pdfPath)
     {
        this.pdfPath = pdfPath;
    }
    private void loadPdf()
     {
        System.out.println("Loading entire PDF from: " + pdfPath);
        loaded = true;
    }

    @Override
    public void view() 
    {
        if (!loaded) 
        {
            loadPdf();
        }
        System.out.println("Viewing PDF: " + pdfPath);
    }
}

class Main {
    public static void main(String[] args)
     {
        ResearchPaper[] papers = {
            new FullResearchPaper("paper1.pdf"),
            new LazyResearchPaper("paper2.pdf"),
            new LazyResearchPaper("paper3.pdf")
        };

        System.out.println("Browsing papers...");
        for (int i = 0; i < papers.length; i++) 
        {
            System.out.println("Paper " + (i + 1));
        }

        System.out.println("\nOpening paper 2:");
        papers[1].view();
    }
}