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amitguptagwl/VisitorPatternExample.java

Created October 15, 2016 19:31
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  1. amitguptagwl created this gist Oct 15, 2016.
    99 changes: 99 additions & 0 deletions VisitorPatternExample.java
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,99 @@
    import java.util.ArrayList;
    import java.util.List;
    import java.util.stream.Collectors;
    import java.util.stream.Stream;

    public class VisitorPatternExample {
    public static void main(String[] args) {
    List<String> list = new ArrayList<String>();
    //list.add("java");
    list.add("pdf");
    list.add("html");

    list.forEach(file -> {
    FileOperator head = new Head();
    FileUtil.fileIdentifier(file).doFileOperation(head);
    });
    }
    }

    //Visitable
    interface ReadableFile {
    public String readNextLine();
    public void doFileOperation(FileOperator operator);
    }

    class PdfFile implements ReadableFile {

    PdfFile(String fileName) {
    // Create instance of File
    }

    public String readNextLine() {
    return "Reading line from a PDF";
    }

    @Override
    public void doFileOperation(FileOperator operator) {
    operator.processPdfFile(this);
    }

    public boolean isSecure() {
    return false;
    }
    }

    class HtmlFile implements ReadableFile {

    HtmlFile(String fileName) {
    // Create instance of File
    }

    public String readNextLine() {
    return "Reading line from a HTML";
    }

    @Override
    public void doFileOperation(FileOperator operator) {
    operator.processHtmlFile(this);
    }
    }

    interface FileOperator{
    public void processPdfFile(PdfFile file);
    public void processHtmlFile(HtmlFile file);
    }

    class Head implements FileOperator{

    public void operation(PdfFile file) {
    file.readNextLine();
    }

    @Override
    public void processPdfFile(PdfFile file) {
    if(file.isSecure()){
    System.out.println("Can't read secure file");
    }else{
    System.out.println(file.readNextLine());
    }
    }

    @Override
    public void processHtmlFile(HtmlFile file) {
    System.out.println(file.readNextLine());
    }


    }

    class FileUtil {
    public static ReadableFile fileIdentifier(String fileName) {
    if (fileName.toString().contains("pdf"))
    return new PdfFile(fileName);
    else if (fileName.toString().contains("html"))
    return new HtmlFile(fileName);
    return null;
    }

    }