Java Dialog box to allow use to pick file

Question

This is the code I have at present:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;
import java.util.*;
import java.io.File;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class XMLReader extends JFrame
{
   JFileChooser _fileChooser = new JFileChooser();
   JPanel content = new JPanel();

       //... Create menu elements (menubar, menu, menu item)
       JMenuBar menubar  = new JMenuBar();
       JMenu    fileMenu = new JMenu("File");
       JMenuItem openItem = new JMenuItem("Open...");
       int retval = _fileChooser.showOpenDialog(XMLReader.this);
            //... The user selected a file, get it, use it.
     public static void main(String argv[]) 
     {
         ArrayList timeStamp = new ArrayList();
         ArrayList Y = new ArrayList();
         File file = XMLReader.this;
         DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
         DocumentBuilder db = dbf.newDocumentBuilder();
         Document doc = db.parse(file);
         doc.getDocumentElement().normalize();
         System.out.println("Root element " + doc.getDocumentElement().getNodeName());
         NodeList nodeLst = doc.getElementsByTagName("reading");
         System.out.println("Share Data");

         for (int s = 0; s < nodeLst.getLength(); s++) {

         Node fstNode = nodeLst.item(s);

         if (fstNode.getNodeType() == Node.ELEMENT_NODE) {

          Element fstElmnt = (Element) fstNode;
          NodeList fstNmElmntLst = fstElmnt.getElementsByTagName("timeStamp");
         .
         .
         .
   }

I am trying to get a dialog box to allow the user to pick the XML they want parsed. I know the parsing works as I had hard coded in the file before.

I would also like to return the ArrayLists so that I can use them as the inputs to another class is this possible (at the moment I am only printing them to screen)?

System.out.println(timeStamp);
System.out.println(Y);

Can I use a return statement and if so how to I set up the class that I want to use them in?

Answer 1

The dialog box serve to retrive the path

I see that You are using the awt and dom so:

public Document loadXmlFile(Frame frame, DocumentBuilder docBuilder, String startPath) {

    FileDialog fd = new FileDialog(frame, "Loadxml-title", FileDialog.LOAD);
     //Add type filter 
     fd.setDirectory(startPath));     
     fd.show();

    String file = fd.getFile();

    if(file == null) {
      return null;
    } 

    return  docBuilder.parse(file);

}

Answer 2

Q2: "Error message when compiling, can't have DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); with throw or catch exception."

This error is raised bu compiler because You don't have the block try & catch in method main.

The definition of DocumentBuilderFactory.newInstace(); says that this method throw the FactoryConfigurationError. In Java when method throw some error and it is not a RuntimeException you need to throw it in method definition or add the try catch block to handle it.

 DocumentBuilderFactory dbf = null;

 try {
  dbf = DocumentBuilderFactory.newInstance();
 } Exception(FactoryConfigurationError e){
    e.printStackTrace();
 }