I am new to java and trying following example. With the code below, I can print all nodes of a XML file. Now I would like to use Swing and put it out in a simple Swing window.

I understand how to create a window, but how can I connect the console output to a JTextArea? I searched for it on stackoverflow but did not get the right idea.

I thank you much in advance.

Best regards,

public static void main(String[] args) throws IOException 
{
    try  
    { 
        File file = new File("dum.xml");
        DocumentBuilder documentBuilder = DocumentBuilderFactory.newInstance().newDocumentBuilder(); 
        Document document = documentBuilder.parse(file); 
        System.out.println("Root element: "  document.getDocumentElement().getNodeName()); 
        if (document.hasChildNodes())  
        { 
            printNodeList(document.getChildNodes());
        } 
    }  
    catch (Exception e) 
    { 
        System.out.println(e.getMessage()); 
    } 
} 

private static void printNodeList(NodeList nodeList) 
{ 
    for (int count = 0; count < nodeList.getLength(); count  )
    { 
        Node elemNode = nodeList.item(count); 
        if (elemNode.getNodeType() == Node.ELEMENT_NODE)  
        { 
            // get node name and value 
            System.out.println("\nZeilenname ="   elemNode.getNodeName()  " [Anfang]");
            System.out.println("Zeileninhalt ="   elemNode.getTextContent()); 
            if (elemNode.hasAttributes())  
            {
                NamedNodeMap nodeMap = elemNode.getAttributes();
                for (int i = 0; i < nodeMap.getLength(); i  )
                {
                    Node node = nodeMap.item(i);
                    System.out.println("Attributname : "   node.getNodeName()); 
                    System.out.println("Attributwert : "   node.getNodeValue()); 
                }
            }
            if (elemNode.hasChildNodes())  
            {
                //recursive call if the node has child nodes
                printNodeList(elemNode.getChildNodes());
            }
            System.out.println("Zeilenname ="   elemNode.getNodeName()  " [Ende]"); 
        }
    } 
}

CodePudding user response：

This is how to create the main frame for a Java Swing application following best practices (i.e. use SwingUtilities#invokeLater(...) to run your Swing application.

public class SwingDemo {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
    
    private static void createAndShowGUI() {
        JFrame f = new JFrame("Swing Demo");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setSize(250,250);
        f.setVisible(true);
    }
}

Now you need to add the component to display text. JLabel, JTextField, and JTextAreaare the main candidates. Since you mentioned text area, let use that component. For that, all you need to do is add these two lines at the end:

    String text = "Hello World!";
    JTextArea textarea = new JTextArea();
    textarea.setText(text);
    f.add(textarea);
    textarea.append("\nI added this later"); // UPDATE

You can then modify this sample code so it looks better. For example, you can instead put the text area in a JPanel and you could then use layouts to control the placement and size of the panel in order to prevent the text area to expand to the size of the entire JFrame. But this minimalist code does exactly what you wanted, which is to set text in a Java Swing GUI.

UPDATE: You could use the append() method to add lines to your GUI. For example:

NamedNodeMap nodeMap = elemNode.getAttributes(); 
for (int i = 0; i < nodeMap.getLength(); i  )  
{ 
    Node node = nodeMap.item(i); 
    textarea.append("\nAttributname : "   node.getNodeName());
}

CodePudding user response：

Create a JTextArea. Replace all calls to System.out.println with JTextArea.append. Below code demonstrates.

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.io.File;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class XmlSwing {
    private JTextArea textArea;

    private void createAndDisplayGui() {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(createTextArea(), BorderLayout.CENTER);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    private JScrollPane createTextArea() {
        textArea = new JTextArea(20, 40);
        createTextAreaText();
        JScrollPane scrollPane = new JScrollPane(textArea);
        return scrollPane;
    }

    private void createTextAreaText() {
        try {
            File file = new File("dum.xml");
            DocumentBuilder documentBuilder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
            Document document = documentBuilder.parse(file);
            textArea.append("Root element: "   document.getDocumentElement().getNodeName()   "\n");
            if (document.hasChildNodes()) {
                printNodeList(document.getChildNodes());
            }
        }
        catch (Exception e) {
            System.out.println(e.getMessage());
        }
    }

    private void printNodeList(NodeList nodeList) {
        for (int count = 0; count < nodeList.getLength(); count  ) {
            Node elemNode = nodeList.item(count);
            if (elemNode.getNodeType() == Node.ELEMENT_NODE) {
                // get node name and value
                textArea.append("\nZeilenname ="   elemNode.getNodeName()   " [Anfang]\n");
                textArea.append("Zeileninhalt ="   elemNode.getTextContent()   "\n");
                if (elemNode.hasAttributes()) {
                    NamedNodeMap nodeMap = elemNode.getAttributes();
                    for (int i = 0; i < nodeMap.getLength(); i  ) {
                        Node node = nodeMap.item(i);
                        textArea.append("Attributname : "   node.getNodeName()   "\n");
                        textArea.append("Attributwert : "   node.getNodeValue()   "\n");
                    }
                }
                if (elemNode.hasChildNodes()) {
                    // recursive call if the node has child nodes
                    printNodeList(elemNode.getChildNodes());
                }
                textArea.append("Zeilenname ="   elemNode.getNodeName()   " [Ende]\n");
            }
        }
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(() -> new XmlSwing().createAndDisplayGui());
    }
}

Refer to Creating a GUI With Swing