Set new text in JEditorPane

Question

I am facing a problem when setting new text in JEditorPane in a subclass Index that extends JFrame.

package gui;
...
public class Index extends JFrame {
    JEditorPane editorPaneMR = new JEditorPane();

public static void main(String[] args) {
    ...
}

public Index() {
        JButton SearchButton = new JButton("OK");
        SearchButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                parser GooBlog = new parser(url);
                try {
                    GooBlog.hello(); // Go to subclass parser
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }
    }
}

And this the code of subclass called parser

package gui;
public class parser extends Index{
    String url;

    public parser (String urlInput){
        this.url = urlInput;
    }

    public void hello () throws IOException{
        editorPaneMR.setText("Hello World");
    }
}

The problem is when I pressed OK button it doesn't show me the text "Hello world" in JEditorPane! and it doesn't show me any error, just nothing happened.

Answer 1

The code line

parser GooBlog = new parser(url);

instantiates not only a parser but also a new Index/JFrame. The JEditorPane of this newly created JFrame is used inside method hello and since the frame is not visible, nothing will happen.

A solution might be to provide a reference to your JFrame or JEditorPane into method hello, e.g.

public class Parser {  // does no longer extend Index
    String url;

    public Parser(String urlInput) {
        this.url = urlInput;
    }

    public void hello(JEditorPane editorPane) {  // has argument now
        editorPane.setText("Hello World");
    }
}

which will then be called via

Parser gooBlog = new Parser(url);
gooBlog.hello(Index.this.editorPaneMR);

Note: Please stick to common Java coding standards and use upper case names for classes, i.e. Parser instead of parser, and lower case variable/field/method names, e.g. gooBlog.