How to preserve command prompt's formatting inside a jTextArea (or some other type of console)?

Question

I cannot figure out how to preserve command prompt\'s formatting when I output the stream inside a Java program. Anyone have any suggestions?

Answer 1

There are a number of possible solutions available to you depending on how your data is derived...

The most basic would be to ensure you are using a fixed width font...

import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class OutputTest {

    public static void main(String[] args) {
        new OutputTest();
    }

    public OutputTest() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane() {
            String[] lines = {
                "Idx     Met        MTU        State                Name           ",
                "---  ---------  ----------  ------------  --------------------------",
                "  1         50  4294967295  connected     Loopback Psudo-Interface 1",
                " 11         10        1500  connected     Local Area Connection     ",
                " 11          5        1500  disconnected  Local Area Connection 3   ",
            };

            setLayout(new BorderLayout());
            JTextArea ta = new JTextArea(10, 40);
            ta.setFont(new Font("Monospaced", Font.PLAIN, 13));
            for (String text : lines) {
                ta.append(text + "\n");
            }
            add(new JScrollPane(ta));
        }

    }

}

This is great if your piping content from another source (like an external command).

If you have control of the content, you could use String.format, but again, unless you're using a fixed width font, it won't make any difference, you will still have formatting issues.

Another solution would be to use a html table in a JEditorPane, then the font doesn't matter

Another solution might be to use a JTable which is designed to present data in a tabular form. See How to Use Tables for more details

Updated

It's a bug with the auto generated code in Netbeans 8.0 I'm pretty sure. It just made it tough to track down the issue.

I doubt very highly that it's a bug, as this is been used by hundreds if not thousands of people every day...but without a runnable example which demonstrates your problem it's impossible to know for sure...

ta.setFont(new Font("Monospaced", Font.PLAIN, 13)); BUT if you switch to bold or italics or bold italics then the line is generated and works correctly.

I beg to differ...

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.GridLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class TestTable {

    public static void main(String[] args) {
        new TestTable();
    }

    public TestTable() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane() {
            setLayout(new GridLayout(4, -1));
            String[] lines = {
                "Idx     Met        MTU        State                Name           ",
                "---  ---------  ----------  ------------  --------------------------",
                "  1         50  4294967295  connected     Loopback Psudo-Interface 1",
                " 11         10        1500  connected     Local Area Connection     ",
                " 11          5        1500  disconnected  Local Area Connection 3   ",};

            Font baseFont = new Font("Monospaced", Font.PLAIN, 13);
            addTextArea(baseFont, lines);
            addTextArea(baseFont.deriveFont(Font.ITALIC), lines);
            addTextArea(baseFont.deriveFont(Font.BOLD), lines);
            addTextArea(baseFont.deriveFont(Font.BOLD | Font.ITALIC), lines);
        }

        protected void addTextArea(Font font, String... lines) {

            JTextArea ta = new JTextArea(20, 40);
            ta.setFont(font);
            for (String text : lines) {
                ta.append(text + "\n");
            }
            ta.setCaretPosition(0);
            add(new JScrollPane(ta));
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

    }
}