ExecDemoNS.java Source code

Introduction

Here is the source code for ExecDemoNS.java

Source

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;
import java.net.*;
import java.util.*;

/**
 * ExecDemoNS shows how to execute a program from within Java.
 */
public class ExecDemoNS extends JFrame {
    /** The name of the help file. */
    protected final static String HELPFILE = "./help/index.html";

    /** A stack of process objects; each entry tracks one external running process */
    Stack<Process> pStack = new Stack<Process>();

    /** main - instantiate and run */
    public static void main(String av[]) throws Exception {
        String program = av.length == 0 ? "netscape" : av[0];
        new ExecDemoNS(program).setVisible(true);
    }

    /** The path to the binary executable that we will run */
    protected static String program;

    /** Constructor - set up strings and things. */
    public ExecDemoNS(String prog) {
        super("ExecDemo: " + prog);
        String osname = System.getProperty("os.name");
        if (osname == null)
            throw new IllegalArgumentException("no os.name");
        if (prog.equals("netscape"))
            program = // Windows or UNIX only for now, sorry Mac fans
                    (osname.toLowerCase().indexOf("windows") != -1)
                            ? "c:/program files/netscape/communicator/program/netscape.exe"
                            : "/usr/local/netscape/netscape";
        else
            program = prog;

        Container cp = getContentPane();
        cp.setLayout(new FlowLayout());
        JButton b;
        cp.add(b = new JButton("Exec"));
        b.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
                runProg();
            }
        });
        cp.add(b = new JButton("Wait"));
        b.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
                doWait();
            }
        });
        cp.add(b = new JButton("Exit"));
        b.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
                System.exit(0);
            }
        });
        pack();
    }

    /** Start the help, in its own Thread. */
    public void runProg() {

        new Thread() {
            public void run() {

                try {
                    // Get the URL for the Help File
                    URL helpURL = this.getClass().getClassLoader().getResource(HELPFILE);

                    // Start Netscape from the Java Application.

                    pStack.push(Runtime.getRuntime().exec(program + " " + helpURL));

                } catch (Exception ex) {
                    JOptionPane.showMessageDialog(ExecDemoNS.this, "Error" + ex, "Error",
                            JOptionPane.ERROR_MESSAGE);
                }
            }
        }.start();

    }

    public void doWait() {
        if (pStack.size() == 0)
            return;
        try {
            pStack.peek().waitFor();
            // wait for process to complete (does not work as expected for Windows programs)
        } catch (Exception ex) {
            JOptionPane.showMessageDialog(this, "Error" + ex, "Error", JOptionPane.ERROR_MESSAGE);
        }
        pStack.pop();
    }
}