Delete.java Source code

Introduction

Here is the source code for Delete.java

Source

/*
 * Copyright (c) 2004 David Flanagan.  All rights reserved.
 * This code is from the book Java Examples in a Nutshell, 3nd Edition.
 * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
 * You may study, use, and modify it for any non-commercial purpose,
 * including teaching and use in open-source projects.
 * You may distribute it non-commercially as long as you retain this notice.
 * For a commercial use license, or to purchase the book, 
 * please visit http://www.davidflanagan.com/javaexamples3.
 */

import java.io.File;

/**
 * This class is a static method delete() and a standalone program that deletes
 * a specified file or directory.
 */
public class Delete {
    /**
     * This is the main() method of the standalone program. After checking it
     * arguments, it invokes the Delete.delete() method to do the deletion
     */
    public static void main(String[] args) {
        if (args.length != 1) { // Check command-line arguments
            System.err.println("Usage: java Delete <file or directory>");
            System.exit(0);
        }
        // Call delete() and display any error messages it throws.
        try {
            delete(args[0]);
        } catch (IllegalArgumentException e) {
            System.err.println(e.getMessage());
        }
    }

    /**
     * The static method that does the deletion. Invoked by main(), and designed
     * for use by other programs as well. It first makes sure that the specified
     * file or directory is deleteable before attempting to delete it. If there is
     * a problem, it throws an IllegalArgumentException.
     */
    public static void delete(String filename) {
        // Create a File object to represent the filename
        File f = new File(filename);

        // Make sure the file or directory exists and isn't write protected
        if (!f.exists())
            fail("Delete: no such file or directory: " + filename);
        if (!f.canWrite())
            fail("Delete: write protected: " + filename);

        // If it is a directory, make sure it is empty
        if (f.isDirectory()) {
            String[] files = f.list();
            if (files.length > 0)
                fail("Delete: directory not empty: " + filename);
        }

        // If we passed all the tests, then attempt to delete it
        boolean success = f.delete();

        // And throw an exception if it didn't work for some (unknown) reason.
        // For example, because of a bug with Java 1.1.1 on Linux,
        // directory deletion always fails
        if (!success)
            fail("Delete: deletion failed");
    }

    /** A convenience method to throw an exception */
    protected static void fail(String msg) throws IllegalArgumentException {
        throw new IllegalArgumentException(msg);
    }
}