driver.java

Java程序设计(美) David D. Riley著 机械工业出版社 书籍配套 代码

import java.io.*;

/** Program to create a new file, called example.txt  (Figure 13.6)
 *  Author: David Riley
 *  Date: January, 2005
 */
public class Driver  {
	public Driver()   {
		try{
			File  file;
        	boolean createOK;
            file = new File( "example.txt" );
        	if ( file.exists() )   {
                if ( file.isDirectory() )   {            									
                    System.out.println( file.getAbsolutePath()
                           	    + " is a directory.  No file created.");
                } else {
                    boolean deleteOK = file.delete();
                    if ( deleteOK )   {
                        System.out.println("Existing file deleted.");
                        createOK = file.createNewFile();
                        if ( createOK )   {
                            System.out.println("File created. "); 
                        } else {
                            System.out.println( "Unable to create file " 
                                          + file.getAbsolutePath() );
                        }
					} else {
                        System.out.println( "Unable to delete file " 
                                       + file.getAbsolutePath() );
					}
                }
 			} else {  // file doesn't exist
                createOK = file.createNewFile();
                if ( createOK )   {
                    System.out.println("File created. ");
                } else {
					System.out.println( "Unable to create file " 
                                    + file.getAbsolutePath() );
     			}
            }
		}
		catch (IOException e)   {
			System.out.println( "I/O error occured");
		}
	}

	/**	pre:	relativePath is a file name for a file relative to the 
	 *			folder that contains this class 
	 *	post:	result is the complete path name associated with relativePath 
	 */
	private String completePath(String relativePath) throws IOException   {
		java.net.URL url = getClass().getResource(relativePath);
		if (url == null)
			throw new IOException("invalid relative file name");
		else
			return url.getPath();
	}
}