TextFileInput.java

http://dnixon.nyclocal.net/qc/cs212/proj-2-hints/TextFileInput.java.html

// TextFileInput.java // Copyright (c) 2000, 2005 Dorothy L. Nixon.  All rights reserved.  import java.io.BufferedReader; import java.io.FileInputStream; import java.io.InputStreamReader; import java.io.IOException;  /**  * Simplified buffered character input  * stream from an input text file.  * Manages an input text file,  * handling all IOExceptions by generating  * RuntimeExcpetions (run-time error  * messages).  *  * If the text file cannot be created,  * a RuntimeException is thrown,  * which by default results an an  * error message being printed to  * the standard error stream.  *  * @author D. Nixon  */ public class TextFileInput  {     /**  Name of text file  */    private String filename;     /**  Buffered character stream from file  */    private BufferedReader br;       /**  Count of lines read so far.  */    private int lineCount = 0;     /**     * Creates a buffered character input     * strea, for the specified text file.     *     * @param filename the input text file.     * @exception RuntimeException if an     *          IOException is thrown when     *          attempting to open the file.     */    public TextFileInput(String filename)    {       this.filename = filename;       try  {          br = new BufferedReader(                   new InputStreamReader(                       new FileInputStream(filename)));       } catch ( IOException ioe )  {          throw new RuntimeException(ioe);       }  // catch    }  // constructor     /**     * Closes this character input stream.     * No more characters can be read from     * this TextFileInput once it is closed.     * @exception NullPointerException if     *        the file is already closed.     * @exception RuntimeException if an     *       IOException is thrown when     *       closing the file.     */    public void close()    {       try  {          br.close();          br = null;       } catch ( NullPointerException npe )  {          throw new NullPointerException(                         filename + "already closed.");       } catch ( IOException ioe )  {          throw new RuntimeException(ioe);       }  // catch    }  // method close     /**     * Reads a line of text from the file and     * positions cursor at 0 for the next line.     * Reads from the current cursor position     * to end of line.     * Implementation does not invoke read.     *     * @return the line of text, with     *         end-of-line marker deleted.     * @exception RuntimeException if an     *          IOException is thrown when     *          attempting to read from the file.     */    public String readLine()    {       return readLineOriginal();    }  // method readLine()     /**     * Returns a count of lines     * read from the file so far.     */    public int getLineCount()  { return lineCount; }     /**     * Tests whether the specified character is equal,     * ignoring case, to one of the specified options.     *     * @param toBeChecked the character to be tested.     * @param options a set of characters     * @return true if toBeChecked is     *         equal, ignoring case, to one of the     *         options, false otherwise.     */    public static boolean isOneOf(char toBeChecked,                                  char[] options)    {       boolean oneOf = false;       for ( int i = 0; i < oneof =" true;">toBeChecked     *         contains the same sequence of     *         characters, ignoring case, as one of the     *         options, false otherwise.     */    public static boolean isOneOf(String toBeChecked,                                  String[] options)    {       boolean oneOf = false;       for ( int i = 0; i < oneof =" true;" options ="="" length ="="" answer =" readLine();" answer ="="" optionstring =" options[0];" i =" 1;">true if the line matches     *        "Y", "yes", "1" "T", or "true".     *        false if the line matches     *        "N", "no", "0", "F", or "false".     * @exception RuntimeException if the line of text     *        does not match one of "Y", "N", "yes",     *        "no", "1", "0", "T", "F", "true", or "false",     *        or if an IOException is thrown when reading     *        from the file.     * @exception NullPointerException if the end of the     *        file has been reached.     */    public boolean readBooleanSelection()    {       String[] options = {"Y", "N", "yes", "no", "1", "0",                           "T", "F", "true", "false"};       String answer = readSelection(options);       return isOneOf(answer,                      new String[] {"Y", "yes", "1", "T", "true"} );    }  // method askUserYesNo     /**     * Reads a line of text from the file and     * increments line count.  (This method     * is called by public readLine and is     * final to facilitate avoidance of side     * effects when public readLine is overridden.)     *     * @return the line of text, with     *         end-of-line marker deleted.     * @exception RuntimeException if an     *          IOException is thrown when     *          attempting to read from the file.     */    protected final String readLineOriginal()    {        try  {           if ( br == null )              throw new RuntimeException(                                 "Cannot read from closed file "                                 + filename + ".");           String line = br.readLine();           if ( line != null )              lineCount++;           return line;        } catch (IOException ioe)  {           throw new RuntimeException(ioe);        }  // catch    }  // method readLineOriginal }  // class TextFileInput