EasyReader

Definition

EasyReader is a class that allows data to be inputted into java. It was created by Gary Litvin.

Selected EasyReader Methods

Here are some common EasyReader methods.

Read Word

This method reads a word.

public static void main(String[] args){
    EasyReader er = new EasyReader();
    System.out.print("Who is absent today?");
    String name = er.readWord();
    System.out.print(name + " is absent, and Michael Reidler dropped out.");
}

Read int

This methods reads an int.

public static void main(String[] args){
    EasyReader er = new EasyReader();
    System.out.print("How many people are in the Computer Science class?");
    double people = (double) er.readInt() * .4;
    System.out.print(people + " people will drop out of this class.");
}

Code

public class EasyReader
{
  protected String myFileName;
  protected BufferedReader myInFile;
  protected int myErrorFlags = 0;
  protected static final int OPENERROR = 0x0001;
  protected static final int CLOSEERROR = 0x0002;
  protected static final int READERROR = 0x0004;
  protected static final int EOF = 0x0100;
 
  /**
   *  Constructor.  Prepares console (System.in) for reading
   */
  public EasyReader()
  {
    myFileName = null;
    myErrorFlags = 0;
    myInFile = new BufferedReader(
                            new InputStreamReader(System.in), 128);
  }
 
  /**
   *  Constructor.  opens a file for reading
   *  @param fileName the name or pathname of the file
   */
  public EasyReader(String fileName)
  {
    myFileName = fileName;
    myErrorFlags = 0;
    try
    {
      myInFile = new BufferedReader(new FileReader(fileName), 1024);
    }
    catch (FileNotFoundException e)
    {
      myErrorFlags |= OPENERROR;
      myFileName = null;
    }
  }
 
  /**
   *  Closes the file
   */
  public void close()
  {
    if (myFileName == null)
      return;
    try
    {
      myInFile.close();
    }
    catch (IOException e)
    {
      System.err.println("Error closing " + myFileName + "\n");
      myErrorFlags |= CLOSEERROR;
    }
  }
 
  /**
   *  Checks the status of the file
   *  @return true if en error occurred opening or reading the file,
   *  false otherwise
   */
  public boolean bad()
  {
    return myErrorFlags != 0;
  }
 
  /**
   *  Checks the EOF status of the file
   *  @return true if EOF was encountered in the previous read
   *  operation, false otherwise
   */
  public boolean eof()
  {
    return (myErrorFlags & EOF) != 0;
  }
 
  private boolean ready() throws IOException
  {
    return myFileName == null || myInFile.ready();
  }
 
  /**
   *  Reads the next character from a file (any character including
   *  a space or a newline character).
   *  @return character read or <code>null</code> character
   *  (Unicode 0) if trying to read beyond the EOF
   */
  public char readChar()
  {
    char ch = '\u0000';
 
    try
    {
      if (ready())
      {
         ch = (char)myInFile.read();
      }
    }
    catch (IOException e)
    {
      if (myFileName != null)
        System.err.println("Error reading " + myFileName + "\n");
      myErrorFlags |= READERROR;
    }
 
    if (ch == '\u0000')
      myErrorFlags |= EOF;
 
    return ch;
  }
 
  /**
   *  Reads from the current position in the file up to and including
   *  the next newline character.  The newline character is thrown away
   *  @return the read string (excluding the newline character) or
   *  null if trying to read beyond the EOF
   */
  public String readLine()
  {
    String s = null;
 
    try
    {
      s = myInFile.readLine();
    }
    catch (IOException e)
    {
      if (myFileName != null)
        System.err.println("Error reading " + myFileName + "\n");
      myErrorFlags |= READERROR;
    }
 
    if (s == null)
      myErrorFlags |= EOF;
    return s;
  }
 
  /**
   *  Skips whitespace and reads the next word (a string of consecutive
   *  non-whitespace characters (up to but excluding the next space,
   *  newline, etc.)
   *  @return the read string or null if trying to read beyond the EOF
   */
  public String readWord()
  {
    StringBuffer buffer = new StringBuffer(128);
    char ch = ' ';
    int count = 0;
    String s = null;
 
    try
    {
      while (ready() && Character.isWhitespace(ch))
        ch = (char)myInFile.read();
      while (ready() && !Character.isWhitespace(ch))
      {
        count++;
        buffer.append(ch);
        myInFile.mark(1);
        ch = (char)myInFile.read();
      };
 
      if (count > 0)
      {
        myInFile.reset();
        s = buffer.toString();
      }
      else
      {
        myErrorFlags |= EOF;
      }
    }
 
    catch (IOException e)
    {
      if (myFileName != null)
        System.err.println("Error reading " + myFileName + "\n");
      myErrorFlags |= READERROR;
    }
 
    return s;
  }
 
  /**
   *  Reads the next integer (without validating its format)
   *  @return the integer read or 0 if trying to read beyond the EOF
   */
  public int readInt()
  {
    String s = readWord();
    if (s != null)
      return Integer.parseInt(s);
    else
      return 0;
  }
 
  /**
   *  Reads the next double (without validating its format)
   *  @return the number read or 0 if trying to read beyond the EOF
   */
  public double readDouble()
  {
    String s = readWord();
    if (s != null)
      return Double.parseDouble(s);
      // in Java 1, use: return Double.valueOf(s).doubleValue();
    else
      return 0.0;
  }
}
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