text.java

Java经典例程 从外国一大学计算机教授出版物下载的代码 经典

package javagently;

import java.io.*;
import java.util.*;
import java.text.*;

public class Text {

  public Text () {};

  /* The All New Famous Text class     by J M Bishop  Aug 1996
   *            revised for Java 1.1 by Alwyn Moolman Aug 1997
   *            revised for efficiency by J M Bishop Dec 1997
   *
   * Provides simple input from the keyboard and files.
   * Now also has simple output formatting methods
   * and file opening facilities.
   *
   * public static void   prompt (String s)
   * public static int    readInt (BufferedReader in)
   * public static double readDouble (BufferedReader in)
   * public static String readString (BufferedReader in)
   * public static char   readChar (BufferedReader in)
   * public static String writeInt (int number, int align)
   * public static String writeDouble
                   (double number, int align, int frac)
   * public static BufferedReader open (InputStream in)
   * public static BufferedReader open (String filename)
   * public static PrintWriter create (String filename)
   *
   * January 2001
   * Now local to the javagently package as it has been
   * superceded for program development by the Stream class.
   * It is still needed by Graph and Display.
   */

  private static StringTokenizer T;
  private static String S;

  public static BufferedReader open (InputStream in)  {
    return new BufferedReader(new InputStreamReader(in));
  }

  public static BufferedReader open (String filename)
	throws FileNotFoundException {
    return new BufferedReader (new FileReader (filename));
  }

  public static PrintWriter create
	 (String filename) throws IOException {
    return new PrintWriter (new FileWriter (filename));
  }

  public static void prompt (String s) {
    System.out.print(s + " ");
    System.out.flush();
  }

  public static int readInt (BufferedReader in) throws IOException {
      if (T==null) refresh(in);
      while (true) {
        try {
          return Integer.parseInt(T.nextToken());
        }
        catch (NoSuchElementException e1) {
          refresh (in);
        }
        catch (NumberFormatException e2) {
          System.out.println("Error in number, try again.");
        }
      }
   }

 public static char readChar (BufferedReader in) throws IOException {
      if (T==null) refresh(in);
      while (true) {
        try {
          return T.nextToken().trim().charAt(0);
        }
        catch (NoSuchElementException e1) {
          refresh (in);
        }
      }
   }

 public static double readDouble (BufferedReader in) throws IOException {
      if (T==null) refresh(in);
      while (true) {
        try {
          String item = T.nextToken();
          return Double.valueOf(item.trim()).doubleValue();
        }
        catch (NoSuchElementException e1) {
          refresh (in);
        }
        catch (NumberFormatException e2) {
          System.out.println("Error in number, try again.");
        }
      }
   }

  public static String readString (BufferedReader in) throws IOException {
    if (T==null) refresh (in);
    while (true) {
      try {
        return T.nextToken();
      }
      catch (NoSuchElementException e1) {
        refresh (in);
      }
    }
  }

  private static void refresh (BufferedReader in) throws IOException {
    S = in.readLine ();
    if (S==null) throw new EOFException();
    T = new StringTokenizer (S);
  }

  //  Write methods
  //  -------------

  private static DecimalFormat N = new DecimalFormat();
  private static final String spaces = "                    ";

  public static String writeDouble (double number, int align, int frac) {
    N.setGroupingUsed(false);
    N.setMaximumFractionDigits(frac);
    N.setMinimumFractionDigits(frac);
    String num = N.format(number);
    if (num.length() < align)
      num = spaces.substring(0,align-num.length()) + num;
    return num;
  }

  public static String writeInt (int number, int align) {
    N.setGroupingUsed(false);
    N.setMaximumFractionDigits(0);
    String num = N.format(number);
    if (num.length() < align)
      num = spaces.substring(0,align-num.length()) + num;
    return num;

  }
}