// File: file_io4.java
//
// Author: Rahul Simha
// Created: August 18, 1998.
//
// A useful function to extract information from
// property files.

import java.util.*;

public class file_io4 {

  // Parameters:
  //   in_string: the property string (e.g. "radius=0.9")
  //   property:  the property name (e.g., "radius")
  // The value is assumed to be a real number.

  public static double read_property (String in_string, String property)
  {
    // Obtain a copy of the StringTokenizer object.
    StringTokenizer st = new StringTokenizer (in_string);

    // Get the first token, specifying the delimiter.
    String first_part = st.nextToken ("=");

    // Trim whitespace on either side - a String function.
    first_part = first_part.trim ();

    System.out.println ("First part: " + first_part);

    if (!first_part.equals (property)){
      System.out.println ("Improper string: " + in_string);
      System.exit (0);
    }

    // Get the next token, now allowing for end-of-line.
    String second_part = st.nextToken (" =\t\n\r");

    // Trim whitespace.
    second_part = second_part.trim();

    System.out.println ("Second part: " + second_part);

    // Read the number in the second part using the library's
    // Double object.
    try {
      double d = Double.parseDouble (second_part);
      return d;
    }
    catch (NumberFormatException e) {
      System.out.println ("Second part not a number: " + second_part);
      System.exit (0);
    }
    return 0;
  }

  public static void main (String[] argv)
  {
    // Test
    double d = read_property ("x=5", "x");
    System.out.println (d);

    d = read_property ("center.x=5", "center.x");
    System.out.println (d);

    d = read_property ("center.x=5   ", "center.x");
    System.out.println (d);

    d = read_property (" center.x = 5   ", "center.x");
    System.out.println (d);
  
  }
}