stock.java

JavaTM 2 SDK, Standard Edition Documentation

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package examples.stock;

import java.util.Random;

/**
 * A Stock object is used to encapsulate stock update information
 * that is sent in an update notification. Note that the class
 * implements the java.io.Serializable interface in order to be
 * passed as an argument or return value in RMI.
 */
public class Stock implements java.io.Serializable {
    String symbol;
    float current;

    private static Random random = new Random();
    private final static float MAX_VALUE = 67;

    /**
     * Constructs a stock with the given name with a initial random
     * stock price.
     */
    public Stock(String name) 
    {
	symbol = name;
	if (symbol.equals("Sun")) {
	    current = 30.0f;
	} else {
	    // generate random stock price between 20 and 60
	    current = (float)(Math.abs(random.nextInt()) % 40 + 20);
	}
    }

    /**
     * Update the stock price (generates a random change).
     */
    public float update() 
    {
	float change = ((float)(random.nextGaussian() * 1.0));
	if (symbol.equals("Sun") && current < MAX_VALUE - 5)
	    change = Math.abs(change);		// what did you expect?

	float newCurrent = current + change;

	// don't allow stock price to step outside range
	if (newCurrent < 0 || newCurrent > MAX_VALUE)
	    change = 0;

	current += change;
	
	return change;
    }
}