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package sun.tools.jstat;

import java.util.*;


A typesafe enumeration for describing mathematical operators.
Author:Brian Doherty
Since:1.5
/** * A typesafe enumeration for describing mathematical operators. * * @author Brian Doherty * @since 1.5 */
public abstract class Operator { private static int nextOrdinal = 0; private static HashMap<String, Operator> map = new HashMap<String, Operator>(); private final String name; private final int ordinal = nextOrdinal++; private Operator(String name) { this.name = name; map.put(name, this); } protected abstract double eval(double x, double y); /* Operator '+' */ public static final Operator PLUS = new Operator("+") { protected double eval(double x, double y) { return x + y; } }; /* Operator '-' */ public static final Operator MINUS = new Operator("-") { protected double eval(double x, double y) { return x - y; } }; /* Operator '/' */ public static final Operator DIVIDE = new Operator("/") { protected double eval(double x, double y) { if (y == 0) { return Double.NaN; } return x / y; } }; /* Operator '*' */ public static final Operator MULTIPLY = new Operator("*") { protected double eval(double x, double y) { return x * y; } };
Returns the string representation of this Operator object.
Returns: the string representation of this Operator object
/** * Returns the string representation of this Operator object. * * @return the string representation of this Operator object */
public String toString() { return name; }
Maps a string to its corresponding Operator object.
Params:
  • s – an string to match against Operator objects.
Returns: The Operator object matching the given string.
/** * Maps a string to its corresponding Operator object. * * @param s an string to match against Operator objects. * @return The Operator object matching the given string. */
public static Operator toOperator(String s) { return map.get(s); }
Returns an enumeration of the keys for this enumerated type
Params:
  • s – an string to match against Operator objects.
Returns: The Operator object matching the given string.
/** * Returns an enumeration of the keys for this enumerated type * * @param s an string to match against Operator objects. * @return The Operator object matching the given string. */
protected static Set<?> keySet() { return map.keySet(); } }