how can I do to simulate a class of type enum in java <5.0 ..??
public final class Week {
private static final Day[] _week = {Day.MONDAY, Day.TUESDAY, Day.WEDNESDAY, Day.THURSDAY, Day.FRIDAY, Day.SATURDAY, Day.SUNDAY};
public static Day getDayOfWeek(final int index) {
if (index >= 1 && index <= 7) {
return _week[index - 1];
}
throw new IndexOutOfBoundsException("Invalid index [1..7]");
}
public static final class Day {
public static final Day MONDAY = new Day(1, "Monday");
public static final Day TUESDAY = new Day(2, "Tuesday");
public static final Day WEDNESDAY = new Day(3, "Wednesday");
public static final Day THURSDAY = new Day(4, "Thursday");
public static final Day FRIDAY = new Day(5, "Friday");
public static final Day SATU开发者_如何学编程RDAY = new Day(6, "Saturday");
public static final Day SUNDAY = new Day(7, "Sunday");
private int _value;
private String _name;
private Day(final int value, final String name) {
_value = value;
_name = name;
}
/* (non-Javadoc)
* @see java.lang.Object#toString()
*/
public String toString() {
return "[Day] " + _name;
}
/* (non-Javadoc)
* @see java.lang.String#equals(java.lang.Object)
*/
public boolean equals(Object anObject) {
Day d = (Day)anObject;
return _value == d._value;
}
}
public static void main(String[] agrs) {
System.out.println(Week.getDayOfWeek(2));
}
}
Use the typesafe enum described in effective java. Here is an example given from Joshua Blochs article on this:
// The typesafe enum pattern
public class Suit {
private final String name;
private Suit(String name) { this.name = name; }
public String toString() { return name; }
public static final Suit CLUBS =
new Suit("clubs");
public static final Suit DIAMONDS =
new Suit("diamonds");
public static final Suit HEARTS =
new Suit("hearts");
public static final Suit SPADES =
new Suit("spades");
}
If you want your typesafe enum to be Serializable, remember to control reconstruction via the readResolve
method.
Joshua Bloch wrote, long ago, an article explaining it.
Joshua Bloch shows you how in the first edition of his "Effective Java". I have to go to work, so I can't type in details now. More to follow.
The solution Krock and Riduidel are suggesting is pretty neat, but AFAIK a switch-case
statement won't be possible as it's applicable only for convertible int
values and enum
constants.
switch-case
combination is a nice feature, more readable than a bunch of if
s (BTW: switch-case
will be compiled as a bunch of if
s anyway, correct?). So, to complete the discussed pattern, could someone tell whether there is a quick way to enable this patteren with functionality allowing switch-case
? Adding an int
property and getter for it seems the simplest way, but is it the optimal?
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