Learning enum

[Pojahn_M]

Enums are useful when it comes to GUI(buttons). I dont know GUI yet, but I dont see a problem with learning enum before GUI.

A simple enum without a values/constructors like other programming languages enum types works fine. But this wont compile:

package pjjava.nbie;

public enum Family
{
	FATHER {56},
	MOTHER {52},
	SON {24},
	DAUGHTER {21},
	BABY {1};

	private final int age;

	Familj (int age)
	{
		this.age = age;
	}
}

And the error message:

C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:5: error: illegal start of type
	FATHER {56},
	        ^
C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:5: error: ';' expected
	FATHER {56},
	          ^
C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:5: error: illegal start of type
	FATHER {56},
	           ^
C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:6: error: ';' expected
	MOTHER {52},
	      ^
C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:6: error: not a statement
	MOTHER {52},
	        ^
C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:6: error: ';' expected
	MOTHER {52},
	          ^
C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:6: error: illegal start of type
	MOTHER {52},
	           ^
C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:6: error: ';' expected
	MOTHER {52},
	            ^
C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:7: error: not a statement
	SON {24},
	     ^
C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:7: error: ';' expected
	SON {24},
	       ^
C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:7: error: illegal start of type
	SON {24},
	        ^
C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:7: error: ';' expected
	SON {24},
	         ^
C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:8: error: not a statement
	DAUGHTER {21},
	          ^
C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:8: error: ';' expected
	DAUGHTER {21},
	            ^
C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:8: error: illegal start of type
	DAUGHTER {21},
	             ^
C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:8: error: ';' expected
	DAUGHTER {21},
	              ^
C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:9: error: not a statement
	BABY {1};
	      ^
C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:9: error: ';' expected
	BABY {1};
	       ^
C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:13: error: invalid method declaration; return type required
	Familj (int age)
	^
C:\Program\Java\jdk1.7.0\jre\classes\pjjava\nbie\Family.java:17: error: reached end of file while parsing
}
 ^
20 errors

Tool completed with exit code 1

[Tolls]

Enums are useful when it comes to GUI(buttons). I dont know GUI yet, but I dont see a problem with learning enum before GUI.

Enums are useful in coding, not just GUI stuff. I have a stack of enums here, and my work is all back end server stuff.

Anywa, your problem is you should use (), not {}. They're essentially calls to the constructor:

    FATHER (56),
.. etc etc

ETA: Oh, and your constructor has a typo...the class is called Family, but the constructor has Familj.

[sunde887]

Tolls is very right, Enums are useful for a lot of stuff. Off the top of my head, I used enums in a card game, and an RPG.

[Pojahn_M]

Oh, my ( and ) looks almost like { and } in my web browser.
Anyway, enums was not hard. I have looked through many examples and coded them myself. They are pretty simple and I understand them.
But I cant think of many uses(except GUI buttons). Perhaps because I dont know everything in java yet.
Can someone give me a list of examples were enums are useful?

[Fubarable]

Any place where you'd use several constants, substitute an enum.

[sunde887]

private static enum PlayerClass{
		//The class representations
		MAGE("Mage", 		14, 12, 10, 10, 7, 5, 2, 2, Element.ACID),
		PRIEST("Priest", 	13, 13, 10, 10, 6, 6, 2, 2, Element.WATER),
		WARRIOR("Warrior", 	10, 14, 10, 12, 3, 7, 3, 3, Element.EARTH),
		ROGUE("Rogue", 		10, 10, 22, 10, 1, 3, 9, 3, Element.LIGHTNING),
		HUNTER("Hunter", 	10, 11, 14, 11, 2, 5, 6, 3, Element.AIR),
		DRUID("Druid", 		10, 10, 12, 14, 1, 5, 3, 7, Element.FIRE);
		
		//The name of the class
		private String className;
	
		//Base stats of the class
		private int baseStamina;
		private int baseIntellect;
		private int baseStrength;
		private int baseAgility;
	
		//bonus stats gained per level of the class
		private int bonusIntellect;
		private int bonusStamina;
		private int bonusAgility;
		private int bonusStrength;
	
		//The type of the assigned class
		private Element type;
	
	
		private PlayerClass(String className, int baseIntellect, int baseStamina, int baseAgility, int baseStrength,
							int bonusIntellect, int bonusStamina, int bonusAgility, int bonusStrength, Element type
							){
			this.className = className;
			this.type = type;
			this.baseIntellect = baseIntellect;
			this.baseStamina = baseStamina;
			this.baseAgility = baseAgility;
			this.baseStrength = baseStrength;
			this.bonusIntellect = bonusIntellect;
			this.bonusStamina = bonusStamina;
			this.bonusAgility = bonusAgility;
			this.bonusStrength = bonusStrength;		
		}
	}

public static Player newMage(String name){ return new Player(name, PlayerClass.MAGE, Race.HUMAN, Sex.MALE); }
	public static Player newPriest(String name){ return new Player(name, PlayerClass.PRIEST, Race.HUMAN, Sex.MALE); }
	public static Player newDruid(String name){ return new Player(name, PlayerClass.DRUID, Race.HUMAN, Sex.MALE); }
	public static Player newRogue(String name){ return new Player(name, PlayerClass.ROGUE, Race.HUMAN, Sex.FEMALE); }
	public static Player newHunter(String name){ return new Player(name, PlayerClass.HUNTER, Race.HUMAN, Sex.MALE); }
	public static Player newWarrior(String name){ return new Player(name, PlayerClass.WARRIOR, Race.HUMAN, Sex.MALE); }

Is something recent where they use of enums were helpful.