Name of enum object in all lower-case

[Sandra Bachan]

Modification to Sierra/Bates, Chapter 3, Question 7.

Please note line 14 where Suits.SPADES automatically prints the name of the enum.

Question 1: Is this an in-built function of the enum?

Question 2: How do I implement toString() such that is prints the name of the Suits object in all lower-case. I attempted this in line 9, but in vain.

public class Bridge{
	public enum Suits{
		CLUBS(20), DIAMONDS(20), HEARTS(30), SPADES(30),
		NOTRUMP(40){public int getBidValue(int bid){
				return((bid-1)*30)+40; }};
		Suits(int points){this.points=points;}
		private int points;
		public int getBidValue(int bid){return points*bid;}
		public String toString(){ return Suits.this.tolower();}
	}
	public static void main(String[] args){
		System.out.println(Suits.NOTRUMP.getBidValue(3));
		System.out.println(Suits.HEARTS.getBidValue(3));
		System.out.println(Suits.SPADES + " " + Suits.SPADES.points);
		System.out.println(Suits.values());
		Suits[] s = Suits.values();
		for (Suits i: s)
			System.out.println(i);
	}
}

[Bear Bibeault]

Have you checked the API for java.lang.Enum for something that might help you?

[Sandra Bachan]

Just looked at it.

Even though it advises AGAINST overwriting toString(), I would like to know how to do it anyway (to study for the SCJP exam).

Would like it such that the name of the Suits object prints lower-case.

[Bear Bibeault]

Sandra Bachan wrote:Just looked at it.

And you saw nothing that might be helpful?

[Abimaran Kugathasan]

BTW, where is your tolower() method?

[Sandra Bachan]

@Bear: I'm still looking at the API, trying to figure out anything that may help

@Abimaran: tolower() is on line 9

[Ankit Garg]

Sandra, Abimaran is asking where have you declared tolower method in your enum. Its not a built in method for enums. There are 10 methods in java.lang.Enum class, one of them returns the name of the enum i.e. if we declare our enum as SPADE, that method will return "SPADE", you can convert it to lower case once you have the enum name as a String...

[Vicky Mehta]

Sandra Bachan wrote:Modification to Sierra/Bates, Chapter 3, Question 7.

Please note line 14 where Suits.SPADES automatically prints the name of the enum.

Question 1: Is this an in-built function of the enum?

Question 2: How do I implement toString() such that is prints the name of the Suits object in all lower-case. I attempted this in line 9, but in vain.

public class Bridge{
	public enum Suits{
		CLUBS(20), DIAMONDS(20), HEARTS(30), SPADES(30),
		NOTRUMP(40){public int getBidValue(int bid){
				return((bid-1)*30)+40; }};
		Suits(int points){this.points=points;}
		private int points;
		public int getBidValue(int bid){return points*bid;}
		public String toString(){ return Suits.this.tolower();}
	}
	public static void main(String[] args){
		System.out.println(Suits.NOTRUMP.getBidValue(3));
		System.out.println(Suits.HEARTS.getBidValue(3));
		System.out.println(Suits.SPADES + " " + Suits.SPADES.points);
		System.out.println(Suits.values());
		Suits[] s = Suits.values();
		for (Suits i: s)
			System.out.println(i);
	}
}

AFAIK
1) Suits.SPADES is an Enum Constant.
An Enum constant is internally a a final static reference of the Enum Type Suits.
When Suits.SPADES is referred to in the function System.out.println, toString() function of this reference will be invoked.
Default toString() function of the Enum class invokes the name() function of the Enum class which returns the constant name as declared in the enum.

2) Replacing toString() function in this code to the code below would give you the desired result:
public String toString(){ return name().toLowerCase();}
This invokes the same name() function as mentioned above followed by toLowerCase() function of the String class.

[Sandra Bachan]

@Vicky: I updated the code and it now works.

public class Bridge{
	public enum Suits{
		CLUBS(20), DIAMONDS(20), HEARTS(30), SPADES(30),
		NOTRUMP(40){public int getBidValue(int bid){
				return((bid-1)*30)+40; }};
		Suits(int points){this.points=points;}
		private int points;
		public int getBidValue(int bid){return points*bid;}
		public String toString(){ return name().toLowerCase();}
	}
	public static void main(String[] args){
		System.out.println(Suits.NOTRUMP.getBidValue(3));
		System.out.println(Suits.HEARTS.getBidValue(3));
		System.out.println(Suits.SPADES + " " + Suits.SPADES.points);
		System.out.println(Suits.values());
		Suits[] s = Suits.values();
		for (Suits i: s)
			System.out.println(i);
	}
}

@ All: Guess I need to practice UNDERSTANDING an API :-)


Thanks!!!

[Bear Bibeault]

"Practice makes perfect" which is why I sent you to the API instead of just blurting out the answer.

[Abimaran Kugathasan]

Ankit Garg wrote:Sandra, Abimaran is asking where have you declared tolower method in your enum. Its not a built in method for enums. There are 10 methods in java.lang.Enum class, one of them returns the name of the enum i.e. if we declare our enum as SPADE, that method will return "SPADE", you can convert it to lower case once you have the enum name as a String...

Oh! Sorry, I misunderstood the question!

[John Avila]

Now i have a question, it sure does seem like

System.out.println(Suits.SPADES + " " + Suits.SPADES.points);

shouldn't be accessible because it is private.

I suppose this is because enums are "special" and is part of the bridge class?

[Bear Bibeault]

Nothing "special"... it acts just like any other inner class.

[Abimaran Kugathasan]

Myname Is wrote:
shouldn't be accessible because it is private.

I suppose this is because enums are "special" and is part of the bridge class?

Try this...

class Test	{
	class XA	{
		private int x = 9;
	}
	public void method()	{
		System.out.println(new XA().x);
	}
}

[John Avila]

You're right thanks.
Not sure why i didn't think of that.