Java Reference
In-Depth Information
There's a lot more gunk in there than we've seen up to now. First of all, I've
called our new list
myPlayerList
. Note that funny syntax with the angle brackets,
<
and
>
. You have to specify the kind of list you're making (twice, in fact).
Java 7 improves on this a little; you don't have to repeat it on the right-hand
side and you can say
List<Player>whatever=newArrayList<>()
. Also, in a small bit
of weirdness, notice that although it's
List
on the left, it's
ArrayList
on the right.
The reason for that is…because Java. (Okay, the reason is that
List
is the
parent and
ArrayList
is one particular child.) Moving on now.
2
With a list you've created, you can do a lot of fun things, like adding and
removing values from the list, retrieving values, and checking to see if a value
exists. Here's a bit of sample code:
public void
listDemo(Player me) {
List
<
String
> listOfStrings =
new ArrayList
<
String
>();
❶
❷
listOfStrings.add(
"This"
);
listOfStrings.add(
"is"
);
listOfStrings.add(
"a"
);
listOfStrings.add(
"list."
);
❸
String
third = listOfStrings.get(2);
me.chat(
"The third element is "
+ third);
❹
me.chat(
"List contains "
+ listOfStrings.size() +
" elements."
);
❺
listOfStrings.add(3,
"fancy"
);
❻
boolean
hasIt = listOfStrings.contains(
"is"
);
me.chat(
"Does list contain the word 'is'? "
+ hasIt);
hasIt = listOfStrings.contains(
"kerfluffle"
);
me.chat(
"Does the list contain the word 'kerfluffle'? "
+ hasIt);
// Print out each value in the list
for
(
String
value : listOfStrings) {
me.chat(value);
}
❼
listOfStrings.clear();
me.chat(
"Now it's cleared out, size is "
+ listOfStrings.size());
hasIt = listOfStrings.contains(
"is"
);
me.chat(
"List contains the word 'is' now is "
+ hasIt);
}
2. “Because Java” is a bit of an Internet joke; see
http://www.theatlantic.com/technology/archive/
