Transcript Using the Java API

Using the Java API
http://java.sun.com/javase/6/docs/api/
27-Mar-16
Where’s the API?
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Overview
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General approach
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If you know the name of the package, click it in the
upper left panel; or click All Classes
Click on the class in the lower left panel
Scroll in the right pane to find the summary of the
field, method, or constructor you want
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Or just read the general description
For more information, click the link in the
summary to go to the detailed information
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The Packages panel
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Choose the package you are
interested in
Or, choose All Classes
Classes in java.lang are
automatically imported into
every program--you don’t have
to do it yourself
Old snapshots—but the format
hasn’t changed
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The Classes panel
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This panel shows both
classes and interfaces
We haven’t yet talked about
interfaces
Note that some classes have
names similar to primitive
types (Boolean, Byte,
Character)
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The links bar
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Overview is where you start out
Index is handy for looking up methods
Help is the obvious
If you don’t like frames, you can choose
NO FRAMES
Deprecated methods are those that have been
replaced by better methods and should not be used
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The main information area
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General description of the class
Field summary
Constructor summary
Method summary
Field detail
Constructor detail
Method detail
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In each case, the
“summary” is the first
sentence of the “detail”
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Reading the method descriptions I
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An example from the String class:
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public char charAt(int index)
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Returns the character at the specified index
public means accessible from anywhere
char is the return type
charAt is the name of the method
int is the type of parameter expected
index is just a suggestive name
Example use: char firstChar = myStr.charAt(0);
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Reading the method descriptions II
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Another example from the String class:
 public static String valueOf(int i)
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Returns the string representation of the int argument.
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public means accessible from anywhere
static means this is a class method (see use below)
String is the return type, and is a hyperlink
valueOf is the name of the method
int is the type of parameter expected
i is just a suggestive name
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Example use: String numeral = String.valueOf(m / n);
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How was this documentation produced?
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All Java documentation was produced by the javadoc
program from javadoc (or just doc) comments in the
source code
Your doc comments can be used in the same way to
produce professional-looking documentation
The Interface menu item in BlueJ does the same basic
thing as javadoc
 Like most things in BlueJ, fancy features have been
omitted in the interests of simplicity
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Value of the API
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Version
packages
classes
methods
Java 1.0
8
212
1545
Java 1.1
23
504
3851
Java 1.2
60
1781
15060
Java 1.3
77
2130
17158
Java 1.4
135
2738
?
Java 1.5 and 6 ?
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?
You can only learn a small fraction of these
When you learn the kinds of things that are in the API, and
learn to find your way around in it, you become a far more
effective and efficient programmer
A good craftsman knows his/her tools
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Where to find the API docs
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On the web:
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http://java.sun.com/javase/6/docs/api/
On your own computer (if you downloaded them):
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C:/ProgramFiles/Java/jdk1.6.0_01/docs/api/index.html
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The End
Regarding “The Inevitability of eBooks:”
“Did you ride a horse to work today? I didn’t. I'm sure plenty
of people swore they would never ride in or operate a
‘horseless carriage’—and they never did! And then they died.”
http://chrisyeh.blogspot.com/2009/02/and-then-they-died-inevitability-of.html
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