Download The AP Java Subset

The AP Java Subset
Topics
A Topics
Primitive Types
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int
double
boolean
Operators
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+, -, *, /, %
++, -=
+=, -=, *=, /=, %=
==, !=, <, >, <=, >=
&&, ||, !
Numeric Casts
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(int)
(double)
String Concatenation
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+
will convert numbers to strings and invoke
the toString() method on objects
Escape Sequences
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\\
\”
\n
Input & Output
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INPUT IS NOT TESTED
Output is restricted to System.out.print and
println
Formatting output is not tested
Arrays
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One-dimensional
Arrays of primitive types & of objects
Initialization of named arrays:
–
int[] array = {1, 3, 6, 9};
Control Structures
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if
if/else
while
for
return
(do/while, switch, continue, break – not
tested)
Method Overloading
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Understand signature of method
Depends on number, types & order of
parameters
Does not depend on return type of method
Classes
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Construct objects with new operator
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Supply constructor parameters
Invoke accessor & modifier methods
Modify existing classes
Design own classes
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Visibility
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All classes will be public
All instance variable will be private
Methods, constructors and constants are
either public or private
NO protected
Comments
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// single line comments
/* */ block comments
No Javadoc comments
Final & Static
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final keyword is used for final block scope
constants
static final class scope constants
static methods
static final variables
NO – final parameters, final methods, final
classes, static variables
null & this
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null reference is in the Java subset
this is restricted to passing an implicit
parameter in its entirety to another method
(obj.method(this))
Descriptions such as “the implicit parameter
this”
Super
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Use to invoke superclass constructor
–
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ex: super(args);
Or to invoke superclass method
–
ex: super.method(args);
Constructors
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Be able to implement
Initialize all instance variables
Don’t need to know default rules
Extend & Implement
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extend classes
implement interfaces
Know inheritance!!!
Read and Understand
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Be able to read definitions of interfaces and
abstract classes
Understand that the abstract methods need
to be redefined for non-abstract classes
Write interfaces or class declarations when
given a general description of the interface or
class
Equals
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Know when to use == or .equals
Objects: equals
Identity: ==
Subclass to Superclass
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No casting is needed to convert from a
subclass to a superclass
Do need to know class casts:
–
–
ArrayList xx = new ArrayList();
yy = (yyclass)xx.get(i);
Packages
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import statement
import package.subpackage.class;
Exceptions
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NullPointerException
ArrayIndexOutOfBoundsException
ArithmeticException
ClassCastException
IllegalArgumentException
Standard Library Methods
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java.lang.Object
–
–
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java.lang.Comparable
–
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equals
toString
compareTo
java.lang.Integer
–
–
–
–
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Integer(int value) //constructor
intValue
equals
toString
compareTo
Standard Library Methods (cont’d)
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java.lang.Double
–
–
–
–
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Double(double value) //constructor
doubleValue
equals
toString
compareTo
java.lang.String
–
–
–
–
–
compareTo
equals
length
substring
indexOf
Standard Library Methods (cont’d)
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java.lang.Math
–
–
–
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abs (for int and double)
pow
sqrt
java.util.Random
–
–
nextInt
nextDouble
Standard Library Methods (cont’d)
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java.util.ArrayList
–
–
–
–
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size
add
get
set
remove
AB Topics
Two-dimensional Arrays
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Ragged arrays are not tested
–
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int [][] x = new int[3][];
Don’t need to know int[3][3] is an array of
arrays
Know that x[0].length is the number of
columns in a rectangular two-dimensional
array named x
Abstract Classes
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AB students are expected to design own
interfaces and abstract classes
Throwing Unchecked Exceptions
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IllegalStateException
NoSuchElementException
Standard Library Methods
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java.lang.Object
–
–
–
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java.lang.Comparable
–
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equals
toString
hashCode
compareTo
java.lang.Integer
–
–
–
–
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Integer(int value) //constructor
intValue
equals
toString
compareTo
Standard Library Methods (cont’d)
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java.lang.Double
–
–
–
–
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Double(double value) //constructor
doubleValue
equals
toString
compareTo
java.lang.String
–
–
–
–
–
compareTo
equals
length
substring
indexOf
Standard Library Methods (cont’d)
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java.lang.Math
–
–
–
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abs (for int and double)
pow
sqrt
java.util.Random
–
–
nextInt
nextDouble
Standard Library Methods (cont’d)
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java.util.List
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–
–
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add
size
get
set
iterator
listIterator
java.util.ArrayList
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All List methods
add
remove
Standard Library Methods (cont’d)
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java.util.LinkedList
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addFirst
addLast
getFirst
getLast
removeFirst
removeLast
Standard Library Methods (cont’d)
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java.util.Set
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add
contains
remove
size
iterator
java.util.HashSet
java.util.TreeSet
Standard Library Methods (cont’d)
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java.util.Map
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–
–
–
–
–
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put
get
remove
containsKey
size
keySet
java.util.HashMap
java.util.TreeMap
Standard Library Methods (cont’d)
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java.util.Iterator
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–
–
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hasNext
next
remove
Java.util.ListIterator
–
–
add
set
Online resources
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Acorn online
Java API