The AP Java Subset Topics

A Topics

Primitive Types int double boolean

Operators +, -, *, /, % ++, -- = +=, -=, *=, /=, %= ==, !=,, = &&, ||, !

Numeric Casts (int) (double)

String Concatenation + will convert numbers to strings and invoke the toString() method on objects

Escape Sequences \\ \” \n

Input & Output INPUT IS NOT TESTED Output is restricted to System.out.print and println Formatting output is not tested

Arrays One-dimensional Arrays of primitive types & of objects Initialization of named arrays: – int[] array = {1, 3, 6, 9};

Control Structures if if/else while for return (do/while, switch, continue, break – not tested)

Method Overloading Understand signature of method Depends on number, types & order of parameters Does not depend on return type of method

Classes Construct objects with new operator Supply constructor parameters Invoke accessor & modifier methods Modify existing classes Design own classes

Visibility All classes will be public All instance variable will be private Methods, constructors and constants are either public or private NO protected

Comments // single line comments /* */ block comments No Javadoc comments

Final & Static 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 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 Use to invoke superclass constructor – ex: super(args); Or to invoke superclass method – ex: super.method(args);

Constructors Be able to implement Initialize all instance variables Don’t need to know default rules

Extend & Implement extend classes implement interfaces Know inheritance!!!

Read and Understand 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 Know when to use == or.equals Objects: equals Identity: ==

Subclass to Superclass 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 import statement import package.subpackage.class;

Exceptions NullPointerException ArrayIndexOutOfBoundsException ArithmeticException ClassCastException IllegalArgumentException

Standard Library Methods java.lang.Object – equals – toString java.lang.Comparable – compareTo java.lang.Integer – Integer(int value) //constructor – intValue – equals – toString – compareTo

Standard Library Methods (cont’d) java.lang.Double – Double(double value) //constructor – doubleValue – equals – toString – compareTo java.lang.String – compareTo – equals – length – substring – indexOf

Standard Library Methods (cont’d) java.lang.Math – abs (for int and double) – pow – sqrt java.util.Random – nextInt – nextDouble

Standard Library Methods (cont’d) java.util.ArrayList – size – add – get – set – remove

AB Topics

Two-dimensional Arrays Ragged arrays are not tested – 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 AB students are expected to design own interfaces and abstract classes

Throwing Unchecked Exceptions IllegalStateException NoSuchElementException

Standard Library Methods java.lang.Object – equals – toString – hashCode java.lang.Comparable – compareTo java.lang.Integer – Integer(int value) //constructor – intValue – equals – toString – compareTo

Standard Library Methods (cont’d) java.lang.Double – Double(double value) //constructor – doubleValue – equals – toString – compareTo java.lang.String – compareTo – equals – length – substring – indexOf

Standard Library Methods (cont’d) java.lang.Math – abs (for int and double) – pow – sqrt java.util.Random – nextInt – nextDouble

Standard Library Methods (cont’d) java.util.List – add – size – get – set – iterator – listIterator java.util.ArrayList – All List methods – add – remove

Standard Library Methods (cont’d) java.util.LinkedList – addFirst – addLast – getFirst – getLast – removeFirst – removeLast

Standard Library Methods (cont’d) java.util.Set – add – contains – remove – size – iterator java.util.HashSet java.util.TreeSet

Standard Library Methods (cont’d) java.util.Map – put – get – remove – containsKey – size – keySet java.util.HashMap java.util.TreeMap

Standard Library Methods (cont’d) java.util.Iterator – hasNext – next – remove Java.util.ListIterator – add – set

Online resources Acorn online Java API