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