Object-Oriented Programming (Java)

Review 2014

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Unit 1 Class Design

• Basic Console I/O• StringTokenizer• Exception• UML class diagram

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Console I/O

• private static BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));

• private static PrintWriter stdOut = new PrintWriter(System.out, true);

• private static PrintWriter stdErr = new PrintWriter(System.err, true);

true, autoflush

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StringTokenizer

• Import java.util.*;

• StringTokenizer tokenizer = new StringTokenizer(data, "_");

• tokenizer.countTokens(); //number of tokens

• while(tokenizer.hasMoreTokens()) {String token = tokenizer.nextToken();

} // traverse each token

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Exception (checked/unchecked)

try { stdErr.print("Enter an integer > "); stdErr.flush(); // print without auto flush return Integer.parseInt(stdIn.readLine()); } catch (IOException ioe) { ioe.printStackTrace(); System.exit(1); // terminate the program} catch (NumberFormatException nfe) { stdErr.println("Invalid number format"); }

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UML class diagram (Inheritance/Association)

Dashed line: implements

Solid line: extends

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Unit 2 Class Implementation

• equals()/toString()• Vector/ArrayList• JDK 5

– Vector<String>– ArrayList<String>– For each loop (Iterable interface/iterator method)

• JUnit• Design Pattern

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Vector and Iterator

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methods defined in class Vector• Vector(). Constructs an empty collection. • int size(). Returns the number of objects in the collection. • boolean isEmpty(). Determines if there are no objects in the collection. • boolean contains(Object elem). Determines if the specified object is an element

of the collection (as determined by the method equals). • boolean add(E o). Appends the specified object to the end of the collection. • void add(int index, E element). Inserts the specified object at the specified index

position, shifting any subsequent elements to the right (adds one to their indices). • E get(int index). Returns the object at the specified position. • public E set(int index, E element). Replaces the element at the specified index

position with the specified object. • public boolean remove(Object o). Removes the first occurrence of the specified

object (using method equals), shifting any subsequent elements to the left (subtracts one from their indices).

• E remove(int index). Returns the object at the specified position after first removing it from the collection and shifting any subsequent elements to the left (subtracts one from their indices).

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Methods Defined in Class ArrayList

• ArrayList(). Constructs an empty collection. • int size(). Returns the number of objects in the collection. • boolean isEmpty(). Determines if there are no objects in the collection. • boolean contains(Object elem). Determines if the specified object is an

element of the collection (as determined by the method equals). • boolean add(E o). Appends the specified object to the end of the collection. • void add(int index, E element). Inserts the specified object at the specified

index position, shifting any subsequent elements to the right (adds one to their indices).

• E get(int index). Returns the object at the specified position. • public E set(int index, E element). Replaces the element at the specified index

position with the specified object. • public boolean remove(Object o). Removes the first occurrence of the

specified object (using method equals), shifting any subsequent elements to the left (subtracts one from their indices).

• E remove(int index). Returns the object at the specified position after first removing it from the collection and shifting any subsequent elements to the left (subtracts one from their indices).

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import java.util.*;public class Client { private String name; private Vector accounts; public Client(String initialName) { name = initialName; accounts = new Vector(); }

public void addAccount(BankAccount bankAccount) { accounts.add(bankAccount); }

public Iterator getAccountIterator() { return accounts.iterator(); }

public int getNumberOfAccounts() { return accounts.size(); }}

See: LibrarySystem

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JDK 5public class Client implements Iterable<BankAccount> {

…private Vector<BankAccount> accounts;

public Client(String initialName) {

accounts = new Vector<BankAccount>();}

public Iterator<BankAccount> iterator() { return accounts.iterator();

}…

}

for (BankAccount account : client) { totalBalance += account.getBalance(); }

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Creating a test class in JUnit• Define a subclass of TestCase

• Override the setUp() method to initialize object(s) under test.

• Override the tearDown() method to release object(s) under test.

• Define one or more public testXXX() methods that exercise the object(s) under test and assert expected results.

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JUnit Methods

• assertEquals(x, y) – Test passes if x and y are equal– x and y can be primitives or any type with an appropriate equals

method– Three argument versions exist for floating point numbers

• assertFalse(b) – Test passes if boolean value b is false• assertTrue(b) – Test passes if boolean value b is true• assertNull(o) – Test passes if object o is null• assertNotNull(o) – Test passes if object o is not null• assertSame(ox, oy) – Test passes if ox and oy refer to the

same object • assertNotSame(ox, oy) – Test passes if ox and oy do not

refer to the same object

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Design Pattern

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Singleton Pattern

Constructor private

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Strategy Pattern

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Decorator

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Observer

Unit 3Advanced Class Implementation

• 3.1 Input and Output Programming

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Abstract Classes

• InputStream & OutputStream• Reader & Writer

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Line-oriented I/O