java training

trainer
1. Ihar Blinou
schedule
1. 9:00 - 16:00
2. dinner
  1. 14:00 - 15:00
contents
1. main concepts
2. exceptions
3. jdbc
4. xml
5. collections
6. multithreading
7. networking
books
1. java code conventions
2. core java
  1. horstman
  2. полный справочник
3. code complete
4. java philosophy
  1. eckel
5. java - промышленное программирование
6. refactoring to patterns
resources
1. http://tutorials.jenkov.com
2. http://java2s.com
features
1. no functions, only methods
  1. all functions are inline
2. everything is a class
3. every language construct in a separate file
4. there should be no two public classes in one file
5. static method cannot be virtual
6. all classes are in package
  1. there is default package
7. every object is passed via reference
8. == vs equals
9. oop principle obtrusion
  1. serialization/deserialization
10. deep cloning
  1. horstman
11. case sensitive
12. str to num
  1. Integer.parseInt
  2. Integer.valueOf
  3. Integer.decode
  4. new Integer
questions
1. @override and other annotations
2. code inspections
  1. jlint
  2. pmd
  3. checkstyle
3. copying objects
4. why do we need static import?
5. casting/conversion
  1. classes
  2. interfaces
  3. arrays
6. constructors are not inherited
  1. ??
7. are arrays serializable?
8. instanceof vs getClass
code conventions
1. methods
2. classes
3. constants
4. packages
design patterns
1. GOF
  1. types
    1. creational
      1. singleton
      2. assumes only one (or limited) instance(s) of specific class
      3. factory
      4. factory creates objects of different subclasses using similar approach
      5. abstract factory
      6. factory method
      7. builder
      8. builder creates one large object
      9. prototype
    2. structural
      1. composite
      2. used for hierarchical data representation (fs tree, xml, categories, syntax parser, matryoshka doll etc)
      3. features
      4. recursive composition
      5. allows treat both individual objects and their clusters uniformly
      6. examples
      7. fs tree
      8. xml
      9. categories
      10. syntax parser
      11. AST
      12. matryoshka doll
      13. hierarchies
      14. church
      15. military
      16. aristocratic
      17. administrative
      18. genres
      19. art
      20. music
      21. compexity classes
      22. decorator
      23. wrapper is the synonym of decorator
      24. facade
      25. provides interface for the more complex architecture
      26. flyweight
      27. proxy
      28. bridge
      29. features
      30. run-time binding implementation
      31. hierarchies are being implemented independently
      32. decoupling abstraction from implementation
      33. example
      34. different implementations for different platforms
      35. adapter
      36. matches interfaces of different classes
      37. features
      38. legacy classes have replacements
      39. decorator provides enhanced interface
      40. facade defines new interface while adapter reuses the old one
    3. behavioral
      1. command
      2. observer/listener
      3. chain of responsibility
      4. iterator
      5. mediator
      6. memento
      7. imitates ctrl+z behavior
      8. often used in a tandem with a command pattern
      9. state
      10. strategy
      11. template method
      12. visitor
2. GRASP
  1. knowledge classes
  2. action classes
  3. patterns
    1. expert
    2. high cohesion
    3. glaukap ??
3. examples
  1. http://fluffycat.com
language
1. errors handling
  1. exceptions
    1. try-catch-finally
      1. finally
      2. used for
      3. db connection close
      4. close files
      5. release other allocated resources
    2. throw
    3. throws
    4. types
      1. checked
      2. throws
      3. Exception
      4. unchecked
      5. RuntimeException
    5. multiple catch blocks
      1. two catches cannot handle exception
    6. catch(Exception e)
      1. deprecated!
    7. redefine constructor in order to be able passing error message
    8. all exceptions implement interface Throwable
    9. classes
      1. IOException
      2. NullPointerException
      3. ArithmeticException
      4. CloneNotSupportedException
    10. inheritance
      1. subclass methods should throw subexceptions which overridden method throws
      2. narrowing approach
      3. subclass constructor should throw all exceptions (or its parent classes) parent constructor throws
      4. widening approach
  2. errors
    1. OutOfMemoryError
    2. StackOverflowError
    3. program is allowed to terminate
  3. assertions
    1. assert <condition>:<expression>;
2. JavaBeans
  1. public contstructor
    1. for possibility of creation via reflection
  2. implements Serializable
  3. private fields
  4. setters/getters
  5. concept
    1. object as a single information domain
3. types
  1. base types
    1. boolean
      1. Boolean
      2. booleanValue
      3. parseBoolean
    2. byte
      1. Byte
      2. byteValue
      3. parseByte
    3. char
      1. Character
      2. charValue
      3. ----
    4. short
      1. Short
      2. shortValue
      3. parseShort
    5. int
      1. Integer
      2. intValue
      3. parseInt
    6. long
      1. Long
      2. longValue
      3. parseLong
    7. float
      1. Float
      2. floatValue
      3. parseFloat
    8. double
      1. Double
      2. doubleValue
      3. parseDouble
    9. valueOf
  2. primitive
    1. byte
      1. 1
    2. short
      1. 2
    3. int
      1. 4
    4. long
      1. 8
    5. float
      1. 4
    6. double
      1. default
      2. 8
    7. char
      1. 2
    8. bool
    9. arithmetic promotion (implicit)
      1. long
      2. char
      3. int
      4. short
      5. byte
      6. float
      7. double
4. literals
  1. number
    1. int
      1. 10
      2. 012
      3. 0xA
    2. float/double
      1. 1.0001
      2. 5.3e-3
      3. 6.89e-8f
  2. chars
    1. \u0004
    2. 'a'
    3. escape sequence
      1. \n
      2. \r
      3. \t
      4. \b
      5. \f
      6. \'
      7. \"
      8. \\
  3. null
  4. boolean
    1. true
    2. false
  5. NaN
5. variables
  1. types
    1. local
    2. static
    3. instance
6. comments
  1. javadoc
    1. @
      1. author
      2. version
      3. exception
      4. param
      5. return
      6. deprecated
      7. since
      8. throws
      9. see
      10. ...
  2. one line
    1. //
  3. multiline
    1. /* */
7. operators
  1. relative
    1. !=
    2. <=
    3. >=
    4. >
  2. other
    1. ==
      1. &
      2. ^
      3. *
      4. |
      5. &&
      6. ||
      7. ? :
      8. =
  3. arithmetic
    1. +
    2. ++
    3. -
    4. --
    5. *
    6. /
    7. %
      1. remainder
  4. logical
  5. bitwise
  6. assignment
  7. flow
    1. switch/case
      1. does not accept long ??
    2. for
    3. while
    4. do
    5. continue
    6. break
  8. advanced
    1. []
    2. ? :
    3. .
    4. ()
      1. casting
      2. params list
    5. new
    6. instanceof
      1. returns true for
      2. class
      3. or its subclass
      4. 'a instanceof Object' always returns true
      5. except 'null instanceof Object';
8. oop
  1. constructors
    1. default constructor is used when explicit constructor is absent
    2. overloading
    3. not always default constructor is reasonable
    4. constructor is
      1. the class method without return value
    5. are not inherited
  2. inheritance
    1. all methods and fields are inherited to subclass
    2. logical blocks are not inherited
    3. default class is being Object inherited
    4. fields are not overridden even though they are being inherited
      1. there might be id field in both parent and subclass
  3. incapsulation
    1. access modifiers
      1. private
      2. protected
      3. default (private-package)
      4. public
  4. polymorphism
    1. types
      1. static
      2. templates
      3. template methods
      4. overloading
      5. generics
      6. ?
      7. dynamic
      8. late binding
      9. overriding
      10. method visibility should be widened, not narrowed
    2. ability of change reference depending on the passed object type
    3. polymorphic substitution
      1. static + dynamic = combined polymorphism
      2. sublass reference cannot be initialized with superclass object
  5. relationships
    1. is-a
    2. has-a
  6. modifiers
    1. abstract
    2. final
    3. static
    4. transient
    5. native
    6. synchronized
    7. volatile
    8. private
    9. public
    10. protected
  7. classes
    1. abstract
    2. inner
      1. 1 to 1 classes relationship
      2. used for
      3. unique concept existing only in the scope of the outer class
      4. compound data types
      5. Enum declarations
      6. outer class cannot see fields and methods of inner class if there is no instance
      7. inner class sees all, even private
      8. access to outer class instance
      9. Outer.this.field
      10. subclass of inner class loses access to the outer class
      11. though subclasses of inner and outer keep accessibility rules
    3. nested
      1. static inner class
      2. can be created without instantiation of outer class
      3. static keyword before inner class definition describes instantiation approach. it tells nothing about fields and methods
      4. new Outer.Inner()
      5. no instance of outer class required
      6. inner classes of interfaces are static by default
      7. can imitate methods implementation inside the interface
    4. anonymous
      1. example
      2. AnonClass anon = new AnonClass { ... }
      3. inherited from the class where it is defined
      4. often used in enums
      5. in case of abstract method definition in enum it is required to override it with anon class in each enum value
      6. it is not allowed to inherit from enum
  8. interfaces
    1. names
      1. -able
      2. Serializable
      3. -or
      4. Iterator
    2. should represent complex actions
    3. can have details of implementation
    4. can inerit from each other
      1. extends keyword
    5. interfaces parametrization
    6. vs abstract classes
      1. it is useful to parametrize interface with the abstract class
      2. interface Interface<T extends AbstractClass>
      3. common
      4. cannot create objects
      5. unimplemented methods
      6. difference
      7. class has
      8. fields
      9. methods
      10. constructor
      11. abstract
      12. reasonable when there are
      13. common fields
      14. common methods implementation
      15. single inheritance
      16. can have default implementation
      17. interface
      18. just a list of methods
      19. multiple inheritance
  9. super
    1. super(a, b, c)
    2. super.method()
    3. each constructor of inherited class has implicit super() call without params
  10. this
    1. this(a, b, c)
      1. chain constructor
    2. this.method()
9. import
  1. static
    1. import static java.util.Math.*
  2. java.util.* is imported by default
10. types
  1. numeric
    1. Number
      1. Byte
      2. Short
      3. Integer
      4. Long
      5. BigInteger
      6. BigDecimal
      7. Float
      8. Double
  2. String
    1. immutable
    2. if literal is the same, reference also the same
      1. String s1 = "Java"
      2. String s2 = "Java"
      3. String s3 = "Ja" + "va"
    3. methods
      1. concat
      2. individual chars
      3. charAt
      4. comparison
      5. compareTo
      6. compareToIgnoreCase
      7. equals
      8. equalsIgnoreCase
      9. contentsEqualsTo
      10. substring search
      11. startsWith
      12. endsWith
      13. indexOf
      14. lastIndexOf
      15. substring
      16. extract substring
      17. uppercased string
      18. toUpperCase
      19. lowercase string
      20. toLowerCase
      21. length
      22. replace
      23. trim
      24. toString
      25. valueOf
      26. intern
      27. String s1 = "Java"
      28. String s2 = new String("Java")
      29. s1 == s2 -> false
      30. s2 = s1.intern()
      31. s1 == s2 -> true
      32. isEmpty
      33. added in java 6
      34. format
      35. split
    4. buffers
      1. StringBuffer
      2. modifiable strings
      3. append
      4. insert
      5. reverse
      6. setCharAt
      7. deleteCharAt
      8. setLength
      9. toString
      10. StringBuilder
      11. unsynchronized StringBuffer
      12. hashCode and equals are not overridden for both classes
    5. Locale class
      1. getCountry
      2. getDisplayCountry
      3. getLanguage
      4. getDisplayLanguage
      5. ...
    6. regexes
      1. Pattern class
      2. compile
      3. matches
      4. matcher
      5. split
      6. toString
    7. formatting
      1. numbers
      2. dates
      3. currency
      4. Formatter class
      5. close
      6. flush
      7. format
      8. toString
      9. %[<argumentIndex>$][<flags>][<width>][.<precision>] <type>
      10. types
      11. %b
      12. Boolean
      13. %c
      14. Character
      15. %d
      16. Decimal
      17. %f
      18. Floating point
      19. %s
      20. String
    8. parsing
      1. Scanner class
    9. all related classes are final
  3. arrays
    1. cannot convert into each other
    2. arrays array
      1. references array
    3. definition
      1. {}
  4. enums
  5. generics
    1. ?
      1. anonymous type
    2. T
      1. type
    3. can use 'extends' keyword
    4. can not
      1. generic constructor can not be instantiated
      2. be used in static methods
11. logical blocks
  1. types
    1. default
      1. run on class initialization
    2. static
      1. run on class loading
  2. run only once
12. methods
  1. variable params
    1. method(String s, int ... k)
    2. method(String ... s)
    3. method(Object ... o)
    4. method(int ... k)
      1. method(1, 2, 3, 4)
    5. method(String[] ... arr)
    6. should be at the end
    7. works with both params list and arrays
13. autoboxing/unboxing
  1. Integer num = 170
    1. object creation + boxing
  2. Integer k = ++num
    1. unboxing + operation + object creation + boxing
  3. int i = k
    1. unboxing
  4. Integer i = null
  5. int j = i
  6. dynamic comparison
    1. unboxing, comparison, boxing
  7. Float f = new Float("7")
14. serialization
  1. implements Serializable
  2. requires serialVersionUID
  3. transient
    1. cannot be serialized
      1. as well as static fields
15. collections
  1. hierarchy
    1. Map
      1. SortedMap
      2. AbstractMap
      3. TreeMap
      4. HashMap
      5. LinkedHashMap
      6. EnumMap
      7. WeekHashMap
      8. Subtopic 1
      9. IdentityHashMap
      10. allow duplicated keys
      11. System.identityHashCode()
      12. Hashtable
    2. Collection
      1. List
      2. AbstractCollection
      3. AbstractList
      4. ArrayList
      5. AbstractSequenceList
      6. LinkedList
      7. Vector
      8. Stack
      9. AbstractQueue
      10. PriorityQueue
      11. ArrayDeque
      12. AbstractSet
      13. TreeSet
      14. HashSet
      15. LinkedHashSet
      16. EnumSet
      17. Set
      18. NavigableSet
      19. SortedSet
      20. Queue
      21. Deque
      22. ArrayDeque
  2. thread-safety
    1. java 1
      1. all thread-safety
    2. java 2
      1. emerged non thread-safety
  3. methods
    1. Collection
      1. add
      2. addAll
      3. clear
      4. equals
      5. isEmpty
      6. iterator
      7. remove
      8. size
      9. Queue
      10. element
      11. remove
      12. offer
      13. peek
      14. poll
    2. List
      1. indexOf
      2. add
      3. addAll
      4. get
      5. remove
      6. set
      7. subList
      8. LinkedList
      9. addFirst
      10. addLast
      11. getFirst
      12. getLast
      13. removeFirst
      14. removeLast
      15. removeFirstOccurence
      16. removeLastOccurence
    3. Comparator
      1. compare
      2. sort
    4. Comparable
      1. compareTo
    5. TreeSet
      1. first
      2. last
      3. subSet
      4. tailSet
      5. headSet
      6. comparator
    6. EnumSet
      1. noneOf
      2. of
      3. complementOf
      4. range
    7. Map
      1. containsKey
      2. containsValue
      3. entrySet
      4. keySet
      5. get
      6. put
      7. putAll
      8. remove
      9. values
    8. Map.Entry
      1. getKey
      2. getValue
      3. setValue
  4. auxillary interfaces
    1. Iterator<T>
      1. reference to the next element
      2. methods
      3. hasNext
      4. next
      5. remove
    2. Comparator<T>
    3. Map.Entry
    4. Enumeration<T>
      1. methods
      2. elements
      3. keys
  5. auxillary classes
    1. Collections
      1. static class with static methods for actions with collections
      2. methods
      3. checkedCollection
      4. addAll
      5. copy
      6. disjoint
      7. emptyList
      8. fill
      9. frequency
      10. max
      11. min
      12. nCopies
      13. replaceAll
      14. reverse
      15. rotate
      16. shuffle
      17. singletonMap
      18. sort
      19. swap
    2. Arrays
      1. class for manipulation with arrays
      2. methods
      3. fill
      4. sort
      5. copyOf
      6. copyOfRange
      7. asList
  6. foreach
    1. is applicable on classes implementing Iterable interface
  7. TreeSet cannot be parameterized with StringBuilder or StringBuffer
    1. because those classes do not have compareTo implemented
  8. how to make java 1.4 collection type-safe?
    1. checkedCollection method
16. multithreading
  1. application has at least one thread: main
    1. it waits until all spawned thread will be terminated
  2. class Thread
    1. methods
      1. run
    2. throws InterruptedException
  3. interface Runnable
    1. methods
      1. run
      2. start
  4. thread
    1. states
      1. new
      2. ready/runnable
      3. running
      4. non-runnable
      5. sleeping
      6. time waiting
      7. blocked
      8. state becomes active on synchronization
      9. waiting
      10. wait
      11. is called on non-runnable thread
      12. stops thread
      13. releases object block
      14. object becomes available
      15. notify
      16. makes thread ready
      17. notifyAll
      18. all waiting threads are notified to be ready
      19. it is not recommended to kill/terminate/interrupt thread from non-runnable state
      20. dead/terminated
      21. class State
    2. priorities
      1. MIN
      2. MAX
      3. NORM
  5. groups
    1. ThreadGroup class
  6. control
    1. yield
    2. join
      1. ?
    3. close
  7. daemons
    1. isDaemon
    2. setDaemon
  8. synchronization
    1. thread-safety of
      1. file
      2. object
      3. thread
    2. it is not required for writing/reading
      1. except 64bit platform
  9. semaphors
    1. restrict the number of threads than can access some (physical or logical) resource
  10. core
    1. java.util.concurrent.*
      1. ConcurrentHashMap
      2. CopyOnWriteArrayList
      3. Executor
      4. AtomicInteger
      5. AtomicLong
      6. AtomicReference
      7. SynchronizedInt
      8. Semaphore
      9. CyclicBarrier
      10. Exchanger
17. core
  1. IO
    1. java.io.File class
    2. streams
      1. low-level
      2. FileInputStream
      3. FileOutputStream
      4. ObjectInputStream
      5. ObjectOutputStream
      6. high-level
      7. DataInputStream
      8. DataOutputStream
    3. readers
      1. low-level
      2. FileReader
      3. high-level
      4. BufferedReader
      5. file
      6. socket
      7. readline
    4. writers
      1. low-level
      2. FileWriter
      3. high-level
      4. BufferedWriter
      5. PrintWriter
  2. Random
    1. java.util.Random
  3. Object
    1. clone
      1. class should implement Cloneable interface
      2. if interface is not implemented, then CloneNotSupportedException will be raised
      3. approach
      4. deep
      5. example is in the book by Horstman
      6. shallow
      7. super.clone()
      8. immutable objects are cloned automatically
    2. hashCode
      1. implementation should try to map object and unique hash code
    3. equals
      1. equals assumes that two equal objects have the same hash codes
      2. Effective Java describes how to violate equivalence criteria
      3. consists of
      4. null check
      5. objects classes check
      6. object casting
      7. object properties null check
      8. object properties comparison
    4. toString
    5. getClass
      1. part of the the reflection mechanizm
    6. finalize
      1. Effective Java describes the way how to halt the system with finalize overriding
    7. threading
      1. notify
      2. notifyAll
      3. wait
  4. ResourceBundle
  5. Properties
  6. console
    1. System.console()
    2. console.readPassword()
  7. Scanner
  8. zip
  9. jar
jdbc
1. concepts
  1. result sets
  2. queries
    1. run on the statement instance
    2. CRUD
      1. create
      2. st.executeUpdate("INSERT employee VALUES(" + 13 + "," + "'Aman'" + ")");
      3. retrieve
      4. udpate
      5. delete
    3. example
  3. statements
    1. example
      1. Statement st = connection.createStatement()
    2. types
      1. prepared
      2. PreparedStatement
      3. executeBatch
      4. callable
      5. CallableStatement
      6. for stored procedures
  4. drivers
    1. driver should be loaded into memory
      1. Class.forName(driverName)
      2. new com.mysql.jdbc.Driver()
  5. metadata
    1. used to work with table and db structure
    2. interfaces
      1. ResultSetMetaData
      2. methods
      3. getColumnCount
      4. getColumnName
      5. getColumnType
      6. DatabaseMetaData
      7. methods
      8. getDatabaseProductName
      9. getDatabaseProductVersion
      10. getDriverName
      11. getUserName
      12. getURL
      13. getTables
    3. example
      1. ResultSetMetaData md = resultSet.getMetaData()
      2. DatabaseMetaData md = connection.getMetaData()
  6. connections
    1. example
      1. Connection.getConnection("jdbc:mysql://localhost:3306/mydb")
    2. uses specific connection syntax
      1. jdbc:[dbtype]://[host]:[port]/[dbname]
    3. surely should be closed
    4. connection creation is really expensive
    5. pools
      1. in connection pools connections are placed into the list (pool) in order to store expensive connections and allow users to use them
  7. DAO
    1. Data Access Object pattern
log4j
1. appender
  1. console
  2. files
  3. gui
  4. jms
  5. sockets
  6. event loggers
  7. syslog
2. levels
  1. TRACE
  2. DEBUG
  3. INFO
  4. WARN
  5. ERROR
  6. FATAL
3. rotation
  1. every N hours/days/... new file is being created
4. layouts
5. custom filters
jUnit
1. test cases
2. fixtures
  1. @Before
  2. @After
  3. @Test
  4. @BeforeClass
3. suites
4. assertions
5. exceptions handling
  1. @Test(expected=Exception.class)
6. parameterized test
7. timeout test
networking
1. classes
  1. Socket
    1. example
      1. Socket sock = new Socket(host, port)
      2. Socket sock = new ServerSocket(port)
  2. InetAddress
  3. DatagramSocket
2. auxillary classes usage
  1. BufferedReader
  2. InputStreamReader
  3. PrintStream
tasks
1. lesson 1
  1. chapter 3,4
  2. implementation of factory and/or command
2. lesson 3
  1. composite + builder
  2. bridge
  3. composite + bridge
3. lesson 4
  1. ResourceBundle
4. lesson 5
  1. implement some specific domain
    1. airplanes
    2. books
    3. musicshop
    4. ...
    5. entity classes with code conventions
  2. use DB
    1. connection pool
    2. data source
  3. add functionality of filtration/search and adding/deletion to the db
  4. collections + generics
  5. patterns
    1. DAO
    2. Command
    3. Memento
    4. View/Controller
    5. Factory
    6. Singleton
    7. ...
  6. resource bundle
    1. db properties
  7. log4j
  8. junit
  9. multithreading
  10. command line interaction
virtual machine
1. garbage collector
  1. System.gc()
  2. Runtime.getRuntime().gc()
  3. System.runFinalization()
XML
1. xerces
2. org.w3c.*
3. org.xml.*
BookLibrary application
1. 0.x.1
  1. factory pattern
  2. singleton pattern
  3. command pattern
2. 0.x.2
  1. patterns
    1. factory
    2. singleton
    3. command
    4. memento
    5. dao
    6. composite
  2. usage
    1. db
      1. filtration
      2. by title
      3. by id
    2. resource bundle
    3. collections
      1. arraylist
    4. enum
3. 0.x.3
  1. improvements
    1. add some pattern
      1. bridge
      2. builder
      3. strategy
      4. listener
    2. add interactivity
      1. vim-like input
    3. modify factory to create instances of proper classes
    4. logger