Basic Packages of Java

1
Basic Packages of Java
java.lang Package java.util Package java.io
Package
2
Package

• To group into one unit the classes or interfaces
  related each other
• Provide the package for classes or interfaces to
  be used frequently
• Basic Packages
• java.lang, java.util, java.io, java.net, java.awt
  

3
java.lang Package

• Included by Java Compiler without import
  statement
• Interfaces and Classes provided by java.lang
  package
• Table 12.1

4
java.lang Package

• Math Class
• Provide the methods and constants for the
  mathematic calculation
• Ex 12.1
• Runtime Class
• Methods to give the interfaces between program
  execution environment and programs
• Ex 12.2

5
java.lang Package

• Thread Class
• Class with methods for implementing the multi
  thread program
• ThreadGroup Class
• Class to deal with threads as a group
• Class class
• To give information about class or interface
  related to specific object

6
java.util Package

• Package to provide the useful utility class
• Provide the class to support various standard
  programming data structure
• Package Structure
• Table 12.2
• Hierarchical Structure of Package
• Fig 12.2

7
java.util Package

• Enumeration Interface
• Interface for dealing with the enumerated
  elements
• Ex 12.3
• BitSet Class
• Class to deal with bit set growing dynamically
• Ex 12.4
• Vector Class
• Class having the elements to be accessed through
  integer index as array
• Ex 12.5

8
java.util Package

• Stack Class
• Provide the methods to manage the stack
• Ex 12.6
• Hashtable Class
• Manage the Hashtable to store the data and search
  it using given key
• Ex 12.7
• Random Class
• To have the methods to generate the random number
  
• Ex 12.8

9
java.util Package

• StringTokenizer Class
• To give the methods to tokenize the given string
  by delimiter such as blank or specified string
• Ex 12.9
• Date Class
• Class with the methods related to data and time

10
java.io Package

• I/O Function based on Stream Class
• Carried out I/O independent on specific OS
• Abstract Class InputStream, OutputStream
• Hierarchical Structure of Class
• Fig 12.3
• Interfaces and Classes included in Package
• Table 12.3

11
java.io Package

• InputStream Class
• Super Class of all Input Stream Class
• Abstract Class to provide the basic methods
  related to input
• Ex 12.10
• OutputStream Class
• Abstract Class to give the basic methods related
  to output

12
java.io Package

• DataInputStream DataOutputStream Class
• Class to define the methods carrying out I/O to
  basic type
• Class implemented by being inherited from
  DataInput interface and DataOutput interface
• Methods regarding the data type which is related
  to input and output
• ? 12.4 ??

13
java.io Package

• PipedInputStream class PipedOutputStream class
• Class to use the output of one thread as the
  input of other thread
• BufferedInputStream BufferedOutputStream Class
• Place the buffer at the middle for I/O operation
  to avoid the direct access to I/O stream

PipedOutputStream Output new
PipedOutputStream() PipedInputStream Input
new PipedInputStream(Output)
14
java.io Package

• FileInputStream FileOutputStream Class
• FileInputStream Class
• To read the data from file
• If cannot open file, Throw FileNotFoundException
• FileOutputStream Class
• To write the data to file
• Ex 12.11
• FilterInputStream FilterOutputStream Class
• Give the methods to modify the data additionally
  when read/write the data

15
java.io Package

• ByteArrayInputStream ByteArrayOutputStream
  Class
• Class to use the byte array as input object of
  input stream or output object of output stream
• Not to be blocked unlike other I/O streams
• Ex 12.12
• PrintStream Class
• To output the data as text form, this was
  implemented by extending FilterOutputStream class

16
java.io Package

• File RandomAccessFile Class
• File Class
• Provide the abstraction to deal with the file
  name and path name dependent on the host platform
  as the file name and path name independent on the
  machine
• RandomAccessFile Class
• Provide the random access file system to support
  the more various mechanism than FileStream does