Q) Class
Class
encapsulate the run-time state of an object or interface. Methods in this class
are
static Class forName(String name) throws
ClassNotFoundException
|
getClass()
|
getClassLoader()
|
getConstructor()
|
getField()
|
getDeclaredFields()
|
getMethods()
|
getDeclearedMethods()
|
getInterface()
|
getSuperClass()
|
Q) java.jlang.Reflect (package)
Reflection
is the ability of software to analyse it self, to obtain information about the
field, constructor, methods & modifier of class. You need this information
to build software tools that enables you to work with java beans components.
Q) InstanceOf
Instanceof means by which your program can obtain run time type information about an object.
Ex:- A a = new A();
a.instanceOf A;
Q) Java pass arguments by value are by reference?
A) By value
Q) Java lack pointers how do I implements classic pointer structures like linked list?
A) Using object reference.
Q) java. Exe
Micro soft provided sdk for java, which includes “jexegentool”. This converts class file into a “.Exec” form. Only disadvantage is user needs a M.S java V.M installed.
Q) Bin & Lib in jdk?
Bin contains all tools such as javac, appletviewer and
awt tool.
Lib contains API and all packages.
Collections
Frame Work
Q)
Collection classes
|
Collection Interfaces
|
Legacy classes
|
Legacy interface
|
Abstract collection
|
Collection
|
Dictionary
|
Enumerator
|
Abstract List
|
List
|
Hash Table
|
|
Abstract Set
|
Set
|
Stack
|
|
Array List
|
Sorted Set
|
Vector
|
|
Linked List
|
Map
|
Properties
|
|
Hash set
|
Iterator
|
||
Tree Set
|
|||
Hash Map
|
|||
Tree Map
|
|||
Abstract Sequential List
|
Collection Classes
Abstract collection à
Implements most of the collection interfaces.
Abstract List à
Extends Abstract collection & Implements List
Interface. A.L allow “random access”.
Methods>>
void add
(int index,
Object element),
boolean
add(
Object o),
boolean
addAll(
Collection c), boolean
addAll(int index,
Collection c), Object remove(int index), void clear(), Iterator
iterator().
Abstract Set à
Extends Abstract collection & Implements Set
interface.
Array
List à
Array List extends AbstractList and implements the List
interface. ArrayList is a variable length
of array of object references, ArrayList support dynamic array that grow
as needed. A.L allow rapid random access to element but slow for insertion and
deletion from the middle of the list. It will allow duplicate elements. Searching
is very faster.
A.L
internal node traversal from the start to the end of the collection is
significantly faster than Linked List traversal.
à
A.L
is a replacement for Vector.
Methods>>void
add
(int index,
Object element),
boolean
add(
Object o),
boolean
addAll(
Collection c), boolean
addAll(int index,
Collection c), Object remove(int index), void clear(), object get(int
index), int indexOf(Object element), int
latIndexOf(Object element), int size(), Object [] toArray().
Linked List à Extends AbstactSequentialList and implements List
interface. L.L provide optimal sequence access, in expensive insertion and
deletion from the middle of the list, relatively slow for random access. When
ever there is a lot of insertion & deletion we have to go for L.L. L.L is accessed via a reference to the first
node of the list. Each subsequent node is accessed via a reference to the first
node of the list. Each subsequent node is accessed via the link-reference
number stored in the previous node.
Methods>>
void addFirst(Object obj), addLast(Object obj), Object getFirst(), Object
getLast(),void add
(int index,
Object element),
boolean
add(
Object o),
boolean
addAll(
Collection c), boolean
addAll(int index,
Collection c), Object remove(int index), Object remove(Object o), void
clear(), object get(int index), int indexOf(Object element), int latIndexOf(Object
element), int size(), Object [] toArray().
Hash
Set à
Extends AbstractSet & Implements Set interface, it
creates a collection that uses HashTable for storage, H.S does not guarantee
the order of its elements, if u need storage go for TreeSet. It will not allow
duplicate elements
Methods>>boolean
add(Object o), Iterator iterator(), boolean remove(Object o), int size().
Tree
Set à
Extends Abstract Set & Implements Set interface.
Objects are stored in sorted, ascending order. Access and retrial times are
quite fast. It will not allow duplicate elements
Methods>>
boolean add(Object o),
boolean
addAll(
Collection c), Object first(), Object last(), Iterator iterator(),
boolean remove(Object o).
Hash
Map à
Extends Abstract Map and implements Map interface. H.M
does not guarantee the order of elements, so the order in which the elements
are added to a H.M is not necessary the order in which they are ready by the
iterate. H.M permits only one null values in it while H.T does not
à
HashMap
is similar to Hashtable
.
Tree
Map à
implements Map interface, a TreeMap provides an efficient
means of storing key/value pairs in sorted order and allow rapid retrieval.
Abstract
Sequential List à
Extends Abstract collection; use sequential access of its
elements.
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