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Introduction
Java is Simple high Level ,Platform independent , Architecture Neutral, Secure, Robust ,Multithreaded, Distributed, and Object Oriented programming language.
Java Characteristics /Feature/Buzzwords
• SimpleJava is easy to learn because most of the complex or confusing feature of c and C++ like pointers , operator overloading etc are not provided in java.
• Secure
Java programs run within the JVM which protects from unauthorized or illegal access to system resources.
• Platform independent/pointer
Java program can be executed on any kind of machine containing any cpu or any operating system.
• Architecture neutral
Since java application can run on any kind of CPU so it is architecture – neutral.
• Robust
Java is robust because of following..
• Strong memory management
• No pointer
• Exception handling
• Type checking mechanism
• Platform independent
Multithreaded
Java supports multithreaded programming which allows us to write programs that do many things simultaneously
• Distributed
Using RMI and EJB we can create distributed application in java
• Object oriented
Java follows object oriented programming model that helps to break the complex code into easy to understand objects
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• Language
It is the medium of communication .
• program
It is a set of instruction for a device to perform to some specific task.
• Programming Language
It contain set of grammatical rules or syntax to write a program for instructing machine to perform specific tasks.
Types of Programming Language
1. Low Level Programming 2. Middle Level Programming 3. High Level Programming
Low Level Programming Language
Binary digits (0,1) will be used to write the instruction in Low Level Language
Instruction write in binary language or native language will be understand by the machine directly . No transfer program is required.
PROBLAM
• It is very complex to write ,modify and debug the instruction written in Binary Language .
• Binary code or Native code is platform dependent.
Middle Level Programming
Assembly codes like ADD ,SUB,MUL,DIV,MOV etc .Will be used to write the instruction in Middle Level Language .
Instruction written in assembly language will not be understand by the machine directly .
Assembler is a program that should be used to convert Assembly Language To Machine Language.
PROBLAM
• The code written in Assembly Language will be processor dependent.
High Level Programming
Human understand codes like English words will be used to write the instruction in High Level Language .
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Computer or interpreter is a program that should be used to converter High Level Language to Machine Language.
Advantage
it is easy to write ,modify and the instruction written using High Level Language.
Hello.c
WINDOWS MAC OS LINUX
C Language Program Development and Exception Model
Working on Window Platform
C Source Code
C Compiler
Machine Code Or Native Code
Will be executed Successfully Will not be executed Successfully Will not be executed Successfully
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1.
What is Source Code
java Language Program Development and Exception Model
Working on Window Platform
java Source Code
Java Compiler
Byte Code
JVM JVM JVM
Native Code Native Code Native Code
Will be executed Successfully Will be executed Successfully Will be executed Successfully
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Human understandable code written using High Level Programming language is called as Source code.
2.
What is native code or Binary code or Machine code
Machine understandable code written using Low Level programming Language is called as Native code.
3.
What is byte code?
JVM understandable code generated by java compiler is called as Byte code. Byte code is also called as Magic value .
4.
Why C and C++ is platform Depedent?
When you compile c or C++ program on one operation System then compiler generates that operating system understand native code. This native code generated on one os will not run on other os diretly.
5.
Why java is platform independent?
When you compile java program on one Operating system then java compiler generates Byte code. You can run that Byte code on any os which has the JVM.
JVM is understanding the Byte code and generating native code for the corresponding os.
Because of Byte code and JVM , java is platform independent you can use – write once Run Anywhere(WORE).
6.
I have written one program in c or c++ and onather program
in java . Which program will be executed fastly and why?
C or C++ program execution is faster than java program.
Because compiled code of c or c++ program contains binary code and that binary code will be executed directly whereas compiled code of java program contain byte code and that byte code will be converted to native code first and then native code will be executed.
7.
What is java compiler?
Java compiler is a program developed in C or C++ programming language with the name “javac” . it is responsible for the following tasks.
1->It will check syntactical or grammatical errors of the programs . 2->It converts source code to byte code.
8.
What is java interpreter?
Java interpreter is a program developed in C or C++ programming language with the name “java”. It is responsible for the following tasks.
1 It will convert byte code to native code line by line. 2 It will execute that native code.
NOTE Because of converting and executing line by line, java program execution was slower in initial versions of java.
9.
What is jit compiler?
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JIT compiler compiles or translates or converts the necessary part of the byte code into machine code instead of converting line by line . Because of this performance of java program has improved.
10.
What is JDK( java Development Kit)/SDK(software
Development Kit)?
It is a set of various programs which are required for developing and executed the java programs. It is a platform dependent. Various JDKs are provided for various Operating system.
Following are various utility programs provided under JDK.
1) Java Development Tools
• Javac • Java • Javap • Jar • Etc • Source File • JRE • Etc •
What is JRE ?
JRE stands for java runtime Environment . It is an implementation of JVM . It contain class Libraries, interpreter, JIT Compiler etc. Only JRE enough to run the java program.
11.
What is JVM?
JVM stands for java Virtual Machine . It is a specification provided by SUN Microsystem whose implementation provides an environmeint to run our java applications. JVM because aninstance of JRE at run time.
Sun’s implementations of the java Virtual Machine(JVM) is itself called as JRE . Sun’s JRE is available as a part of JDK and also as a separate application.
Many vendors has implemented JVM. Some of them are SUN JRE , IBM JRE ,Oracle JRE etc.
JDK
Hello.java
Development Tools
Java Runtime Environment/java Virtual Machine
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Method Heap Stack PC Other
Area Memory Memory Register Components
Execution JIT GC Engine Compiler 0 1 0 1 0 1 0 0 1 0 1 0 0 1
Operation System/Platform
Hardware
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History
• Java was designed by sun Microsystems in the early 1990s to solve the problem of connection many household machines together.
• Initial version of java is called as OAK.
• Later java become popular for developing internet applications .
• Java is developed by James Gosling and team.
• James Gosling is considered as FATHER OF JAVA.
• It was publicly released on 1995.
• Now sun Microsystems is the part of Oracle Crop.
Editions
• Java Standards Edition(JSE)
Used to develop standalone applications using applet and swing.
• Java Enterprise Edition(JEE)
Used to develop enterprise application using Servlets,jsp,jdbc etc.
• Java Micro Edition(JME)
Used to develop applications for micro devices like Mobiles , Setup Box etc.
Java Standard Edition Versions
Java Version
Code Name
Released Year
JDK Alpha and Beta 1995
JDK 1.0 Oak 1996 JDK 1.1 1997 J2SE 1.2 Playground 1998 J2SE 1.3 Kestrel 2000 J2SE 1.4 Merlin 2002 Enterprise Edition(EE) Standerd Edition(SE) Micro Edition(ME)
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BY-A.K.JAISWAL J2SE 5.0 Tiger 2004 J2SE 6 Mustang 2006 JAVA SE 7 Dolphin 2011 JAVA SE 8 18 march 2014Java Enterprise Edition Version
EE version
Released Year
Technologies Added
Java(java Professional)
1998
JDBC 2.0JNDI 1.2 Servlets 2.2 Jsp1.1 EJB 1.1
Java Mail API1.1
J2EE1.3
2001
Servlets 2.3JSP1.2 EJB2.0
Java Mail API 1.2
J2EE1.4
2003
Servlets 2.4JSP 2.0 EJB 2.1
Java Mail API1.3
JEE 5
2006
Servlets 2.5JSP 2.1 JSF 1.2 EJB3.0 JPA1.0
Java Mail API1.4
JEE 6
2009
JDBC 4.0 Servlets 3.0 JSP 2.2 JSF 2.0 EJB 3.1 JPA2.0JEE 7
2013
JDBC 4.1 Servlets 3.1 JSP 2.3 JSF 2.2 EJB 3.2 JPA2.1J
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Installation step
• Run the installer file JDK -7u25-windows-i586.exe
• Click on NEXT button
• Clock on Change button.
• Change the destination location to E\jdk\1.7.0\
• Click on OK button.
• Click on NEXT button .
• After some time installer will prompt to select destination location for JRE.
• Use the defaults as it is and click on NEXT button then following screen will appear.
• After installation completed successfully.
• Click on close button.
Directory Structure
• After installing JDK you will get the following directory structure.
JDK Directory
JRE Derectory
E:
lib
C:
Program Files
Jdk 1.7.0
bin
jre
Srz.zip
javaJre7
Javac ,, jar.exe Java.exe ,,etc Javap Private Jre Public jreJ
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Step to write , compile , and Run Program Step to write java Program
• Select the required Workspace
• Assume we have select workspace as D:\ Mukesh \Ankush
• Use Notepad or some other text editor to create the source file.
Steps
• Click to start ->Run.
• Type notepad and click OK.
• Write a java program.
• Sava the file with the name of Hello.java in the directory D:\ Mukesh\ Ankush.
Step to compile the program
1.
Open Command Prompt as Follows
• Click on Start -> Run
• Type cmd • Click on OK JDK Directory Workspace E: Jdk 1.7.0 bin Java.exe,java.exe Java.exe,javap.exe Jar.exe,,etc D: Mukesh Ankush Hello.java
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2. Change working Directory to Workspace Directory (D:\Mukesh\Ankush)
3. Set the Path for bin directory of JDK.
D:\Mukesh\Ankush>set path =%path%;E:\JDK 1.7.0\bin;
4. Use javac compiler to compile the source code. Javac <sourceFileName With .java Ext>
Compiler will generate Hello.class file in the location D:\Mukesh\Ankush
Step to Run java Program
• Use java interpreter to execute/run the java classJava <classFileNameWithout.class Ext>
If you set the path at command line then that path will be accessed as long as that command prompt running .Even that path will not be accessed with other prompt is running at a time. So it is temporary.
You can set the PATH permanently in System Environment Variables as follows.
• Right click on My Computer and Select Properties.
• Select Advanced Tab.
• Click on Environment Variables Button.
• Click on new Button in the User Variable
• Provide the required info.
Variable the required info. PATH
Variable value E:\jdk1.7.0\bin
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COMMENTS
•
Single Line Comments (//)
// the whole line will be ignored by the compiler.
•
Documents Comments
/** will be used to
*define documentation
*of any variable, method
*in java Source File.
*/
•
Multiple Line Comments(/* */)
/* you can define as
Many lines as
You want to
Ignore from compilation.
*/
What is the difference between c++ and java?
java
C++
Java doesn’t support pointer
C++ support pointer
Java class not support multiple
inheritance with classes.
C++ supports multiple
inheritance with classes.
Java doesn’t support Global
Variable (variables declared
outside the class)
C++ supports Global Variables.
Java doesn’t support header
files.
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Const and goto keywords can’t
used in java .
Const and goto keywords can be
used in c++.
Java doesn’t supports destructor C++ support Destructor
Java doesn’t support virtual
function
C++ support virtual function.
Java doesn’t support operator
overloading .
C++ support operator
Overloading.
Java doesn’t support scope
Resolution Operator.
C++ support scope resolution
operator.
Java has a garbage collector to
clean the memory automatically.
No automatic memory cleaning
process in c++.
Java has built- in API for
multithreading and network
Programming
C++ doesn’t have Built- in API for
multithreading and network
Programming
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BY-A.K.JAISWALJava
Language Ref
Guide
Part 1
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Java Language Fundamental
•
Character Sets
•
Keywords/Reserved words
•
Identifier /User Defined Words
•
Data types
•
Variable
•
Constants
•
Literals
•
Operators
•
Control Statements
•
Arrays
1.
Character sets
Alphabets A-Z/a-z. Digits 0-9Special Characters +-*&! @#$%^ etc
White Space character newline (\n), carriage return (\r) etc
2.
Keywords/Reserved words
•
Keywords are simpleE
nglish words which are having predefined meaning in java programming Language.•
Meaning of these keywords can’t be modified.•
Keywords are also called as Reserved Words.•
All the keywords are defined in Lower Case.•
We can’t use keywords as names for variables, methods, classes, or as any other identifiers.J
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•
There are 49 keywords defined up to java 2.•
enum is the new
keyword added from java 5 so there are 50 keywords from java 5.•
const & goto are the keywords but no implementation available. You can’t use these keywords in java program.List of Keywords
Data types(8)
boolean ,byte ,chat ,short, int
,float, double
Class & object(9)
class , interface , enum,
extends, implements , this ,
supper, new.
Access Modifier(3)
Private, protected ,public
Modifier(9)
final , native, abstract,
synchronized ,transient,
volatile ,static ,const*
Package(2)
package, import
Control Statements(12)
if ,else ,switch, case, defaults
,do ,while, break, for,
continue, return
Exception Handling(6)
try , catch, finally, throw,
throws
Other data Type(1)
void
3.
Identifier /user Defined Words
• Identifiers are the names those will be used to identify the programming elements like classes, methods, variables, etc uniquely.
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•
Rules to follow when you define a identifiers
Identifiers can
contain Alphabets, Digits, and two special symbol i.e Doller ($), Underscore (_).First character of an identifier must be an Alphaber or Doller ($)
or Underscore (_).
Keywords or Reserved words can’t be used as Identifier.
Valid Identifiers
Invalid Identifiers
Hello 1stClass
Int true
getClassName student number
Total_FFE int
4.
Data types
Data type represents
•
Type of data you want to use
•
Amount of memory allocation required for your data.
There are two types of data types.
•
Primitive data types
•
User defined data types.
Primitive data types
• There are 8 primitive types available in java.
• 8 keywords are defined to represent 8 primitive data types.
Following are primitive data types.
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User Defined Data type
There are four types of user Defined Data types.
•Class type
•Interface type
•Enum type(from java 5)
•Annotation type(from java 5)
Primitive Types Floating Point Types Integral Types Numeric Types
Boolean Types boolean
byte short float double char long int
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Type
Size
Default
value
Min value
Max value
Byte Bits
boolean N/D N/D false True or false
Byte 1 8 0 -27(128) 27-1(127) Char 2 16 ASCII-0 Unicode-\u0000 0 216-1 (65535) short 2 16 0 -215 (-32,768) 215-1 (32,767) Int 4 32 0 -231 (-2147483648) 231-1 (2147483647) Long 8 64 0 -263 263-1
Float 4 32 0.0 1.4E-45 3.40E38 Double 8 64 0.0 4.9E-324 1.79E308 Any
reference type
8 64 Null Reference of The
corresponding Type object
5.
Variable
• Variable is the container which holds user data.
• Memory will be allocated for the variable while executing the program.
• Value of the variable can be changed any number of times during the program execution.
Syntax
<Data type> <varName>;
<Data type> <varName> =<value>;
EX
Int a; String str; a str
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Int a=99; String str =”SRI”; a str
4 bytes 8 bytes
32597
Types of Varialves
There are two types of variable based on data type used to declare the variable.
• Primitive Variables
• Reference Variables
Primtive Variables
•
Variable declared with primitive data type are called as primitive variable.EX
Int a; Int b; Double d1; Double d2=9.9;Reference Variables
• Variable declared with user defined data types are called ass reference variables.
EX
String str1; String str2=”Ankush” ;99
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Primitive Variable
Reference Variable
Variable declared with primitive data types are called as primitive variable
Variable declared with reference data types are called as reference variables.
Memory allocation for primitive variables depends on the primitive data types
Always 8 byte of memory will be allocated for reference variables.
Default value for primitive variables depends on primitive data types
Always null will assigned as default value for reference variables.
Primitive variables hold valid literals or value in the allocated memory.
Reference variables hold either null or address of an object in the allocated memory.
Types of variables
There are three types of variables based on the scope of the variables.
• Instance Variables.
• Static Variables.
• Local Variables.
Instance Variables
• Variables declared in the class without using static keywords are called as instance Variables.
Static Variables
• Variables declared in the class using static keyword are called as Static Varaibles
Local Variables
• Variables declared in the member of the class like method etc are called as Local variables.
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Class Hello {
Int a; instance variable
Static int b; static variable
void show(){
Int c; local variable
}
}
There a
re various syntax for declaring variables
•
Declaring a single variable in one variable declaration statement.Syntax
[modifiers]<data type> <varName>
;
EX byte b
;
int a;
double d;
char ch;
String str;
Hello h;
EtcJ
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Initializing a single variable
syntax
;
<varName> = <value/expression>;
EX
b=24;
ab=98765;
d=1234.34;
ch=’A’;
str=”Ankush”;
h=new Hello();
Declaring multiple variables of single type in one variable declaration statement.
Syntax [modifiers]<data type><var1>,<var2>,<var3>,…..
;
EX
byte b1,b2,b3,b4;
int a,b,c;
char ch1,cj2,ch3;
String str1.str2,str3;
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BY-A.K.JAISWALSyntax
<var1>=<var2>=<var3>=<value/expression>; EX a=b=c=9898;
str1=str1=str3=”Ankush” ;Declaring and initializing multiple variable of single type in one
variable declaration statement.
Syntax
[modifiers] <data type><var1>=<val1>,<var2>=<val2>,<var3>=<val3>…….
;
EX
Int a=120, b=54,c=98;
String str1=”Ankush”,str2=”Mukesh” ;
boolean b1=true,boolean b2=false;
6.
Constant
•
Constant is a special variable whose value can’t be modified during the program execution.•
Constant is also called as final variable.Syntax
[modifier]final <data Type> <varName> = <value>
;
EX
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Final String str=”Ankush” ; Final double d1=9999.99;
• A Variable that is declared as final and not initialized is called as blank final variable.
Syntax
[modifier] final <data type> <varName>
;
<varName>=<value> ;
EX
final int a
;
a=98;
• If the variable is declared as final and initialized in the same statement then in the class final compiler will replace that variable with actual value.
Default value of char is either ASCII-0 or UNICODE\u0000. Default value of char is not space.
JVM will not provide default value for Local Variable. Local variable must be initialized before using.
The local variable declared but not initialized and not used then that variable declaration statement will be removed by compiler while translation to byte code.
JVM will provide default value for static Variable
Static variable can be accessed from Static method(main method) JVM will provide default value for instance Variable
Instance variable cannot be accessed directly from Static method .
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You can’t declare multiple variables of different data types in single variable declaration statement
You can declare multiple variables of same data types in a single statement You can assign same value of multiple variables in a single statement
You can declare and initialize multiple variables of same data type in a single statement
We can’t declare two
variable with same name in same scope
Value of the variable can be changed any number of times during program
execution
Value of the final variable can not be changed We can’t use const keyword to declare constant
String str1=”Ankush”,str2=”Mukesh” ;
• Declares variable str1.
• Assigns the value Ankush to variable str1.
• Declares variable str2
• Assign the value Mukesh to variable str2
Int a,b
;
Int c=a=b=99;
•
Declares a new variable c
•
Assigns value 99 to variable b
•
Assign value of variable b to variable a
•
Assigns value of variable a to newly declared variable c
int a=a=99
;
•
declares variable a•
assign value 99 to variable aJ
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Int a=b,b=99
;//invalid
•
Declares variable a•
Trying to assign value of variable b to variable a7 .Literals
• Literals are the actual values
• Literals will be assigned to variables or constant
• Literals are also used to perform any operation
• Constant values in program are called as literals
Data type Variable Name Literals
Int a= 123;
Data type Variable Name Literals
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• Boolean Literals • Character Literals • String Literals • Integral Literals • Floating Literals • null LiteralsBoolean Literals
• boolean Literals can be assigned to a boolean type variables
• there are two boolean literals true false
Character Literals
Numeric
Literals
Non Numeric booleanString
Unsigned
Signed
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• Character Literals is a single character enclosed within a single quotation mark.
• Character Literals can be assigned to char type variable
Escape sequence
ESCAPE SEQUENCE
is a special notion is used to represent some specialcharacters which can’t be represented as it is.
Escape Sequence
Description
\t
Tab space\b
Back space
\n
New line
\r
Carriage return
\f
Formfeed
\’
Single quote character
\”
Double quote character
\\
Backslash character
ASCII Character sets
ASCII stands
for American Standard Code for information Interchange. Every character enclosed in single quotation marks will have an integer equivalent value called as ASCII value. ASCII value Range is 0-255 ASCII value can be assigned to char type variable.Unicode character
UNICODE stands for UNIversal Code Every character will have UBICODE value.UNICODE Notation
Syntax
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UNICODE Range
\u0000 (0) to \uFFFF(65535)
Octal value as char type
Octal Notation
Syntax
\DDD -D will be octal digits
Start with \ following by three octal digits Octal must be enclosed in single quotes
Octal Range
Range in Decimal 0 - 255 UNICODE 30 means \u0030 and so on Range in octal \0 - \377
Char
ASCII
OCTAL
UNIC
Char
ASCII
OCTAL
UNIC
0
1
2
3
4
5
6
7
8
9
:
;
48
49
50
51
52
53
54
55
56
57
58
59
060
061
062
063
064
065
066
067
070
071
072
073
30
31
32
33
34
35
36
37
38
39
3a
3b
<
=
>
?
@
A
B
C
D
E
F
G
60
61
62
63
64
65
66
67
68
69
70
71
074
075
076
077
100
101
102
103
104
105
106
107
3c
3d
3e
3f
40
41
42
43
44
45
46
47
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I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
a
b
c
d
e
f
g
h
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
97
98
99
100
101
102
103
104
110
111
112
113
114
115
116
117
120
121
122
123
124
125
126
127
130
131
132
141
142
143
144
145
146
147
150
48
49
4a
4b
4c
4d
4e
4f
50
51
52
53
54
55
56
57
58
59
5a
61
62
63
64
65
66
67
68
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
x
y
z
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
151
152
153
154
155
156
157
160
161
162
163
164
165
166
167
170
171
172
69
6a
6b
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String Literals
•
String literals is a collection of zero or more characters enclosed between double quotation marks.•
String Literals can be assigned to reference variable of type String•
String Literals will be represented as arrays In memory.Integer Literals
Integer Literals can be assigned to one of the integral data type –byte, short , int, long
Integer Literal size is depending on integral data type you are using Default type of integer Literal is int
There are four types of integer Literals
• Decimal literals
• Octal Literals
• Hexadecimal Literals
• Binary Literals(from java 7)
Decimal Literals
•
Decimal Literals is a valid number from decimal number system•
The base or radix of decimal number system is 10 i.e only 10 digits ranging from 0 to 9 are allowed to from the decimal Literals•
Decimal Literals must not start with 0J
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98875437
•
Octal Literals
• Octal Literal is a valid number from octal number system
• The base or radix of octal number system is 8 digits ranging from 0 to 7 are allowed to from the octal literals
• Octal Literals must start with 0(zero)
•
hexadecimal Literals
•
Hexadecimal Literal is a valid number from hexadecimal number system
•
The base or radix of hexadecimal number system is 16 i.e only 16 digits
ranging from 0 to 9
•
And A/a to F/f are allowed to from the hexadecimal Literals
•
Hexadecimal Literals must start with 0X/0x.
•
Binary Literals (from java 7)
• Binary Literals is a valid number from binary number system
• The base or radix of binary number system is 2 i.e only 2 digits 0 and 1 are allowed to form the binary Literals
• Binary literals must start with 0B/0b 0b1010
0B111010101010
•
Floating point Literals
• Floating point Literal can be assigned to one of the floating point data type –float, double .
• Floating point Literal size is depending on floating point data type you are using
• Default type of floating point Literals is double
• You can use D/d as a suffix for the double value optionally.
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• Floating point Literals can be represented using following notations Standard floating point notation
Exponent / scientific notation Hexadecimal Notation (from java 5)
Decimal point 1/10 1/100 Tens Units 1/1000
12.876
10x Bigger 10x smaller
•
Standard Floating point Notation
•
It consists of a whole number followed by a decimal point and fractional part 1234.762345.7609
•
Scientific / Exponent Notation
• The exponent is indicated by an E or e following number, which can be positive or negative
123.4567e2 ->123.4567*102 123.4567E2 ->123.4567*102
12345.67e-2 ->12345.67
*102•
Hexadecimal floating literals (from java 5)
• It allows literals of the float and double types to be written primarily in base 16 rather than base 10.
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BY-A.K.JAISWALDouble x =0xap0;
a->10 //10*20=10.0Double y =0xfp2D;
f->15 //15*22=60.0float z =0xf.ap1F;
f->15 a->10 //(15*160+10/161)*21 //(15*1+.625)*2 //15.625*2)=31.25fDouble d1=0x1f.a5p1;
//(1*161+15*160+10/161+5/162)*21 //(16+15+10/16+15/256)*21 //(16+15+.625+.01953125)*2 //(31.64453125)*2 //63.2890625null Literals
•
null is a value•
it is default value for any reference variable•
if the value of reference variable is null then it indicates that address/reference is not available in the variableUNDERSCORE in numeric Literals(from java 7)
to represent the unit of the values you can use comma (,) symbol in number representationEX
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you can do the same task with UNDERSCORE (_) from java 7 towards
EX
2_45_12_452
1)
A boolean type variable can hold either true or false2)
A boolean type variable can’t hold numeric value0 not equals to false
Non zero values not equals to true
3)
Boolean literals – true and false are reserved words and must be in lower case true not same as True TRUE, True, TrUe etc false not same as FALSE ,False, FaLse etc4)
a char type variable can hold following
Single character enclosed in single quotation marks
Escape sequence
ASCII value
UNICODE character
5)
SPACE is valid character so it can be placed in single quotation marks
6)
TAB is valid character so it can be placed in single quotation marks
7) Back space character (\) is used to form escape sequence so only backspace
character can’t be placed in single quotation marks
8) Single quote is used to form character literal so only single quote can’t be
placed in single quotation marks
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9) There are some character like backslash, single quote which can’t be placed
in single quotes as it is. those special characters have to be represented as
escape sequence
10)
Every character enclosed in single quotation marks will have an integer
equivalent value called as ASCII value
11)
Char type variable can hold integer value ranging form 0-65535 only
12)
Char type variable can hold UNICODE value ranging from \u0000-\uFFFF
only
13)
Char type variable can hold OCTAL value ranging from \0-\377 only
14)
When you print he char type variable which holds integer, UNICOE or
octal value then it displays corresponding character representation
15)
If integer , UNICODE value don’t have character representation then it
displays? Which indicates no character defined for that value.
16)
When you assign character literals to int type variable then internally
ASCII value of that character will be assigned.
17)
Source code can also be written in UNICODE representation
•
Int a=\u0037; int a=7; //valid
•
Int a=’\u0039’; int a=’7’; //valid
•
Int a=\u0037\u0037; int a=79; //valid
•
Int a=’\u0037\u0037’ int a=’79’; //invalid
18)
Empty string Literal is allowed whereas empty character literal is not
allowed
19)
If reference variable of String type contains null value then it is called as
NULL String
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20)
You can’t refer any member with NULL String . if you do so it results in
NullPointerException
21)
If reference variable of String type contains zero character in double
quotations marks then it is called as EMPTY String .
22)
When java compiler encounters any UNICODE/Octal value in String
literals then that UNICODE/Octal value will be replaced with actual
character
23)
You can use escape sequence to represent UNICODE/Octal value as it is
in String literals
24)
There are four types of integer literals
•
Decimal Literals
•
Octal V Literals
•
Hexadecimal Literals
•
Binary Literals(from java 7)
25)
Default type if integer Literal is int
26)
Integer value ranging from -2147483648 to 2147483647 can be
represented directly
27)
If you want to represent the integer value out of int range then you need
to use L/l ssuffix
28)
Decimal literals must not start with 0
29)
Octal Literal must start with 0(zero)
30)
Hexadecimal literal must start with 0X/0x
31)
Binary literal must start with 0B/0b
32)
When java compiler encounters octal , Binary or Hexadecimal Literals
then that will be replaced with decimal equivalent value
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34)
You can use D/d as a suffix for the double value optionally
35)
You must use F/f as a suffix for float value
36)
When integer value starts with 0 then it will be considered as octal
literals
37)
When floating point value starts with 0 then it will be considered as
floating point literals only , not as octal literals
38)
When integer value starts with 0X/0x then it will be considered as
Hexadecimal literals
39)
When floating point value starts with 0X/0x then it must use p in
fractional part
40)
When integer value starts with 0B/0b then it will be considered as binary
literals
41)
Floating point cannot be represented as Binary Literal
42)
You can use UNDERSCORE in numeric Literals to represent unit of values
from java 7
43)
When UNDERSCORE is used before first digit then it will be considered as
a variable
44)
You can’t use UNDERSCORE after the last digit
45)
In the case of octal literal UNDERSCORE can be used just after 0
46)
In the case of binary literal UNDERSCORE can’t be used just after the
0B/0b
47)
In the case Hexadecimal literal UNDERSCORE can’t used just after 0X/0x
48)
You can use more than one UNDERSCORE side by side between two
digits
49)
You can use UNDERSCORE with floating point literal but not allowed just
before or after the decimal point
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Part -2
Operator
• Operator at used to perform operations by using operands
• There are three types of operator depending on the number of operands required Unary operator –only one operand is required.
Binary operator-two operands are required Ternary operator- three operands are required
Following are the types of operator depending on the operation
• Arithmetic operators
Unary arithmetic operator Binary arithmetic opetator
• String concatenation operator
• Assignment operator
Simple assignment operator Compound assignment operator
• Increment & decrement operator
• Relational operators
• Logical operator
• New operator
• New operator
• Instance operator
• Conditional or Ternary operator
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Arithmetic operator
• Arithmetic operator are used to form arithmetic expression to perform the arithmetic operations.
• Operands used in arithmetic expression can be of numeric type or char type
• Result of arithmetic type operation is always int or wider than int type.
Operand1 operator operand2
10 + 20
Unary Arithmetic operators
Operator
Name
description
+
plusReturn same value
with same sign
-
Minus
Return same value with
opposite sign
Binary Arithmetic operators
Operator
Description
+
Addition(sum)
-
Subtraction(difference)
*
Multiplication(product)
/
Division(quotient)
%
Modulus(remainder)
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•
When the operands are int or lower than int type then result will be
int type only.
•
When any one operand or both the operands are wider than type
then result will be wider type.
1
stoperand type
2
ndoperand
Result type
byte
byte
int
char
char
int
short
byte
int
int
int
int
int
long
Long
byte
double
double
float
int
float
float
long
float
char
double
double
int
double
double
char
int
int
short
char
int
short
float
float
etc
String Concatenation Operator(+)
•
It is a binary operator•
+ operator can be used for two purposesArithmetic addition
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•
Arithmetic Addition
When both the operands of + operator are numeric type
then it will perform arithmetic addition
EX
90 + 9 = 99;
Result of arithmetic addition is numeric type
• String concatenation
When any one or both the operands of + operator are String type it will perform String concatenation.
EX
“90” + 9 = 909 9 + “90” = 909 “90” + “9” =909
Result of String concatenation is String type.
Simple Assignment Operator(=)
• it is binary operator
• it is used to assign the value to a variable <operand1> = <operand2>
Operand1 must be a variable
Operand2 can be a variable, value or expression.
• The variable , value or value of an expression must be assignment compatible type.
byte
char short
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Type Casting
• <Operand1> = <operand2>
• Here operand2 is the source , operand1 is destination and we are assigning source to destination.
• Usually source type must be same as destination type
• When source type is not same as destination type then source type must be converted to destination type . This process of converting one type to another is called as Type casting.
• Type casting can be done in two ways. Implicit casting
Explicit casting Implicit casting
When type casting is happening automatically by the JVM then it is called as Implicit Casting.
Explicit casting
When type casting is done by the programmer explicitly then it is called as Explicit Casting.
SYNTAX
<dest Type><dest var> = (<dest type>)<source value> EX
Int a=10; byte b= (byte)a;
There are two type of conversions
Widening Narrowing•
Widening
Widening is the process of converting lower type to higher type . this is safe conversionJ
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EX
byte b=10;
int a= b; //valid - implicit casting int a= (int )b; //valid – Explicit casting
here you are casting byte to int . byte has a range from -128 to 127 where as int has a range from -2147483648 to 2147483647 . so any value that fits in a byte will fit in a int also . because of this there is no data loss and conversion is considered as sage.
•
Narrowing
Narrowing is the process of converting higher type to lower type
EX
Int a=300;
byte b=a; //invalid implicit casting byte b=(byte)a; //valid explicit casting
here you are casting int to byte . Range of byte is much smaller than range of int . what happens when you convert an int value 300 to a byte.
This result 44 i.e data is lost so conversion is considered as unsafe. Int a=300; ->int means 32 bits memory required
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 1 0 1 1 0 0
byte b1=(byte)a; ->byte means 8 byte memory required 0 0 1 0 1 1 0 0
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BY-A.K.JAISWAL 0*27+0*26+1*24+0*23+1*22+0*21+0*20 0+0+32+0+8+4+0+0=44 double val 300.9898; byte b2=(byte)val; =44.Compound Assignment Operators
• Compound assignment operator provide a shorter syntax for performing
operations and assigning the result of an arithmetic operator or bitwise operator
EX
int a=90;
a+ = 9; => a = a+9;
• In the above expression two takes are happing
Performs the Arithmetic operation on the operads. Assigns the result to the first operands
• There are 11 compound assignment operators as shown below
Operator
description
+= Add right operand to left operand and
assign the result to left operand.
-= Subtract right operand from left operand and assign the result to left operand
*= multiple right operand to left operand and assign the result to left operand
/= divide right operand to left operand and assign the result to left operand
%= Calculate modulus using two operands
and assign the result to left operand &= assigns the result of the logical AND |= assigns the result of the logical OR
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^= assigns the result of the logical XOR <<= assigns the result of the signed left shift
operator
>>= assigns the result of the signed right shift operator
>>>= assigns the result of the unsigned right shift operator
Increment (++) / Decrement (--) Operators
• Increment operator will be used to increase the value of the variable by 1
• Decrement operator will be used t decrease the value of the variable by 1
Relational operators
• These are binary operators
• Relation operators forms the relational expressions
• Result of relation expression is Boolean type i.e true or false
Comparison Operators
description
> Greater than
< Less than
>= Greater than or equal to
<= Less than or equal to
• Operands of comparison operators must be number or char type
Equality operators
Description
== Equal to
!= Not equal to
• Operands of equality operators can be numeric , char, boolean or reference type.
Logical operators
• Logical operators are used to form logical expressions
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• Result of logical expression will be boolean type i.e true or false
Logical operator Description
! Logical NOT
&& Logical AND
|| Logical OR
Logical NOT
• It is unary operator
• It is used to inverse the result
OPERAND Result
true false
false true
Logical OR and Logical AND
• These are binary operators
• Logical OR and Logical AND operators used to combine two relational expressions to from logical expressions
EX
(a>b) && (a>c) (a<b) || (a<c)
Logical AND (&&)
•
Result of logical AND is true if both the operands are true otherwise falseOP1
OP2
Result (op1 && Op2)
true
true
true
true
false
false
false
true
false
false
false
false
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•
Result of Logical OR is false if both the operands are falseotherwise true.OP1
OP2
Result (op1 || Op2)
true
true
true
true
false
true
false
true
true
false
false
false
New operator
• new operator is used to create the new object for class
• it returns of the address of the address of newly created object
Instanceof Operator
• it is used to check whether the given object belongs to specified class or not
• Result of instanceof operator is Boolean value
• It is also called as TYPE COMPARISION OPERATOR
Conditional operator
• It is ternary operator
<Operand1> ? <Operand > : <Operand3>
• Operand1 must be of boolean type
• If operand1 is true then Operand2 will be returned otherwise Opetand3 will be returned
Bitwise Operators
• These operators will be used to perform the operation on individual bits of the value.
Bitwise Operators
Description
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& Bitwise AND
| Bitwise OR
^ Exclusive OR (XOR)
<< Left Shift
>> Right shift
>>> Unsigned Right Shift
• Operands for the following Bitwise Operators can be of boolean type or integer type .
Bitwise AND Bitwise OR
Exclusive OR (XOR)
• Operands for the following Bitwise Operands will be of Integer type only Bitwise NOT
Left Shift Right shift
Unsigned Right Shift
1’s Complement
• 1’s complement if a binary number is formed by changing 1’s to 0’s and 0’s to 1’s
2’s Complement
•
2’s complement of a binary number is formed by adding1 to the least significant bit of 1’s complement0 0 1 0 1 1 0 1
1 1 0 1 0 0 1 0
Actual Bits
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0
1
0
1
1
0
1
1
1
0
1
0
0
1
0
+
1
1
1
0
1
0
0
1
1
Bitwise NOT Operator
•
It inverts the bit pattern and returns decimal equivalent value.•
This is equivalent to 1’s complement Int x=15; Sign bit64 32 16 8
4
2
1
0 0
0 0
1
1
1
1
1
1
1 1
0
0
0
0
Int x =45
; Sign bit64 32 16 8
4
2
1
0 0
1 0
1
1
0
1
1
1
0 1
0
0
1
0
Shortcut method
~OPERAND = -(OPERAND + 1) Actual Bits 1’s ComplementAdding 1 with value
2’s Complement
Binary of 15
1’s Complement (~x)=-16
Binary of 45
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~198 => -(198 + 1)=> -199 ~-198 => -(-198 +1) => -(-197) => 197Bitwise operator
• Bitwise AND operator is similar to Logical AND operator with following differences
Logical AND
Bitwise AND
Operands are Boolean type only Operands can be Boolean as well as integra type
When first expression value is false then second expression will not be evaluated
When first expression value is false then second expression also will be evaluated Result is Boolean type When operands are Boolean type then
result is boolean type
When operands are integral type then result is integral type.
OP1
OP2
Result (Op1 & Op2)
1 1 1
1 0 0
0 1 0
0 0 0
Bitwise OR Operator
• Bitwise OR operator is similar to logical OR Operator with following defferences.
Logical OR
Bitwise OR
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type When first expression value is true then
second expression will not be evaluated
When first expression value is true then second expression also will be evaluated Result is Boolean type When operands are Boolean type then
result is boolean type
When operands are integral type then result is integral type.
OP1
OP2
Result (Op1 & Op2)
1 1 1
1 0 0
0 1 1
0 0 0
Exclusive OR Operator (XOR)
• Operands can be Boolean as well as integral type
• Both the expressions are Boolean type then result is Boolean type
• When operands are Boolean type then result is Boolean type
• When operands are integral type then result is integral type
OP1
OP2
Result (Op1 ^ Op2)
1 1 0
1 0 1
0 1 1
0 0 0
Left shift Operator (<<)
