JDK TUTORIAL

Assignment Operator In JAVA

2009-03-23T10:36:00.000-07:00

The assignment operator in java is the most frequently used operator. This operator is used to assign the value on its right to the variable on the left. The general format for the assignment operator is given below.

variable_name = expression;

where,
expression is an arthmetic expression built using constants, variables and binary operators.
variable_name is the name of the variable to which the expression should be assigned.

For Example

a = 3;
x = 1*3;
num - x+8;
num1 = (4*a)+(21-a)

Note
It is also possible to assgn single value to multiple variables as shown below.

i = j = k = 10;
which will assgn the value 10 to the variables i, j and k.

Binary Operators In JAVA

2009-03-23T10:17:00.000-07:00

As the name itself indicates, binary operators are operators that operate on two operand. The following table gives lists the different binary operator available in java.

Operator	Operation	Example
+	Addition	2+3 is 5
-	Subtraction	8-2 is 6
*	Multiplication	2*5 is 10
/	Division	8/8 is 1
%	Modulo	15%2 is 1

Example Program

class binaryoperatorexample

{

public static void main(String args[])

{

int a=10,b=5,c,d,e,f,g;

c=a+b;

d=a-b;

e=a*b;

f=a/b;

g=a%b;

System.out.println("Addition:"+c);

System.out.println("Subtraction:"+d);

System.out.println("Multiplication:"+e);

System.out.println("Division:"+f);

System.out.println("Modulo:"+g);

}

Please make sure to include all the necessary header files before compiling the program. The output of the program will be as below.

Addition: 15

Subtraction: 5

Multiplication: 50

Division: 2

Modulo: 0

What Is A Variable?

2009-03-18T13:00:00.000-07:00

A variable is a name of memory location , which can store one constant at a time. Like constants, variable can also be any one of the eight primitive data types.
Every variable is identified by a variable name. The following points should be kept in mind when deciding the variable name.

The variable name must start with an alphabet and can contain only alphabets , numbers,underscores and $ sign.
It cannot have a blank spaces.
Java keywords should not be used as variable names.
Java is a case sensitive so a variable in uppercase is diffrent from the variable in lowercase.

What Is A Constant?

2009-03-18T12:54:00.000-07:00

A constant is a any data that cannot be changed. In JAVA, constants can be of any basic eight data types.
For example,

-23 is a byte constant.
3213 is an integer constant.
13.654 is a float constant.
true is a Boolean constant.

Integer constant can also be represented in octal and hexadecimal forms. An octal number should begin with the digit 0 and can contain the digits 0 to 7. A hexadecimal must start with the character sequence 0x and can contain the digits 0 to 9 and the alphabets A,B,C,D,E and F.

Data Types In Java

2009-03-18T12:19:00.000-07:00

Data type in java can be of 8 basic type and these data types are called as primitive data types. The Following table contains the primitive data types.

Data Type	Size	Description
Boolean	1 Bit	Can be either true or false
Char	16 Bits	Can be single character enclosed with single ‘.
Byte	8 Bits	Integers between -128 to 12
Short	16 Bits	Integers between -32768 to 32767
Int	32 Bits	Integers between -2147483648 to 2147483647
Long	64 Bits	Integers between -9223372036854775808 to 9223372036854775807
Float	32 Bits	Single precision numbers in the range 3.4e-38 to 3.4e38
Double	64 Bits	Double precision number in the range from 1.7e-308 to 1.7e308

Java Developers Kit

2009-03-12T13:43:00.000-07:00

The Java Developers Kit is known as JDK, is a collection of tools and necessary documents for making java application and applets. The JDK consist of

The java compiler javac.exe to convert java programs into bytecode.

The java interpreter java.exe translates bytecode into program action to be executed by JVM.

The Java debugger jdb.exe to debug the programs.

The Java disassembler javap.exe to display certain specific interfaces.

The Java header file generator javah.exe.

The Java documentation javadoc.exe.

AppletViewer.

what is an array?

2009-03-12T13:32:00.000-07:00

An array is a group of variables of same data type. These variables are grouped together under a common name. Each individual variable is called as an array element and it is numbered as 0,1,2,3 and so on. These numbers are called the subscripts. An array element is referred to by the common name and its subscript enclosed in square brackets[].

For example, if the num is an integer array of size 5, these numbers would be referred as num[0], num[1],... num[4] where the number 0,1,2,3,4 are called the subscripts.

Important Rules In Array

The Subscripts of an array always begins with 0.

It is an integer.

It cannot be a negative number.

The subscripts should be enclosed with [].

Structured Programming Example

2009-03-02T10:18:00.001-08:00

class sample
{
/*A sample program to show how functions can be used*/
// Main Program
public static void main(String args[])
int year=1956;
//call function
if(leap_year(year))
System.out.println(year+" is a leap year");
else
System.out.println(year+" is not a leap year");
}
// Main Program Ends
//Function Begins
static boolean leap_year(int yr)
{
if(yr % 400== 0)
return true;
if(yr % 100== 0)
return false;
if(yr % 4== 0)
return true;
else
return false;
}
}

what is structured programming?

2009-03-02T10:06:00.000-08:00

In the word of Dijkstra, an eminent computer scientist "the art of programming is the art of organising complexity". He goes on to add that "we must organize the computations in such a way that our limited powers are sufficient to guarantee that the computation will establish the desired effect".

As programs becomes larger verifying them for correctness becomes very difficult. Any amount of testing would be hopeless inadequate unless the internal structure of the program is taken into account. The syntax and the other features of a language must prevent the programmers from making errors.

Languages based on this principle ensure that the flow of control is evident from the structure of the program text. The support for sub-programs and functions in high level languages simplifies the expression of large program in structured manner.