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Basic Elements Of Java Language

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Variables

Storage name of particular data type having specific value. They declares under specific daa type it may be

Integer (example 0,1,2 or- 47 etc ) Boolean (example may be true or false) Double (10.2, 1.1 or -2.1 etc) String (shows text format e.g “JAVA", Pakistan etc they are strings)


Operators

Those symbols perform simple calculation. Addition + Subtraction - Multiplication * Division / && (and) e.g (1 < x) && (x < 100) || (or) e.g (lightsOn) || (isDayTime) ! (not) e.g !(isStopped)


Shortcut Assignment operators


Operator Example Equivalent

+= i+=8 i = i+8

-= f-=8.0 f = f-8.0

*= i*=8 i = i*8

/= i/=8 i = i/8

%= i%=8 i = i%8

Arithmetic Expressions


3+4x _ 10(y-5) (a+b+c) + 9 4 9+x 5 x x y

In code It well be translated like:

(3+4*x)/5 – 10*(y-5)*(a+b+c)/x + 9*(4/x + (9+x)/y)

Unicode Format

• Description Escape Sequence Unicode

• Backspace \b \u0008

• Tab \t \u0009

• Linefeed \n \u000a

• Carriage return \r \u000d



Comparison Operators

• Operator Name

• < less than

• <= less than or equal to

• > greater than

• >= greater than or equal to

• == equal to

• != not equal to

Commenting

Single Line We need forward slashes // for single line commenting. for example

// this is a single line comment

Multiple Line We use /* in first line and at the end line */ For example

/* this is multiple line comment Second line Third line And last one */


Try First Program

Import acm.graphics.*;

Import acm.program.*;

Public class FirestProgram extends GraphicsProgram {

Public void run() {

Add{ new GLabel {“My First Program”,100,75}};

}

}


END LECTURE # 3

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