1. elementary programming
lab2 PROGRAMMING 1
elementary programming

2. BEFORE WE START Your Cell Phone Silent Please Keep Quite
Find Your Computer and Switch On
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3. content Anatomy of a Java Program. Special Symbols . Java Basic Syntax
Java Data Types
Java Identifiers
Operator In Java
To cast the value of one type to another type.
Output with Character Escape .
Input.
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4. Anatomy of a Java Program
Class name
Main method
Statements
Statement terminator
Reserved words
Comments
Methods
Modifiers
Blocks
Class Name & Main method
In order to run a class, the class must contain a method named main. The program is executed from the main method.
Every Java program must have at least one class. Each class has a name. By convention, class names start with an uppercase letter. In this example, the class name is Welcome.
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5. Statement & Statement Terminator
Anatomy of a Java Program
Statement & Statement Terminator
A statement represents an action or a sequence of actions. The statement System.out.println("Welcome to Java!") in the program is a statement to display the greeting "Welcome to Java!“.
Every statement in Java ends with a semicolon (;).
Reserved words
Reserved words or keywords are words that have a specific meaning to the compiler and cannot be used for other purposes in the program. For example, when the compiler sees the word class, it understands that the word after class is the name for the class.
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6. Anatomy of a Java Program
Comments
In Java, the comments used to describe the Java code. They are preceded by two slashes (//) in a line, or enclosed between /* and */ in one or multiple lines.
When the compiler sees //, it ignores all text after // in the same line. When it sees /*, it scans for the next */ and ignores any text between /* and */.
Modifiers & Blocks
Modifiers specify which parts of the program may see and use any particular class/method/field.
A modifier is a Java reserved word that specifies particular characteristics of a programming construct.
Java has three visibility modifiers: public, private, and protected.
A pair of braces in a program forms a block that groups components of a program.
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7. Special Symbols
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8. Java Basic Syntax
*Case Sensitivity - Java is case sensitive which means identifier
Hello and hello would have different meaning in Java.
*Class Names - should be in Upper Case.
*Method Names - should start with a Lower Case letter.
*Program File Name - should exactly match the class name.
*public static void main(String args[ ]) - java program processing
starts from the main() method which is a mandatory part of
every java program.
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9. Java Primitives Data Types
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10. Character and String String: Character :
String is used to represent more than a single character.
There are 3 ways to define string:
a) By Creating a String Object
String s=new String("abcdef"); b) By just creating object and then referring to string String a=new String(); a="abcdef"; c) By simply creating a reference variable String a="abcdef“;
Character :
Character is used to represent a single character.
Char c='A‘;
Char C=97;
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11. Java Identifiers(variable)
What is a variable?
variables are used to store values to be used later in a program.
Why ?
They are called variables because their values can be changed.
Java provides the programmer with different types of data but basic data types are most required: integer (int), real (float) ,double and character (char).
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12. Declaring a variable(identifier)
The syntax for declaring a variable is:
Datatype variable name;
An identifier is a sequence of characters that consists of letters, digits, underscores(_), and dollar signs ($).
An identifier must start with a letter, an underscore (_), or a dollar sign ($). It cannot start with a digit
An identifier cannot be a reserved word. Ex: true, false, or null.
An identifier can be of any length.
Here are some examples of variable declarations:
Int count;
float radius;
double Rate;
Constant:
the syntax for declaring a constant:
final datatype CONSTANTNAME = VALUE;
Example:
final double PI = ;
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13. Example of identifiers(variables)
Valid identifier
Invalid Identifier
Name
Error
Letter1
1Letter
start with a digite
integer
int
A key word
Mark94
Mark 94
Contain a space
maining
main
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14. Assigning Values to Your Variables
In Java, the equal sign (=) is used as the assignment operator.
The syntax for assignment statements is as follows:
1- variable = value; variable = expression;
Example:
int Width;
Width = 5;
You can combine these steps and initialize Width when you define it by writing: int Width = 5;
If the right part is an expression
int I=9;
int J=13;
int z=I+J;
Note:
In an assignment statement, the data type of the variable on the left must be compatible with the data type of the value on the right.
For example, int x = 1.0 would be illegal, because the data type of x is int.
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15. Kinds of Operator Arithmetic Op. : + - * / %
Relational Op. : > >= < <= == !=
Logical Op. : && || !
Inc/Dec Op. :
Bit Op. : & | ^ ~ << >> >>>
Operators of Java
Conditional Op. : ?:
Assign Op. : = += -= *= /= %= &= ^= |= >>= <<= >>>=
Casting Op. : (Data Type)
Array Op. : []
Method Op. : () .
instanceof Op. : instanceof
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16. Casting Operator
Widening a type can be performed automatically without explicit casting
Narrowing a type must be performed explicitly.
Example
int j=1;
double b =j; (automatically)
j=(int)b; (explicit )
Assignment Operator
Syntax:
variable or(constant) = expression; or value
In variable declare.
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17. Arithmetic Operators Result Example Meaning Name 35 34+1 Addition + 33
34-1
Subtraction -
9000
30*300
Multiplication *
0.5
1/2
Division / 2
20%3
Remainder %
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18. Shortcut Operators Operator Example Equivalent += a += 3; a = a + 3;-=
a -= 10;
a = a - 10; *=
a *= 4;
a = a * 4; /=
a /= 7;
a = a / 7; %=
a %= 10;
a = a % 10;
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19. Increment and Decrement Operators
++ increments the value of its operand by 1.
-- decrements the value of its operand by 1.
Syntax:
Pre-increment: ++variable
Post-increment: variable++
Pre-decrement: --variable
Post-decrement: variable--
OUTPUT
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20. Operations Priority 2 3 1 5 4 Operator Order of evaluation Operation
( )
left - right
parenthesis for explicit grouping
++ --
right - left
preincrement, predecrement
postincrement, postdecrement
* / %
multiplication, division, modulus
+ -
addition or String concatenation, subtraction
= += -= *= /= %=
assignment
For the following expression, in what order are the operators
evaluated in Java?
++a / (b + c) - d % e 2 3 1 5 4
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21. Output: Writing To Console
Character Escape Sequence Name
\b Backspace
\t Tab
\n Linefeed
\f Formfeed
\r Carriage Return
\\ Backslash
\' Single Quote
\" Double Quot
Output: Writing To Console
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22. Input: Reading from Console
Example:
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23. Exercise 1
Write a program that converts a Fahrenheit degree to Celsius using the formula??
In Java
Celsius = (5.0/9.0) * (Fahrenheit – 32); 1 2 3
OUTPUT
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24. Exercise 2
Write a program that converts a Celsius degree to Fahrenheit using appropriate input function to read the degree from the user.?
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25. Home Work
Write a program that computes the average of 3 students grades which are entered by the user?.
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26. Thank You !