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Java Review
Course Curriculum
 Module 1
» Java Basics
 Module 2
» Java Constructs
 Module 3
» OOP Concept
 Module 4
» Interfaces a...
What is Java ?
• Java
- Java is not just a programming language but it is a complete
platform for object oriented programm...
Java Virtual Machine (JVM)
• Runs the Byte Code.
• Makes Java platform independent.
• Handles Memory Management.
Byte Code
• Java bytecode is the form of instructions that
the Java Virtual Machine executes
• A Java programmer does not ...
Garbage Collection
• The programmer is not responsible for memory
management in Java.
• The memory area in JVM where objec...
Garbage Collection
Garbage Collection
Garbage Collection
Garbage Collection
How Java works ?
• Java compilers convert your code from human readable to
something called “bytecode” in the Java world.
...
How Java works ?
Basic Java Syntax
Data Types in Java
• Data types define the nature of a value
• We need different data-types to handle real-world informati...
Primitive Types and Variables
• boolean, char, byte, short, int, long, float, double etc.
• These basic (or primitive) typ...
Naming Convention of Variables
• Can start with a letter, an underscore(_), or a dollar sign ($)
• Cannot start with a num...
Statements & Blocks
• A simple statement is a command terminated by a semi-colon:
name = “Fred”;
• A block is a compound s...
Flow of Control
• Java executes one statement after the other in the
order they are written.
• Many Java statements are fl...
Java Basic Constructs
• If
• If…else
• Nested If…else
• Switch Statement
If else– Syntax
if ( <condition> )
{
// Execute these statements if <condition> is TRUE
}
If else– Syntax
if ( <condition> )
{
// Execute these statements if <condition> is TRUE
}
else
{
// Execute these statemen...
If else– Syntax
if ( <condition1> )
{
// Execute these statements if <condition1> is TRUE
} else if ( <condition2> )
{
// ...
switch– Syntax
switch (expression)
{
case cond1:
block_1;
break;
case cond2:
block_2;
break;
...
default:
block_default;
}
Operators
• Provide a way to perform different operations on
variables
• Categories of Java Operators
Assignment Operators...
Assignment and Arithmetic Operators
• Used to assign a value to a variable
• Syntax
– <variable> = <expression>
• Java pro...
Relational Operators
• Used to compare two values.
• Binary operators, and their operands are numeric
expressions.
Relatio...
Logical Operators
• Return a true or false value based on the state of
the variables
• There are six logical operators
Con...
Static versus Non-static Variables
• Static variables are shared across all the objects of a
class
– There is only one cop...
•Q& A..?
Thanks..!
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Java

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Transcript of "Java "

  1. 1. Java Review
  2. 2. Course Curriculum  Module 1 » Java Basics  Module 2 » Java Constructs  Module 3 » OOP Concept  Module 4 » Interfaces and Enums  Module 5 » Dynamic Data Storage  Module 6 » Threads  Module 7 » Exception Handling  Module 8 » Database & JDBC and Project
  3. 3. What is Java ? • Java - Java is not just a programming language but it is a complete platform for object oriented programming. • JRE - Java standard class libraries which provide Application Programming Interface and JVM together form JRE (Java Runtime Environment). • JDK - JDK (Java development kit) provides all the needed support for software development in Java.
  4. 4. Java Virtual Machine (JVM) • Runs the Byte Code. • Makes Java platform independent. • Handles Memory Management.
  5. 5. Byte Code • Java bytecode is the form of instructions that the Java Virtual Machine executes • A Java programmer does not need to be aware of or understand Java bytecode at all. • The model of computation of Java bytecode is that of a stack oriented programming language.
  6. 6. Garbage Collection • The programmer is not responsible for memory management in Java. • The memory area in JVM where objects are created is called Heap. • The memory is freed during runtime by a special thread called Garbage Collector. • The GC looks for objects which are no longer needed by the program and destroys them.
  7. 7. Garbage Collection
  8. 8. Garbage Collection
  9. 9. Garbage Collection
  10. 10. Garbage Collection
  11. 11. How Java works ? • Java compilers convert your code from human readable to something called “bytecode” in the Java world. • “Bytecode” is interpreted by a JVM, which operates much like a physical CPU to actually execute the compiled code. • Just-in-time (JIT) compiler is a program that turns Java bytecode into instructions that can be sent directly to the processor.
  12. 12. How Java works ?
  13. 13. Basic Java Syntax
  14. 14. Data Types in Java • Data types define the nature of a value • We need different data-types to handle real-world information Name Size (in bits) Range long 64 -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 int 32 –2,147,483,648 to 2,147,483,647 Short 16 –32,768 to 32,767 byte 8 –128 to 127 double 64 4.9e–324 to 1.8e+308 float 32 1.4e–045 to 3.4e+038 char 16 0 to 65,536 boolean ?? true/false
  15. 15. Primitive Types and Variables • boolean, char, byte, short, int, long, float, double etc. • These basic (or primitive) types are the only types that are not objects (due to performance issues). • This means that you don’t use the new operator to create a primitive variable.
  16. 16. Naming Convention of Variables • Can start with a letter, an underscore(_), or a dollar sign ($) • Cannot start with a number.  long _LongNumber = 9999999;  String firstName = “John”;  float $Val = 2.3f;  int i, index = 2;  double gamma = 1.2;  boolean value2 = false;
  17. 17. Statements & Blocks • A simple statement is a command terminated by a semi-colon: name = “Fred”; • A block is a compound statement enclosed in curly brackets: { name1 = “Fred”; name2 = “Bill”; } • Blocks may contain other blocks.
  18. 18. Flow of Control • Java executes one statement after the other in the order they are written. • Many Java statements are flow control statements: Alternation: if, if else, switch
  19. 19. Java Basic Constructs • If • If…else • Nested If…else • Switch Statement
  20. 20. If else– Syntax if ( <condition> ) { // Execute these statements if <condition> is TRUE }
  21. 21. If else– Syntax if ( <condition> ) { // Execute these statements if <condition> is TRUE } else { // Execute these statements if < condition> is FALSE }
  22. 22. If else– Syntax if ( <condition1> ) { // Execute these statements if <condition1> is TRUE } else if ( <condition2> ) { // Execute these statements if <condition2> is TRUE } else { // if both <condition1> and <condition2> is FALSE }
  23. 23. switch– Syntax switch (expression) { case cond1: block_1; break; case cond2: block_2; break; ... default: block_default; }
  24. 24. Operators • Provide a way to perform different operations on variables • Categories of Java Operators Assignment Operators = Arithmetic Operators - + * / % Relational Operators > < >= <= == != Logical Operators && || & | ^ Unary Operators + - ++ -- !
  25. 25. Assignment and Arithmetic Operators • Used to assign a value to a variable • Syntax – <variable> = <expression> • Java provides eight Arithmetic operators: – for addition, subtraction, multiplication, division, modulo (or remainder), increment (or add 1), decrement (or subtract 1), and negation. Assignment Operator =
  26. 26. Relational Operators • Used to compare two values. • Binary operators, and their operands are numeric expressions. Relational Operators > < >= <= == !=
  27. 27. Logical Operators • Return a true or false value based on the state of the variables • There are six logical operators Conditional AND Conditional OR AND OR NOT Exclusive OR Logical Operators && || & | ! ^
  28. 28. Static versus Non-static Variables • Static variables are shared across all the objects of a class – There is only one copy • Non-Static variables are not shared – There is a separate copy for each individual live object. • Static variables cannot be declared within a method.
  29. 29. •Q& A..?
  30. 30. Thanks..!

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