Chapter 4     

Keywords and Data type in Java

There are 32 keywords in Java language
1. abstract
2. assert
3. boolean
4. break
5. byte
6. case
7. catch
8. char
9. class
10. const
11. continue
12. default
13. do
14. double
15. enum
16. else
17. extends
18. false
19. final
20. finally
21. float
22. for
23. goto
24. if
25. implements
26. import
27. instanceof
28. int
29. interface
30. long
31. native
32. new
33. null
34. package
35. private
36. protected
37. public
38. return
39. short
40. static
41. strictfp
42. super
43. switch
44. synchronized
45. this
46. throw
47. throws
48. transient
49. true
50. try
51. void
52. volatile
53. while

⦁ False, null and true will be treat as a value.
⦁ Java language supports Unicode.

⦁ syntax for deceleration of a variable.
DataTypeName VariableName;
e.g. : int var;
⦁ If the constant is to represent a long integer value, it must be suffixed with L or l and float value must be suffixed with f. Because default integer data type is int and default real data type is double.
⦁ In java language integer constant can be specified into following formats.
a. For Decimal format simply write that number like 172.
b. For Binary format use 0b as post fix like 0b110010.
c. For Octal format use 0 as post fix like 0372.
d. For Hexadecimal format use 0x as post fix 0x18A.

Comments

Post a Comment

Popular posts from this blog

Chapter 3        First Program in Java ⦁ Syntax for deceleration of class access specifier class ClassName { /* Body of class is followed by curly bracket*/ } ⦁ An outer class can be followed by either public access specifier or default access specifier. ⦁ Name of class and name of source code must be same. ⦁ The main() function must follow the following prototype : public static void main (String [] args) { // Body of main() function } ⦁ Code of HelloWorld.java class HelloWorld { public static void main (String [] args) { System.out.println("Hello World"); } } Comments :- a. Here System is a predefined class. b. out is a static member reference variable of System class which contains address of an variable of PrintStream class. c. println() is a member function of PrintStream class. Output :- Hello World ⦁ We have to write an access specifier with every member in a class.
Read more
Chapter 5                     Type conversion in Java The process through which we convert value of one data type into another data type is called as Type Conversion. ⦁ If we want to store a value of lower size data type value into higher size data type variable  e.g. float a=3; it is permissible in java language. this type of the conversion is called widening conversion. ⦁ We cannot directly assign a higher size data type variable e.g. int a=3.5; //error syntax to assign higher size data type value into lower size data type variable                                             HigherSizeDatatype variable=(lowersizedat type) value ; e.g. int a=(int)3.5; ⦁ It will assign integer part of 3.5 which is 3 to a.    
Read more
Image
Chapter 2        Compilation and Execution of a Java Program ⦁ Java Language uses only one compiler javac.exe for all platforms. ⦁ After compilation of a java program every class in source code will convert into individual Byte code. ⦁ A Byte code can be execute on any operating system with help of Java Virtual Machine (JVM). ⦁ JVM consists an Interpreter (which is  Just-in-time compiler) can can convert Byte code into operating system readable form. ⦁ JVM differs fro compiler to compiler. ⦁ Java Developer Kit (Jdk) contains tools needed to develop the java program like compiler (javac.exe), Application Launcher (java.exe), etc. ⦁ Java Runtime Environment (Jre) contains JVM and Java package Classes (Java library). ⦁ Code for compilation a java program on command prompt : javac FileName.java ⦁ Code for execution of java program on command prompt : java FileName
Read more