Java Refresher Notes

📘 Step-by-step Java learning notes covering everything from fundamentals to J2EE and web apps. Includes concepts, examples, and explanations in easy-to-read Markdown format.

📂 Contents

1. Intro
2. Differences Between JDK, JRE and JVM
3. Data Types
4. Operators
5. OOPs (Object Oriented Programming)
6. Variables
7. Loops
8. Arrays
9. Functions (methods)
10. this keyword
11. Types of functions
12. Method Overloading (Compile time polymorphism)
13. var args
14. Passing object as argument
15. Passing Array of Objects to a method
16. Returning Value by a Method
17. Print an array element by element
18. Passing Objects as Arguments
19. String
20. Wrapper Class
21. Boxing, Unboxing, Autoboxing
22. String Class
23. Character Class
24. Date Class
25. String Handling
26. Typecasting
27. Java Scanner Class
28. Email Validation
29. Switch-Case Statement
30. StringBuffer Class
31. StringBuilder Class
32. Mutable string
33. Substring
34. Constructor
35. Types of Constructors
36. Access Modifiers
37. Getter and Setter Methods
38. Constructor Overloading
39. ASCII (American Standard Code for Information Interchange)
40. Inheritance
41. Polymorphism (Method Overriding – Runtime Polymorphism)
42. super keyword
43. Abstraction
44. Anonymous Class
45. Encapsulation
46. Interface
47. Abstract Class vs. Interface
48. Exception Handling
49. Inner Classes (Nested Classes)
50. File Handling
51. File class
52. Multithreading
53. Runnable Interface
54. isAlive() Method
55. Life Cycle of a Thread (Thread States controlled by JVM)
56. Synchronization
57. Inter-Thread Communication (ITC)
58. API (Application Programming Interface)
59. JDBC (Java Database Connectivity)
60. DriverManager Class
61. Connection interface
62. Statement interface
63. ResultSet interface
64. PreparedStatement Interface
65. Collections
66. List Interface
67. ArrayList Class
68. LinkedList Class
69. Difference between ArrayList and LinkedList
70. Garbage Collection
71. Finalize method
72. Serialization
73. J2EE Web application
74. Web Architecture and Network Basics
75. Servlet Fundamentals and Lifecycle
76. MVC (Model View Controller)
77. Servlet Interface functions
78. Content Types in HTTP and MIME
79. Servlet API
80. Servlet Interface
81. Steps to create a servlet
82. HttpServlet class
83. GET vs. POST
84. GenericServlet Class
85. ServletRequest interface
86. CRUD in Servlet
87. Servlet Collaborations : RequestDispatcher, sendRedirect
88. ServletConfig Interface
89. ServletContext Interface
90. Attribute in Servlet
91. State Management
92. Session Tracking in Servlets
93. Servlet with Annotation
94. HTTP Session
95. Cookie Class
96. Hidden Form Field
97. Lambda Expression
98. HashMap
99. CAPTCHA
100. MD5
101. JSP
102. JSP Implicit Objects
103. Types of JSP tags
104. EL (Expression Language)
105. JSP Lifecycle
106. JSP Elements