Chapter 1 contains the basic introduction to the Java language such as

• What is Java?
• History and Features of Java
• C++ vs Java
• Hello Java Program
• Internal How to set the path?
• JDK, JRE, and JVM (Java Virtual Machine)
• JVM Memory Management
• Internal details of JVM
• Unicode System,
• Operators
• Keywords
• Control Statements like if-else, switch, for loop, while loop, etc.

Chapter 2 deals with the most important and core concepts of Java. They are:

• Naming convention of Java
• Classes, Objects, and Features. It explains how to declare a class, how to create an object in Java.
• Object declaration and initialization
• Life cycle of an object
• Anonymous object in Java

• How to declare a package.
• Package naming conventions
• Sub packages
• Types of packages, such as user-defined packages, built-in packages
• Importing packages in Java

• Data types in Java
• Primitive data types
• Non-primitive data types
• Memory allocation of primitive and non-primitive data types, etc.

• Variable declaration & initialization
• Naming convention
• Types of variables such as local variables, instance variables, and static variables
• Scope and memory allocation of variables.

• What is a method in Java
• Use of method in Java
• Method declaration, method signature
• Types of methods in Java: predefined method, user-defined methods: instance method, static method
• Calling of method
• Java main method
• Return type

• What is Constructor in Java?
• Types of constructors: Default and Parameterized constructors
• Java constructor overloading
• Constructor chaining in java
• Copy constructor in Java

8. Modifiers in Java

• What is Access modifier and Non-access modifier in Java?
• Types of access modifiers like private, default, protected, and public
• Types of non-access modifiers like abstract, final, native, static, Strictfp, synchronized modifier, transient, volatile.

• What is static keyword?
• Static variable
• Static method
• Static initialization block
• Instance initialization block
• Static nested class
• Difference between static variable and instance variable, static method and instance method, static block, and instance block.

• Final keyword
• Final variable
• Final method
• Final class

• What is Inner class in Java?
• Properties of inner class
• Instantiating inner class.
• Types of inner class in Java: normal inner class, method local inner class, anonymous inner class, and static nested class

• Super keyword
• Calling of superclass instance variable
• Superclass constructor
• Superclass method.

The second section deals with

• This keyword
• Calling of current class constructor, and method
• Difference between super and this

In this chapter, you will learn the most important topic Object-oriented programming system (OOPs). In the OOPs concept, you will learn class, object, encapsulation, inheritance, polymorphism, and abstraction. All topics are very important for interview purposes.

• Encapsulation in Java
• How to achieve Encapsulation
• Data hiding
• Tightly encapsulated class
• Getter and setter method in Java
• Naming convention of getter and setter method

• Inheritance in Java
• Is-A Relationship
• Aggregation and Composition (HAS-A)
• Types of inheritance: single level, multilevel, hierarchical, multiple, and hybrid inheritance

• Polymorphism in Java
• Types of polymorphism: Compile-time polymorphism and Run-time polymorphism
• Static and Dynamic Binding
• Method overloading
• Method overriding
• Rules of method overloading and method overriding, various example programs related to rules of overloading and overriding.
• Covariant Return type

• Abstraction in Java
• Abstract class
• Abstract method
• Interface in Java
• Nested interface, rules, and example programs.

This chapter deals with garbage collection in Java.

• FileOutputStream, FileInputStream
• BufferedOutputStream, BufferedInputStream
• SequenceInputStream
• ByteArrayOutputStream, ByteArrayInputStream
• DataOutputStream, DataInputStream
• Java FilterOutputStream, Java FilterInputStream
• Java ObjectStream, Java ObjectStreamField
• Console
• FilePermissionWriter, Reader, FileWriter, FileReader
• BufferedWriter, BufferedReader
• CharArrayReader, CharArrayWriter
• PrintStream, PrintWriter
• OutputStreamWriter, InputStreamReader
• PushbackInputStream, PushbackReader
• StringWriter, StringReader
• PipedWriter, PipedReader
• FilterWriter, FilterReader, File FileDescriptor, RandomAccessFile, and java.util.Scanner.

• Exception handling in Java
• Try-catch block
• Multiple catch block
• Nested try block
• Finally block
• Throw keyword
• Throws keyword
• Throw vs Throws, Final vs Finally vs Finalize
• Exception handling with method overriding
• Java custom exceptions
• Throwable class
• Errors
• Example Programs based on the above topics

• Java Array
• Types of array: single dimensional array, multidimensional array, declaration, instantiation, and initialization of Java array
• Passing array to a method
• Anonymous array
• Cloning an array

• String
• Immutable String
• String Comparision
• String concatenation
• Substring
• StringBuffer class
• StringBuilder class
• toString method
• StringTokenizer class

• What is thread in Java?
• Java multithreading
• Multithreading
• life cycle of a thread creating
• Thread scheduler
• Sleeping a thread, Start a thread twice
• Calling run() method
• Joining a thread
• Naming a thread
• Thread priority,
• Daemon thread
• Thread pool
• Thread group
• Shutdownhook
• Java Synchronization: synchronized method, synchronized block, static synchronization
• Deadlock
• Inter-thread Communication
• Interrupting Thread