Here is the approximate study plan I followed while learning Java at university. These topics were spread out over two years for me, but below I condensed them to 25 weeks based on what I think is a good pace. This study guide can be used as a checklist while learning Java individually or as part of a course.
Week 1:
Getting started
- Learn about the CLASSPATH system variable and how to set it based on the operating system
- Learn about how comments are written (inline comments and multi-line comments)
- Understand the purpose and syntax of the main method
- Learn how to compile and run programs both using an IDE and command line (using java and javac commands)
- Write Java programs that output messages to the terminal
- Understand the difference between print and println
Variables
- Understand the purpose of variables
- Be introduced to primitive types (boolean, char, byte, short, long, float, double), and String
- Learn how to declare and assign variables
Arithmetic expressions
- Understand how arithmetic expressions are used to perform calculations
- Understand how the result of the division operator depends on the types of its operands (i.e. integer vs. non-integer division)
- Learn about post- and pre-decrement/increment operators
- Learn how to concatenate Strings using +
- Become familiar with operator precedence in expressions
- Understand how brackets can be used in computing expressions
Week 2:
Using methods
- Learn how to call a method
- Learn about method signatures
- Be introduced to the class java.util.Random
- Be introduced to some methods of the classes java.lang.Math and java.lang.String
Keyboard Input
- Learn how to write programs that accept keyboard input from the user
- Learn about the class java.util.Scanner and how to use its methods like nextLine() and nextInt()
Week 3:
Boolean expressions
- Understand relational operators such as >,>=, <, <=, ==, and !=
- Write Boolean expressions using relational operators
- Use logical operators such as &&, ||, and !
Conditional statements
- Learn about if, elseif, and else
- Learn about switch statements
- Understand the ternary operator in Java
Week 4, 5:
Loops
- Understand that loops are used to program repetition
- Understand the syntax and semantics of for and while loops
- Become familiar with nested loops
- Learn how to use break to force exit from a loop
- Be introduced to the keyword ‘continue’
- Learn about the enhanced for loop
Formatting Strings
- Learn to use String.format()
- Learn about printf
Week 6:
More about methods
- Be introduced to the difference between static and non-static methods
- Understand the difference between void and non-void methods
- Understand method overloading
Week 7:
One-dimensional arrays:
- Learned how to declare and initialize an array
- Use loops to go through arrays
- Learn about array index out of bounds exceptions
Week 8, 9:
Defining methods
- Learn how to define void static methods
- Learn how to define non-void static methods
- Learn how to use parameters
- Learn about return types
Week 10:
Command-line arguments
- Learn how to use command-line arguments
Recursion
- Learn how to define and use recursive methods
Week 11:
Packages
- Learn how to package programs
- Learn how to import classes from packages
Week 12:
More about variables
- Understand local variables
- Understand the scope of variables
- Distinguish between simple vs. reference types
- Java uses pass-by-value
Type casting
- Understand that variables of different types have different sizes
- Understand type casting (implicit vs. explicit casting)
Week 13:
Files
- Understand how to read a file character by character
- Understand how to read a file line by line
- Learn how to write to a file
Week 14, 15:
Classes
- Be able to define classes
- Understand how to use constructors
- A default constructor is provided only if custom constructors are not defined
- Become familiar with instance variables and instance methods
- Learn about the toString() method
- Be able to create instances of classes
Week 16:
Inheritance
- Be able to extend classes
- Understand the use of the keyword ‘super’
- Learn about method overriding
Week 17:
Exception handling
- Handle exceptions using try/catch blocks
- Understand what it means to throw an exception
- Be introduced to checked vs. unchecked exceptions
Week 18:
Basic data structures
- ArrayList
- LinkedList
- HashMap
- HashSet
StringBuilder
- Understand the difference between String and StringBuilder
Week 19:
Objects
- Understand that objects know and do things — instance variables represent the state of an object, methods represent the behavior of an object
- Be introduced to the garbage-collectible heap
Object-oriented programming
- Be introduced to concepts related to object-oriented programming: abstraction, data hiding, polymorphism, inheritance, and dynamic binding
Week 20:
Reference types
- A reference variable may be active or null
- Objects may be reachable or abandoned
- An object is abandoned when the reference goes out of scope permanently, the reference is reassigned, or the reference is set to null
- The JVM divides the memory into two parts: the stack and the heap.
- Local variables, i.e. those that are declared within methods, live on the stack
- Instance variables live on the heap with their containing object
Week 21:
Abstraction
- Learn about abstract classes
- Learn about abstract methods
- Learn about interfaces
- Understand that Java only supports single inheritance
- Understand that a class may implement one or more interfaces with the keyword ‘implements’
Week 22:
Final keyword
- Understand that Java constants are marked with ‘static final’
- A final variable cannot be changed after it is initialized
- A final method cannot be overridden
- A final class cannot be extended
Boxing and unboxing
- Each primitive type has a class dedicated to it — these classes are known as wrappers
- Learn about boxing and unboxing
- Autoboxing and auto-unboxing are automatic wrapping and unwrapping done by the Java compiler
Week 23:
Streams
- Distinguish between connection streams and chain streams
- Connection streams represent a connection to a source or destination and must be chained to another stream
- Chain streams cannot connect to a source or destination
- A FileWriter connection stream can be chained to a BufferedWriter for efficient writing
- A FileReader connection stream can be chained to a BufferedReader for efficient reading
Week 24:
Serialization
- The state of a Java object (i.e. its instance variables) can be saved using serialization
- Objects, or their super class, must implement Serializable if they are to be serialized
- An object is serialized to a file by chaining a FileOutputStream to an ObjectOutputStream. Objects are written using write()
- Static variables are not serialized
- A transient instance variable will not be serialized
- An object’s state can be restored from a file by chaining FileInputStream to ObjectInputStream. The objects are read using readObject() in the order in which they were serialized
Week 25:
Threads
- Understand what is meant by multithreading
- A thread can be in one of four states: NEW, RUNNABLE, RUNNING and BLOCKED
- Learn how threads can be created in Java
- Understand that concurrency problems can occur in multithreaded programs
- The keyword synchronized can be used to make methods (and even statements) thread-safe
- Understand that synchronization also has problems (e.g. deadlock)
Feel free to reach out to me for a chat or if you have any questions/comments/suggestions :)
