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File	Date	Author	Commit
collections&generics	2025-06-22	0x50-0x42	[f684c5] Wildcard
exceptionHandling	2025-09-09	0x50-0x42	[b5f55c] Exception rules
inheritance&polymorphism	2025-04-23	0x50-0x42	[13b1a4] removed
interfaces&polymorphism	2025-06-17	0x50-0x42	[6b73d1] An important note on polymorphism
lambdas&streams	2025-07-08	0x50-0x42	[8d6549] Pool Puzzle
life&death_of_an_object	2025-05-02	0x50-0x42	[de1693] How long does an object live?
numbers&statics	2025-05-11	0x50-0x42	[12a7c2] Be The Compiler
.gitignore	2025-06-21	0x50-0x42	[3002ab] ignore
README.md	2025-09-03	0x50-0x42	[9e84ba] read me

Read Me

Learning Java

This repo will contain only programs.

Contents

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Inheritance and Polymorphism

1/ → Inheritance.
2/ → Polymorphism.
3/ → Method overriding.

Interfaces and Polymorphism

1/ → Weird animals.
2/ → Abstract and concrete class.
3/ → Abstract methods.
4/ → Object class.
5/ → The price of using polymorphic references of type Object.
6/ → Problems with Object.
7/ → Inner Object.
8/ → Casting an object reference back to its real type.
9/ → How much Java cares about the methods in the class of the reference variable.
10/ → Multiple inheritance in Java.
11/ → Different classes implementing the same interface.
12/ → Interfaces as polymorphic types.
13/ → Invoking the superclass version of a method.
14/ → One more thing about interfaces.
special/ → An important note on polymorphism.

Life and and Death of an object

1/ → Where things live.
2/ → Where do instance variables live.
3/ → Constructors.
4/ → Parameterized constructors.
5/ → Constructor overloading.
6/ → Constructor overloading.
7/ → Constructors and inheritance.
8/ → Invoking a superclass constructor.
9/ → Superclass constructors with arguments.
10/ → Invoking one overloaded constructor from another.
11/ → How long does an object live?
12/ → How long does an object live?

Numbers and Statics

1/ → static methods--Math methods.
2/ → difference between regular and static methdods.
3/ → class with private constructor and static methods.
4/ → static methods and non-static members.
5/ → static variables.
6/ → initializing a static variable.
7/ → static final variables.
8/ → final used with non-static variables.
9/ → looking at some Math methods in Java.
10/ → wrapping a primitive.
11/ → wrapping a primitive.
12/ → autoboxing.
13/ → turning a String into a primitive number.
14/ → turning a primitive into a String.
15/ → number formatting.
16/ → the format specifier.
17/ → static imports.
brainBarbell/ → brain barbell.
SharpenYourPencil/ → Will this code compile?....
beTheCompiler/ → be the compiler.

Collections and Generics

1/ → The diamond operator and sorting in alphabetical order.
2/ → Generic class.
3/ → Generic methods.
4/ → Sorting Song objects.
5/ → Implementing the Comparable interface.
6/ → Using a custom Comparator.
7/ → Sorting only using Comparators.
8/ → SAM or functional interfaces.
9/ → Removing duplicates -- Using HashSet -- didn't work.
10/ → Reference equality.
11/ → Object equality.
12/ → How a HashSet checks for duplicates.
13/ → Java Object Law for hashCode() and equals().
14/ → TreeSet in Java.
15/ → TreeSet using Comparator.
16/ → TreeSet with lambda functions.
17/ → How TreeSet sorts its data.
18/ → More about TreeSet.
19/ → Map in Java.
20/ → Unmodifiable list.
21/ → Convenience factory methods.
22/ → Using polymorphic arguments and generics.
23/ → Incompatibility among List objects holding supertypes and subtypes.
24/ → Wildcard.
25/ → Using the method's generic type parameter.
26/ → Methods using wildcard.
Difference

Comparable/ → Using Comparable to sort Songs.
Comparator/ → Using Comparator to sort Songs.
GenericWithT/ → The added benefit of using the generic type parameter.
GenericWithWildcard/ → Using wildcard.

generics/ → List of subtypes accepted by method using generics.
important/ → Important.
important_hashCode_equals/ → Equality of objects.
sharpenYourPencil/ → Sharpen you pencil.
Generics

genericClass/ → Important notes on generic classes.
genericMethod/ → Important notes on generic methods.

Wildcard → Important notes on wildcars.
Collection_API.png → Interfaces and classes in Collection API.
JavaObjectLaw.png → Java Object Law for hashCode() and equals().

Lambdas and Streams

1/ → forEach() in Java.
2/ → Getting started with Stream.
3/ → Chaining Stream operations.
4/ → Stacking and combining the Stream operations.
5/ → Customizing the building blocks.
6/ → Guidelines for working with streams.
7/ → Do stream operations change the original list?
8/ → Basics of lambda expressions.
9/ → Lambda expressions.
10/ → Lambda expressions.
11/ → Multiline lambda expressions.
12/ → More on lambda expressions.
13/ → Parameters in lambda expressions.
14/ → How to know if a method takes a lambda expression.
15/ → Stream operations.
16/ → Method references.
17/ → Collecting results in different ways.
18/ → More terminal operations.
19/ → Using the Optional wrapper class.
20/ → An example demonstrating the use of the Optional wrapper class.
PoolPuzzle/ → Pool Puzzle.
Project/ → A Mini Project: Understanding how to use lambda expressions.
AnatomyOfLambdaExpression.png → Anatomy of lambda expressions.
StreamOperations.png → Stream operations.

Additional links

More links

MidiSystem in Java.

printf in Java.
More on printf.