1. Advanced object-oriented
1. static (static is shared)
static variable
Features: Modified member variables are shared by all objects of this class
static method
Static methods can only call static things, non-static methods can call all
Notes on static
static memory map
Recognize the main method
2. Tool class, test class, javabean class
Write tool class
3. Inheritance
inheritance concept
summary
Inherited Features
Features: Supports single inheritance, does not support multiple inheritance, but supports multi-level inheritance
summary
Subclasses can only access non-private members
What content can a subclass inherit from a parent class?
Memory map of member variable inheritance
private
virtual method table
Memory graph of member method inheritance
Inheritance: member variable access characteristics (proximity principle)
summary
Inheritance: member method access features
Method override (@Override)
summary
Inheritance: access characteristics of constructors
summary
Summary of using this and super
4. Polymorphism
epistemic polymorphism
summary
Characteristics of calling members in polymorphism
Calling member variables: look at the left side when compiling, and look at the left side when running
Call member methods: compile to the left, run to the right
Advantages and disadvantages of polymorphism
summary
5. Package
6. final (constant)
7. Permission Modifier
8. Code blocks
Local code blocks (understand)
Constructing code blocks (understanding)
static block
9. Abstract classes and abstract methods
concept
Precautions
summary
10. Interface
interface writing
Characteristics of members in an interface
Relationship Between Interfaces and Classes
New method in interface
Adapter design pattern
11. Inner classes
initial inner class
member inner class
summary
static inner class
summary
local inner class
Anonymous inner class (use once) (most important)
Usage scenario of anonymous inner class (only used once)
subclass object of class
The implementation class object of the interface
summary
2. Commonly used APIs
1、Math
common method
summary
2、 System
summary
3、Runtime
4、Object
Construction method
member method
equals
clone clone
shallow clone
deep clone
summary
5、 Objects
6. BigInteger and BigDecimal
BIgInterger constructor
common method
summary
BigDecimal
decimals in computer
summary
6. Regular expressions
initial regular expression
summary
Function 1: Check whether the string meets the rules (matches)
Function 2: Crawler (Pattern) (Matcher)
text crawler
Web Crawler
Crawl data conditionally
Greedy crawling and non-greedy crawling
Use of regular expressions in string methods
group
capture packet
non-capturing packet
summary
7. time
JDK7 time class
Date class
SimpleDateFormat class
Calendar class (modified date)
JDK8 time class
Date class
ZoneId time zone
Instant timestamp
ZoneDateTime
Date formatting class DateTimeFormatter 
Calendar
Tools
8. Packaging
3. Collection advanced
1. Collection Architecture
2. Single-column collection
Single-column collection top-level collection Collection
traversal mode
iterator traversal
Enhanced for traversal
Lambda expression traversal
summary
List collection
unique method 
traversal mode
The underlying principle of ArrayList collection
Basically no use
Iterator source code
Generics in depth
generic class
generic method
Generic wildcards
Generic summary
Set series collection
hash value
The underlying principle of HashSet
The underlying principle of LinkedHashSet
TreeSet
summary
summary
3. Two-column collection
features
Common APIs
traversal mode
The first way: key lookup value
Method 2: Key-value pairs
Method 3: Lambda expression
HashMap
LinkedHashMap
TreeMap
4. Variable parameters
