30. Lambda Expression, Functional Interface, Combining Predicates

Lambda Expression A way of expressing a function (method) in a simple 'expression' form Anonymous function (function without a name) Difference between function and method Fundamentally t...

Donghyeok (Henry) Lee · 2 years ago

29. sleep(), interrupt(), suspend(), resume(), stop(), join(), Thread synchronization, wait(), notify()

sleep() Makes the current thread stop for the specified amount of time. Exception handling is required (if InterruptedException occurs, it wakes up). It is not possible to stop a specific t...

Donghyeok (Henry) Lee · 2 years ago

28. Thread, start(), run(), Daemon Thread

Processes and Threads (Process & Thread) Process (factory): An executing program composed of resources and threads. Thread (worker): Performs actual work within a process. All processes...

Donghyeok (Henry) Lee · 2 years ago

27. Enumerations, Annotations, Meta Annotations, Marker Annotation

Adding members to Enumerations For non-continuous enumeration constants, write the desired value inside parentheses (). To use parentheses (), you need to add instance variables and constru...

Donghyeok (Henry) Lee · 2 years ago

26. Iterator<E>, HashMap<K,V>, Bounded Generic Class, Constraints of Generics, Wildcard <?>, Enumeration (Enum)

Iterator<E> When creating a class, use type variables such as T instead of Object type. HashMap<K,V> If multiple type variables are needed, declare them separated by commas (,...

Donghyeok (Henry) Lee · 2 years ago

25. Collections, Generics, Generics Type, Polymorphism

Collections: Static methods for collections Fill, copy, sort, search collections - fill(), copy(), binarySearch(), etc. Synchronization of collections - synchronizedXXX() read-only collecti...

Donghyeok (Henry) Lee · 2 years ago

24. HashSet, TreeSet, Binary search tree, Tree traversal, HashMap and Hashtable, Hashing

HashSet - Unordered, No duplicates A representative collection class that implements the Set interface To maintain the order, use the LinkedHashSet class. TreeSet A collection class that...

Donghyeok (Henry) Lee · 2 years ago

23. Stack, Queue, Iterator, ListIterator, Enumeration, Arrays, Enhanced for loop, Comparator, Comparable

Stack LIFO structure, where the last stored item is the first one to be retrieved. *LIFO: last in first out. Queue FIFO structure, where the first stored item is the first one to be retrie...

Donghyeok (Henry) Lee · 2 years ago

22. SimpleDateFormat, Collection Framework, Collection Classes, ArrayList, LinkedList, Doubly Linked List, Doubly Circular Linked List

SimpleDateFormat Allows you to output dates and times in various formats. Can also extract dates and times from a string that is already formatted in a specific way. Collection Framework C...

Donghyeok (Henry) Lee · 2 years ago

21. Converting Strings to Numbers, Autoboxing, Unboxing, Date and Time & Formatting, DecimalFormat

Converting Strings to Numbers -Various ways to convert strings to numbers How to convert a string in base n to a number Autoboxing & Unboxing int → Integer: Autoboxing Integer → int:...

Donghyeok (Henry) Lee · 2 years ago

20. Join(), StringJoiner, StringBuffer, Math Class, Wrapper Class, Number Class

Join() and StringJoiner join() method combines multiple strings with a separator. Conversion between Strings and Primitive Types Ways to convert numbers to strings: number + "&quot...

Donghyeok (Henry) Lee · 2 years ago

19. Chained Exception, hashCode(), Object class, String class, Comparison between String

Chained Exception One exception can cause another exception to occur. If exception A causes exception B, then A is the cause exception of B. Reasons for Using Chained Exception To handle...

Donghyeok (Henry) Lee · 2 years ago

18. Exception Handling, Try-Catch Blocks, Finally Block, Exception Re-throwing

Exception Handling Program Errors Compilation Error Runtime Error Error: Serious error Exception: Minor error Exception and its subclasses RuntimeException and its subclasses Logical...

Donghyeok (Henry) Lee · 2 years ago

17. Default Methods, Static Methods, Inner Classes, Anonymous Classes, Exception Handling Program Errors

Default Methods and Static Methods Default and static methods can be added to interfaces (Since JDK 1.8) It is difficult to add new abstract methods to an interface. Default methods vi...

Donghyeok (Henry) Lee · 2 years ago

16. Abstract Class, Interfaces, Inheritance of interfaces

Creating an Abstract Class Abstraction ←→ Concretization Abstracted code is more flexible than concretized code. It is advantageous for changes. Interfaces A collection of abstract m...

Donghyeok (Henry) Lee · 2 years ago

15. Instanceof, Polymorphism, Abstract class

Instanceof operator Used to check whether it is possible to convert the reference variable's type (only possible between ancestors and descendants). Returns true if possible. Advantage...

Donghyeok (Henry) Lee · 2 years ago

14. Access Modifiers, Encapsulation, Polymorphism, Casting of Reference Variables

Access Modifiers Private : Only accessible within the same class Default : Only accessible within the same package. Protected : Accessible within the same package and from descendant c...

Donghyeok (Henry) Lee · 2 years ago

13. Inheritance, Object class, Overriding, Super, Package, Import, Modifiers

Single inheritance Java allows only single inheritance (C++ allows multiple inheritance) Only one important class is inherited, and the rest are included in the relationship. Object cl...

Donghyeok (Henry) Lee · 2 years ago

[MySQL] 2. Database Modeling, Data Building Process, Index, View, Stored Procedure, Trigger, Backup and Restore

Requirements Analysis, System Design, and Modeling Database Modeling The process of determining how to move data used in the real world into MySQL. Data Building Process 1)Database creatio...

Donghyeok (Henry) Lee · 2 years ago

12. Constructor this(), Reference variable this, Initialization, Inheritance, Composition

Constructor this() Used to call another constructor in a constructor Can only be used in the first line when calling another constructor Reference variable this Reference variable th...

Donghyeok (Henry) Lee · 2 years ago

11. Primitive type parameters, Reference type parameters, Static methods, Instance methods, Overloading, Constructor

Primitive type parameters Can only read the value of a variable (read-only), 8 types Reference type parameters Can read and modify the value of a variable (read & write) Static metho...

Donghyeok (Henry) Lee · 2 years ago

[MySQL] 1. DBMS, MySQL, Database, SQL

DBMS MySQL MariaDB PostgreSQL Oracle SQL Server DB2 Access SQLite MySQL A type of DBMS software developed by Oracle. Database A collection of data that is accessed and u...

Donghyeok (Henry) Lee · 2 years ago

10. Variable properties, method, return, Stack

Among the variable properties Those with individual properties are 'instance variables' e.g. the pattern and number of a card Those with common properties are 'class variables' e.g. the...

Donghyeok (Henry) Lee · 2 years ago

9. Object-Oriented Language, Class, Instance, Types of variables

Object-Oriented Language In the 1980s, software (such as C language, Fortran, and Cobol) faced a crisis where they couldn't keep up with rapid changes. Object-oriented languages were int...

Donghyeok (Henry) Lee · 2 years ago

8. Array, Two-dimensional array, Array class methods

Sum and average of an array Add up the values of each array using a loop. Divide by the length of the array. Maximum and minimum value of an array Utilize variables max, min and init...

Donghyeok (Henry) Lee · 2 years ago

7. While loop, Do-while loop, break, Array

while loop: repeats the block {} while the condition is met - used when the number of repetitions is unknown do-while loop: repeats the block {} at least once - useful when receiving user in...

Donghyeok (Henry) Lee · 2 years ago

6. Conditional Operator ?, Conditional Statement, Loop Statement, if / else if Statement, Nested if Statement, Switch Statement, for Loop

Conditional Operator ? The result of the operation varies depending on the result of the condition. result = (x > y) ? x : y ; result = (5 > 3) ? 5 : 3; → result = 5; Assignment Oper...

Donghyeok (Henry) Lee · 2 years ago

5. Type Conversion, Operators

Type Conversion Operator Type Conversion: converting the type of a variable or constant to another type (Type)Operand Automatic Type Conversion "The type is automatically converte...

Donghyeok (Henry) Lee · 2 years ago

4. Integer Overflow, Operators, Operand

Integer Overflow A calculating machine Maximum value + 1 = Minimum value Minimum value - 1 = Maximum value Conversion between Characters and Numbers Number + '0' = Character Character -...

Donghyeok (Henry) Lee · 2 years ago

3. Variable type, Constant, Literal, Scanner

Variable type The type of a variable is determined by the type of value it stores. Declare a variable with a type that matches the type of the value to be stored. Type of value Variable...

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Donghyeok (Henry) Lee

30. Lambda Expression, Functional Interface, Combining Predicates

29. sleep(), interrupt(), suspend(), resume(), stop(), join(), Thread synchronization, wait(), notify()

28. Thread, start(), run(), Daemon Thread

27. Enumerations, Annotations, Meta Annotations, Marker Annotation

26. Iterator<E>, HashMap<K,V>, Bounded Generic Class, Constraints of Generics, Wildcard <?>, Enumeration (Enum)

25. Collections, Generics, Generics Type, Polymorphism

24. HashSet, TreeSet, Binary search tree, Tree traversal, HashMap and Hashtable, Hashing

23. Stack, Queue, Iterator, ListIterator, Enumeration, Arrays, Enhanced for loop, Comparator, Comparable

22. SimpleDateFormat, Collection Framework, Collection Classes, ArrayList, LinkedList, Doubly Linked List, Doubly Circular Linked List

21. Converting Strings to Numbers, Autoboxing, Unboxing, Date and Time & Formatting, DecimalFormat

20. Join(), StringJoiner, StringBuffer, Math Class, Wrapper Class, Number Class

19. Chained Exception, hashCode(), Object class, String class, Comparison between String

18. Exception Handling, Try-Catch Blocks, Finally Block, Exception Re-throwing

17. Default Methods, Static Methods, Inner Classes, Anonymous Classes, Exception Handling Program Errors

16. Abstract Class, Interfaces, Inheritance of interfaces

15. Instanceof, Polymorphism, Abstract class

14. Access Modifiers, Encapsulation, Polymorphism, Casting of Reference Variables

13. Inheritance, Object class, Overriding, Super, Package, Import, Modifiers

[MySQL] 2. Database Modeling, Data Building Process, Index, View, Stored Procedure, Trigger, Backup and Restore

12. Constructor this(), Reference variable this, Initialization, Inheritance, Composition

11. Primitive type parameters, Reference type parameters, Static methods, Instance methods, Overloading, Constructor

[MySQL] 1. DBMS, MySQL, Database, SQL

10. Variable properties, method, return, Stack

9. Object-Oriented Language, Class, Instance, Types of variables

8. Array, Two-dimensional array, Array class methods

7. While loop, Do-while loop, break, Array

6. Conditional Operator ?, Conditional Statement, Loop Statement, if / else if Statement, Nested if Statement, Switch Statement, for Loop

5. Type Conversion, Operators

4. Integer Overflow, Operators, Operand

3. Variable type, Constant, Literal, Scanner

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Static

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Donghyeok (Henry) Lee

30. Lambda Expression, Functional Interface, Combining Predicates

29. sleep(), interrupt(), suspend(), resume(), stop(), join(), Thread synchronization, wait(), notify()

28. Thread, start(), run(), Daemon Thread

27. Enumerations, Annotations, Meta Annotations, Marker Annotation

26. Iterator<E>, HashMap<K,V>, Bounded Generic Class, Constraints of Generics, Wildcard <?>, Enumeration (Enum)

25. Collections, Generics, Generics Type, Polymorphism

24. HashSet, TreeSet, Binary search tree, Tree traversal, HashMap and Hashtable, Hashing

23. Stack, Queue, Iterator, ListIterator, Enumeration, Arrays, Enhanced for loop, Comparator, Comparable

22. SimpleDateFormat, Collection Framework, Collection Classes, ArrayList, LinkedList, Doubly Linked List, Doubly Circular Linked List

21. Converting Strings to Numbers, Autoboxing, Unboxing, Date and Time & Formatting, DecimalFormat

20. Join(), StringJoiner, StringBuffer, Math Class, Wrapper Class, Number Class

19. Chained Exception, hashCode(), Object class, String class, Comparison between String

18. Exception Handling, Try-Catch Blocks, Finally Block, Exception Re-throwing

17. Default Methods, Static Methods, Inner Classes, Anonymous Classes, Exception Handling Program Errors

16. Abstract Class, Interfaces, Inheritance of interfaces

15. Instanceof, Polymorphism, Abstract class

14. Access Modifiers, Encapsulation, Polymorphism, Casting of Reference Variables

13. Inheritance, Object class, Overriding, Super, Package, Import, Modifiers

[MySQL] 2. Database Modeling, Data Building Process, Index, View, Stored Procedure, Trigger, Backup and Restore

12. Constructor this(), Reference variable this, Initialization, Inheritance, Composition

11. Primitive type parameters, Reference type parameters, Static methods, Instance methods, Overloading, Constructor

[MySQL] 1. DBMS, MySQL, Database, SQL

10. Variable properties, method, return, Stack

9. Object-Oriented Language, Class, Instance, Types of variables

8. Array, Two-dimensional array, Array class methods

7. While loop, Do-while loop, break, Array

6. Conditional Operator ?, Conditional Statement, Loop Statement, if / else if Statement, Nested if Statement, Switch Statement, for Loop

5. Type Conversion, Operators

4. Integer Overflow, Operators, Operand

3. Variable type, Constant, Literal, Scanner