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Java
  • 자바의 역사
  • Ch1
    • Before Start Java
      • History of Java
      • Feature of Java
      • API Documentation
      • Hello World!
      • eclipse shortcut
      • Eclipse IDE
      • GitHub to eclipse
  • Ch2
    • Variable
      • Variable
    • Variable Type
    • Character and String
    • Primitive type and range
    • printf and formatter
    • Scanner
    • Overflow of Int
    • Transition between different variable types
    • Object Array
  • CH3
    • Operator
  • CH4
    • 조건문과 반복문
    • if statement
    • switch
    • Math.random()
    • for statement
    • while statement
    • break, continue, named iterated statement
  • CH5
    • Array
    • 배열 활용
    • String Array
  • OOP
    • Intro
  • Class and Object
  • Make multiple Classes in one file
  • How to use Object
  • Object Array
  • Variable type according to declared location
  • Class Variable and Instance Variable
  • Method
  • Call Stack
  • Parameter
  • Static method(Class method) and Instance method
  • (Method)Overloading
  • Constructor
  • Constructor this()
  • Reference type variable "this"
  • Initialize variable
  • Inheritance
  • Composite
  • Single Inheritance, Object Class
  • (Method)Overriding
  • super, super()
  • package, class path
  • import, static import
  • modifier
  • access modifier
  • Encapsulation
  • Polymorphism
  • reference type transition
  • instanceof operator
  • Parameter polymorphism
  • Multiple object using one array
  • Abstract Class, Abstract Method
  • Creating Abstract Class
  • Interface
  • Interface Polymorphism
  • Interface Pros
  • Default method and static method
  • Inner Class
  • Anonymous Class
  • java.lang package and useful class
    • Object class
    • hashCode(), toString()
    • String class
    • StringBuffer class
    • StringBuilder class
    • Math class
    • Wrapper class
    • Number class
    • String to Number, String to Wrapper class
    • Auto-boxing and (auto)Unboxing
  • Collection Framework
    • Collections framework
    • List, Set, Map Interface
    • List의 removeAll() 과 clear() 비교
    • List Interface - ArrayList
    • How to view Java API source
    • List Interface - LinkedList
    • Stack and Queue
    • Iterator, ListIterator, Enumeration
    • Array
    • Comparator와 Comparable
    • Stack
    • String
    • String + char = String
    • String.toCharArray()
    • BufferedReader / BufferWriter
    • Scanner로 String 입력 - next( )와 nextLine( )
    • 공백없이 2차원배열 데이터 String으로 한번에 한줄씩 입력받기(문자/숫자)
    • 공백을 사이에 두고 빠른 2차원 배열 입출력
    • arr[index++]과 arr[index] index++의 차이
    • int와 long의 차이
    • Untitled
    • 타입 간의 변환
    • Array 와 ArrayList
    • valueOf()
    • Char
    • 변수, 객체 초기화(초기값 설정)
  • error troubleshooting
    • No enclosing instance of type
    • ASCII Code Table
    • java.lang.NumberFormatException
    • No enclosing instance..
  • reference
    • String을 생성하는 2가지 방법과 차이점
    • StackOverflowError(스택, 힙 메모리)
    • swtich-case 반복문
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  1. Collection Framework

타입 간의 변환

문자열 <=> 정수, 문자 <=> 정수

PreviousUntitledNextArray 와 ArrayList

Last updated 3 years ago

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  1. 정수 <=> 문자 1) 정수 -> 문자 : 3 + '0' = '3'(문자) 2) 문자 -> 정수 : '3' - '0' = 3(숫자)

  2. 문자열 <=> 정수 1) 정수 -> 문자열 : 7 + "" = "7"(문자) 2) 문자열 -> 정수 : Integer.parseInt("10")

char(문자)에서 '_' 를 빼면 정수가 된다! 아스키코드값 뺄셈이 되기 때문이다! A-'A' = 0 B-'A' = 1 A-'D' = -3

int x = sc.next().charAt(0);//x=A 일때 정수형 x값은 A의 아스키값인 97이된다!

ASCII CODE