[JAVA] wrapper

기본형	래퍼클래스	생성자	활용예
boolean	Boolean	Boolean(boolean value)  Boolean(String s)	Boolean b = new Boolean(true); Boolean b 2= new Boolean("true");
char	Character	Character(char value)	Character c = new Character('a');
byte	Byte	Byte(byte value)  Byte(String s)	Byte b = new Byte(10); Byte b2 = new Byte("10");
short	Short	Short(short value)  Short(String s)	Short s = new Short(10); Short s2 = new Short("10");
int	Integer	Integer(int value)  Integer(String s)	Integer i = new Integer(100); Integer i2 = new Integer("100");
long	Long	Long(long value)  Long(String s)	Long l = new Long(100); Long l2= new Long("100");
float	Float	Float(double value)  Float(float value)  Float(String s)	Float f = new Float(1.0); Float f2 = new Float(1.0f); Float f3 = new Float("1.0f");
double	Double	Double(double value)  Double(String s)	Double d = new Double(1.0); Double d2 = new Double("1.0");

주의 : 생성자의 매개변수로 문자열을 제공할 때, 각 자료형에 알맞은 문자열을 사용해야한다.

예) new Integer("1.0");  ->  NumberFormatException 발생

- 적용
boolean boo1=true;
Boolean boo2=new Boolean("false"); //Deprecated 절판
Boolean boo3=true;

System.out.println(boo1);
System.out.println(boo2);
System.out.println(boo3);
System.out.println(boo3.toString());//"true"
///////////////////////////////////////////////////////

int in1=3;
Integer in2=new Integer(5);
Integer in3=7;

System.out.println(in1);
System.out.println(in2);
System.out.println(in3);

System.out.println(in2.toString());		//"5"
System.out.println(in3.doubleValue());  //7.0

System.out.println(Integer.toBinaryString(15)); //"1111"
System.out.println(Integer.toOctalString(15));	//"17"
System.out.println(Integer.toHexString(15));	//"f"

System.out.println(Integer.sum(2, 4)); //6
System.out.println(Integer.max(2, 4)); //4
System.out.println(Integer.min(2, 4)); //2

//★★★
System.out.println(Integer.parseInt("123")); //"123" -> 123 변환

//NumberFormatException 발생
//System.out.println(Integer.parseInt("KOREA"));
////////////////////////////////////////////////////////////////

long lo1=3L;
Long lo2=new Long(5);
Long lo3=7L;

double dou1=2.4;
Double dou2=new Double("3.5");
Double dou3=6.7;

//문)실수형값들 중에서 정수의 합을 구하시오 (2+3+6)
int hap=(int)dou1+dou2.intValue()+dou3.intValue();
System.out.println(hap);//11
//////////////////////////////////////////////////

char ch1='R';
Character ch3=new Character('a');
Character ch2='m';

System.out.println(ch1);
System.out.println(ch2);
System.out.println(ch3);

System.out.println(Character.isWhitespace(' '));
System.out.println(Character.toLowerCase('R'));
System.out.println(Character.toUpperCase('a'));