15일차 강의 정리


래퍼클래스

1. Integer

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public class Ex01 {
    public static void main(String[] args) {
        //Wrapper class
        //integer
        Integer i = 123;    //오토박싱(자동으로 객체를 씌우는것)<->언박싱
        
        int a=(int)2147483647;    //원시자료형
        Integer one = new Integer(3);
        Integer one2 = new Integer(a);    //정수실수형 문자열
        Integer one3 = new Integer("3");
        Integer one4 = one2+one3;
        int one5= one2.intValue()+one3.intValue();
        one4 = new Integer(one5);
        int one6 = Integer.valueOf("234");    //return 타입이 int
        
        System.out.println(one4.doubleValue());        //.intValue() 이것은 자동으로 
        System.out.println(Integer.MAX_VALUE);
        System.out.println(Integer.MIN_VALUE);
        System.out.println(Integer.SIZE);
        System.out.println(one.intValue()==one3.intValue());
 
        System.out.println("------------------------");
        System.out.println(one6);
        System.out.println(one3.compareTo(one));    //같으면 0 ,3가 크면 1,작으면 -1
        System.out.println(Integer.reverse(9));    //?
        System.out.println(Integer.toBinaryString(4));    //2진수로 반환(문자열로 반환된다)
        System.out.println(Integer.toOctalString(8));    //8진수로 반환
        System.out.println(Integer.toHexString(19));    //16진수
    }
}
 
class Integ{
    int a;
    public Integ(int a){
        this.a=a;
    }
    public Integ(String st){
        this.a=Integer.parseInt(st);
    }
}
cs

2. char

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public class Ex02 {
    public static void main(String[] args) {
        //char
//        Character ch = new Character('a');
        
//        System.out.println(Character.isDigit('+'));        //숫자 인지 확인
//        System.out.println(Character.isLetter('a'));    //문자 인지 확인
//        System.out.println(Character.isUpperCase('A'));    //문자이면서 대문자인지
//        System.out.println(Character.isLowerCase('a'));    //소문자인지
//        System.out.println(Character.isSpace('a'));        //공백인지
//        System.out.println(Character.isDefined(' '));    //유니코드인지
        
        char[] ch = {'함','a','A','!',' ','5'};
        for(int i=0;i<ch.length;i++){
            
            System.out.print(ch[i]+"는 ");
            if(Character.isDefined(ch[i])){
                System.out.println("유니코드인  ");
            }
            if(Character.isUpperCase(ch[i])){
                System.out.print("대");
            }
            if(Character.isLowerCase(ch[i])){
                System.out.print("소");
            }
            if(Character.isLetter(ch[i])){
                System.out.println("문자입니다");
            }
            if(Character.isDigit(ch[i])){
                System.out.println("숫자입니다.");
            }
            if(Character.isWhitespace(ch[i])){
                System.out.println("공백문자입니다.");
            }
        }
    }
}
cs

3. boolean

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public class Ex03 {
    public static void main(String[] args) {
        // boolean
        Boolean boo = new Boolean(Boolean.TRUE);
        Boolean boo2 = new Boolean("false");
 
        if(boo2.booleanValue()){
            System.out.println("참입니다");
        }else{
            System.out.println("거짓입니다.");
        }
    }
}
cs

4. byte

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public class Ex04 {
    public static void main(String[] args) {
        //byte
        Byte by1 = new Byte("1");
        Byte by2 = new Byte("2");
        byte a = (byte)1;
        byte b = (byte)2;
        byte c = (byte)((int)a+(int)b);
        
//        Byte by3 =(Byte)((byte)(by1.byteValue()+by2.byteValue()));
//        System.out.println(by3+3);
        Byte by3 =new Byte((byte)(by1.byteValue()+by2.byteValue()));
        System.out.println(by3+3);
 
        System.out.println((byte)(Byte.MAX_VALUE+1));
        
        Short sh1 = Short.MAX_VALUE;
        Short sh2 = Short.MIN_VALUE;
        System.out.println(sh1);
        System.out.println(sh2);
        
        Long lo1 = new Long(9223372036854775806l);
        System.out.println(lo1);
        System.out.println(lo1.intValue());
        System.out.println(Long.toBinaryString(lo1));
        System.out.println(Long.toOctalString(lo1));
        System.out.println(Long.toHexString(lo1));
        Long lo2 = Long.MAX_VALUE;
        Long lo3 = Long.MIN_VALUE;
        System.out.println(lo2);
        System.out.println(lo3);
    }
}
cs

5. float

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public class Ex05 {
    public static void main(String[] args) {
        //Float
        Float f1 = new Float(10.0/3);
        
        System.out.println(f1);
        System.out.println(f1.byteValue());
        System.out.println(f1.intValue());
        System.out.println(f1.floatValue());
        System.out.println(f1.doubleValue());
        System.out.println(f1.isInfinite());
    }
}
cs


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