20일차 강의 정리
1. Calendar Class
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 | import java.util.Calendar; public class Ex02 { public static void main(String[] args) { //캘린더 Calendar now; now = Calendar.getInstance(); int year = now.get(Calendar.YEAR); System.out.print(year+"년 "); int month = now.get(Calendar.MONTH); System.out.print(month+1+"월 "); int day = now.get(Calendar.DATE); System.out.print(day+"일 "); int week = now.get(Calendar.DAY_OF_WEEK); char[] weeks={'일','월','화','수','목','금','토'}; System.out.println(weeks[week-1]+"요일"); int ampm = now.get(Calendar.AM_PM); if(ampm==0){ System.out.print("AM "); }else{ System.out.print("PM "); } int hour = now.get(Calendar.HOUR); System.out.print(hour+":"); int min = now.get(Calendar.MINUTE); System.out.print(min+":"); int sec = now.get(Calendar.SECOND); System.out.println(sec); int hhour = now.get(Calendar.HOUR_OF_DAY); System.out.println(hhour+":"+min+":"+sec); int cntDay = now.get(Calendar.DAY_OF_YEAR); System.out.println(cntDay+"일째 입니다."); now.set(year, month, 4); } } | cs |
결과
2. Date Class
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 | import java.text.SimpleDateFormat; import java.util.Date; public class Ex03 { public static void main(String[] args) { //Date Date now = new Date(); System.out.println(now); System.out.println(now.toString()); System.out.println("-------------------------------"); SimpleDateFormat sdf; sdf = new SimpleDateFormat("yyyy년 mm월 dd일 hh시 mm분 ss초"); String kor = sdf.format(now); System.out.println(kor); System.out.println(now.getMonth()); //월 은 0부터시작해서 이번달이 7월이면 6이 출력 System.out.println(now.getTime()); } } | cs |
결과
3. Random Class
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | import java.util.Random; public class Ex04 { public static void main(String[] args) { //Random double ran = Math.random(); System.out.println(ran); Random ran2 = new Random(); System.out.println(ran2.nextInt()); //int자료형의 표현 범위 내에서 난수발생 System.out.println(ran2.nextLong()); //long자료형의 표현 범위 내에서 난수발생 System.out.println(ran2.nextDouble()); //= Math.random() //0~9난수 System.out.println(ran2.nextInt(10)); //0<=ran2<인자 //1~45 System.out.println(ran2.nextInt(45)+1); } } | cs |
결과
4. Arrays Class
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | import java.util.Arrays; public class Ex05 { public static void main(String[] args) { //Arrays int[] arr1 = {30,45,20,3,1,35}; Arrays.sort(arr1); //정렬 for (int i = 0; i < arr1.length; i++) { System.out.print(arr1[i]+" "); } System.out.println(); int[] arr2 = new int[10]; Arrays.fill(arr2, 11); Arrays.fill(arr2, 3,5,3); //arr2에서 자리번호 3~5까지 2로 채워넣는다 for (int i = 0; i < arr2.length; i++) { System.out.print(arr2[i]+" "); } } } | cs |
결과
응용 소스
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 | import java.util.Arrays; public class Ex06 { public static void main(String[] args) { int[] lotto = {30,45,20,3,1,35}; Arrays.sort(lotto); //정렬 int idx = Arrays.binarySearch(lotto, 30); System.out.println("30의 자리위치: "+idx); int[] arr2 = Arrays.copyOfRange(lotto, 1,3); //복사-> 자리번호1에서 3이전까지 System.out.println(Arrays.toString(arr2)); //복사한것 출력 System.out.println("===================================="); String[] names={"홍길동","김만수","김철수","고경아"}; System.out.println(Arrays.toString(names)); //정렬 전 Arrays.sort(names); //binarySearch하기위해 필요(정렬) int idx2 = Arrays.binarySearch(names, "김만수"); System.out.println("\'김만수\'의 자리 위치: "+idx2); System.out.println(Arrays.toString(names)); //정렬 후 System.out.println("===================================="); System.out.println("===================================="); // String[] arr = Arrays.copyOf(names, names.length); //복사, 몇번까지 String[] arr = Arrays.copyOfRange(names, 1,3); //복사 자리번호1에서 3전까지 names[1]="바꿈"; System.out.println(Arrays.toString(arr)); System.out.println(Arrays.toString(names)); } } | cs |
결과
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