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package Practice.ggang9.Chapter3; | ||
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public class ArrayPractice { | ||
public static void main(String[] args) { | ||
int[] odds = {1, 3, 5, 7, 9}; | ||
String[] weeks = {"월", "화", "수", "목", "금", "토", "일"}; | ||
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weeks = new String[7]; | ||
weeks[0] = "월"; | ||
weeks[1] = "화"; | ||
weeks[2] = "수"; | ||
weeks[3] = "목"; | ||
weeks[4] = "금"; | ||
weeks[5] = "토"; | ||
weeks[6] = "일"; | ||
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System.out.println(weeks[3]); | ||
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} | ||
} |
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src/main/java/Practice/ggang9/Chapter3/BooleanPractice.java
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package Practice.ggang9.Chapter3; | ||
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public class BooleanPractice { | ||
public static void main(String[] args) { | ||
boolean isSuccess = true; | ||
boolean isTest = false; | ||
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int base = 180; | ||
int height = 185; | ||
boolean isTall = height > base; | ||
if (isTall) { | ||
System.out.println("키 큼"); | ||
} | ||
} | ||
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} |
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package Practice.ggang9.Chapter3; | ||
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public class CharPractice { | ||
public static void main(String[] args) { | ||
char a1 = 'a'; // 문자로 표현 | ||
char a2 = 97; // 아스키코드로 표현 | ||
char a3 = '\u0061'; // 유니코드로 표현 | ||
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System.out.println(a1); // a 출력 | ||
System.out.println(a2); // a 출력 | ||
System.out.println(a3); // a 출력 | ||
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} | ||
} |
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package Practice.ggang9.Chapter3; | ||
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import java.util.ArrayList; | ||
import java.util.Arrays; | ||
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public class FinalPractice { | ||
public static void main(String[] args) { | ||
String num = "123"; | ||
int n = Integer.parseInt(num); | ||
System.out.println(n); // 123 출력 | ||
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String num1 = String.valueOf(n); | ||
String num2 = Integer.toString(n); | ||
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final int n1 = 123; // final 로 설정하면 값을 바꿀수 없다. | ||
final ArrayList<String> a = new ArrayList<>(Arrays.asList("a", "b")); | ||
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} | ||
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} |
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package Practice.ggang9.Chapter3; | ||
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import java.util.ArrayList; | ||
import java.util.Arrays; | ||
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public class ListPractice { | ||
public static void main(String[] args) { | ||
ArrayList pitches = new ArrayList(); | ||
pitches.add("138"); | ||
pitches.add("129"); | ||
pitches.add("142"); | ||
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pitches.add(0, "133"); // 첫번째 위치에 133 삽입. | ||
pitches.add(1, "133"); | ||
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System.out.println(pitches.size()); | ||
System.out.println(pitches.remove("129")); | ||
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ArrayList<String> pitches1 = new ArrayList<>(); // 선호되는 방식 | ||
pitches1.add("138"); | ||
pitches1.add("129"); | ||
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String one = pitches1.get(0); // 형 변환이 필요없다. | ||
String two = pitches1.get(1); // 형 변환이 필요없다. | ||
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String[] data = {"138", "129", "142"}; // 이미 투구수 데이터 배열이 있다. | ||
ArrayList<String> pitches2 = new ArrayList<>(Arrays.asList(data)); | ||
System.out.println(pitches2); // [138, 129, 142] 출력 | ||
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} | ||
} |
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package Practice.ggang9.Chapter3; | ||
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import java.util.HashMap; | ||
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public class MapPractice { | ||
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public static void main(String[] args) { | ||
HashMap<String, String> map = new HashMap<>(); | ||
map.put("people", "사람"); | ||
map.put("baseball", "야구"); | ||
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System.out.println(map.get("people")); // "사람" 출력 | ||
System.out.println(map.containsKey("people")); // true 출력 | ||
System.out.println(map.remove("people")); // "사람" 출력 | ||
System.out.println(map.size()); | ||
System.out.println(map.keySet()); // [baseball, people] 출력 | ||
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} | ||
} |
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src/main/java/Practice/ggang9/Chapter3/NumberPractice.java
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package Practice.ggang9.Chapter3; | ||
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public class NumberPractice { | ||
public static void main(String[] args) { | ||
int age = 10; | ||
long countOfStar = 8764827384923849L; | ||
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float pi = 3.14F; | ||
double morePi = 3.14159265358979323846; | ||
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int a = 10; | ||
int b = 5; | ||
System.out.println(a+b); | ||
System.out.println(a-b); | ||
System.out.println(a*b); | ||
System.out.println(a/b); | ||
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int i = 0; | ||
int j = 10; | ||
i++; | ||
j--; | ||
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System.out.println(i); // 1 출력 | ||
System.out.println(j); // 9 출력 | ||
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} | ||
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} |
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package Practice.ggang9.Chapter3; | ||
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import java.util.Arrays; | ||
import java.util.HashSet; | ||
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public class SetPractice { | ||
public static void main(String[] args) { | ||
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HashSet<String> set = new HashSet<>(Arrays.asList("H", "e", "l", "l", "o")); | ||
System.out.println(set); // [e, H, l, o] 출력 | ||
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HashSet<Integer> s1 = new HashSet<>(Arrays.asList(1, 2, 3, 4, 5, 6)); | ||
HashSet<Integer> s2 = new HashSet<>(Arrays.asList(4, 5, 6, 7, 8, 9)); | ||
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HashSet<Integer> intersection = new HashSet<>(s1); // s1으로 intersection 생성 | ||
intersection.retainAll(s2); // 교집합 수행 | ||
System.out.println(intersection); // [4, 5, 6] 출력 | ||
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HashSet<Integer> union = new HashSet<>(s1); // s1으로 union 생성 | ||
union.addAll(s2); // 합집합 수행 | ||
System.out.println(union); // [1, 2, 3, 4, 5, 6, 7, 8, 9] 출력 | ||
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HashSet<Integer> substract = new HashSet<>(s1); // s1으로 substract 생성 | ||
substract.removeAll(s2); // 차집합 수행 | ||
System.out.println(substract); // [1, 2, 3] 출력 | ||
} | ||
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} |
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src/main/java/Practice/ggang9/Chapter3/StringBufferPractice.java
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package Practice.ggang9.Chapter3; | ||
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public class StringBufferPractice { | ||
public static void main(String[] args) { | ||
StringBuffer sb = new StringBuffer(); // StringBuffer 객체 sb 생성 | ||
sb.append("hello"); | ||
sb.append(" "); | ||
sb.append("jump to java"); | ||
String result = sb.toString(); | ||
System.out.println(result); // "hello jump to java" 출력 | ||
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StringBuffer sb1 = new StringBuffer(); | ||
sb1.append("jump to java"); | ||
sb1.insert(0, "hello "); | ||
System.out.println(sb1.toString()); | ||
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} | ||
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} |
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src/main/java/Practice/ggang9/Chapter3/StringPractice.java
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package Practice.ggang9.Chapter3; | ||
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public class StringPractice { | ||
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public static void main(String[] args) { | ||
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// String a = "Happy Java"; | ||
String b = "a"; | ||
String c = "123"; | ||
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boolean result = true; | ||
char a = 'A'; | ||
int i = 100000; | ||
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String a1 = "hello"; | ||
String b1 = "java"; | ||
String c1 = "hello"; | ||
System.out.println(a1.equals(b1)); // false 출력 | ||
System.out.println(a1.equals(c1)); // true 출력 | ||
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String a2 = "hello"; | ||
String b2 = new String("hello"); | ||
System.out.println(a2.equals(b2)); // true | ||
System.out.println(a2 == b2); // false | ||
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String a3 = "Hello Java"; | ||
System.out.println(a3.indexOf("Java")); // 6 출력 | ||
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String a4 = "Hello Java"; | ||
System.out.println(a4.charAt(6)); // "J" 출력 | ||
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String a5 = "Hello Java"; | ||
System.out.println(a5.replaceAll("Java", "World")); // Hello World 출력 | ||
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String a6 = "a:b:c:d"; | ||
String[] result1 = a6.split(":"); // result는 {"a", "b", "c", "d"} | ||
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} | ||
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} |
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src/main/java/Practice/ggang9/Chapter4/ForEachPractice.java
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package Practice.ggang9.Chapter4; | ||
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import java.util.ArrayList; | ||
import java.util.Arrays; | ||
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public class ForEachPractice { | ||
public static void main(String[] args) { | ||
String[] numbers = {"one", "two", "three"}; | ||
for(String number: numbers) { | ||
System.out.println(number); | ||
} | ||
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ArrayList<String> numbers2 = new ArrayList<>(Arrays.asList("one", "two", "three")); | ||
for (String number : numbers2) { | ||
System.out.println(number); | ||
} | ||
} | ||
} |
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package Practice.ggang9.Chapter4; | ||
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public class ForPractice { | ||
public static void main(String[] args) { | ||
String[] numbers = {"one", "two", "three"}; | ||
for(int i=0; i<numbers.length; i++) { | ||
System.out.println(numbers[i]); | ||
} | ||
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int[] marks = {90, 25, 67, 45, 80}; | ||
for(int i=0; i<marks.length; i++) { | ||
if (marks[i] >= 60) { | ||
System.out.println((i+1)+"번 학생은 합격입니다."); | ||
}else { | ||
System.out.println((i+1)+"번 학생은 불합격입니다."); | ||
} | ||
} | ||
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int[] marks1 = {90, 25, 67, 45, 80}; | ||
for(int i=0; i<marks1.length; i++) { | ||
if (marks1[i] < 60) { | ||
continue; // 조건문으로 돌아간다. | ||
} | ||
System.out.println((i+1)+"번 학생 축하합니다. 합격입니다."); | ||
} | ||
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} | ||
} |
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package Practice.ggang9.Chapter4; | ||
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import java.util.ArrayList; | ||
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public class IfPractice { | ||
public static void main(String[] args) { | ||
boolean money = true; | ||
if (money) { | ||
System.out.println("택시를 타고 가라"); | ||
}else { | ||
System.out.println("걸어가라"); | ||
} | ||
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int x = 3; | ||
int y = 2; | ||
System.out.println(x > y); | ||
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int money1 = 2000; | ||
if (money1 >= 3000) { | ||
System.out.println("택시를 타고 가라"); | ||
}else { | ||
System.out.println("걸어가라"); | ||
} | ||
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int money2 = 2000; | ||
boolean hasCard = true; | ||
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if (money2 >=3000 || hasCard) { | ||
System.out.println("택시를 타고 가라"); | ||
} else { | ||
System.out.println("걸어가라"); | ||
} | ||
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ArrayList<String> pocket = new ArrayList<String>(); | ||
pocket.add("paper"); | ||
pocket.add("handphone"); | ||
pocket.add("money"); | ||
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if (pocket.contains("money")) { | ||
System.out.println("택시를 타고 가라"); | ||
}else { | ||
System.out.println("걸어가라"); | ||
} | ||
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boolean hasCard2 = true; | ||
ArrayList<String> pocket2 = new ArrayList<String>(); | ||
pocket2.add("paper"); | ||
pocket2.add("handphone"); | ||
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if (pocket2.contains("money")) { | ||
System.out.println("택시를 타고 가라"); | ||
}else if(hasCard2) { | ||
System.out.println("택시를 타고 가라"); | ||
}else { | ||
System.out.println("걸어가라"); | ||
} | ||
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} | ||
} |
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