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SortJava.java
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172 lines (143 loc) · 5.5 KB
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package Sort;
import java.util.*;
public class SortJava {
public static void main(String[] args) {
SortJava sj = new SortJava();
// 원시 타입 정렬
System.out.println("==primitiveTypeSort==");
sj.primitiveTypeSort();
// 컬렉션 정렬
System.out.println("\n==collectionSort==");
sj.collectionSort();
// 커스텀 정렬
System.out.println("\n==customSort==");
sj.customSort();
// 오버라이드 커스텀 정렬
System.out.println("\n==overrideCustomSort==");
sj.overrideCustomSort();
// 두 조건 커스텀 정렬 오버라이드
System.out.println("\n==customSortTwoConditionOverride==");
sj.customSortTwoConditionOverride();
// 두 조건 커스텀 정렬
System.out.println("\n==customSortTwoCondition==");
sj.customSortTwoCondition();
}
// 원시타입 정렬
private void primitiveTypeSort() {
int[] nums = {5, 2, 8, 1, 3};
// 오름차순 정렬
Arrays.sort(nums);
System.out.println(Arrays.toString(nums)); // [1, 2, 3, 5, 8]
// 내림차순 정렬 (박싱 필요)
Integer[] boxed = Arrays.stream(nums).boxed().toArray(Integer[]::new);
Arrays.sort(boxed, (a, b) -> b - a);
System.out.println(Arrays.toString(boxed)); // [8, 5, 3, 2, 1]
}
// 컬랙션 정렬
private void collectionSort() {
List<String> list = new ArrayList<>(Arrays.asList("banana", "apple", "cherry"));
// 오름차순 정렬
Collections.sort(list);
System.out.println(list); // [apple, banana, cherry]
// 내림차순 정렬
Collections.sort(list, Collections.reverseOrder());
System.out.println(list); // [cherry, banana, apple]
// Stream + Comparator 활용 (길이 기준 오름차순)
List<String> sortedByLength = list.stream()
.sorted(Comparator.comparingInt(String::length))
.toList();
System.out.println(sortedByLength);
}
private void customSort() {
List<Person> people = List.of(
new Person("Alice", 30),
new Person("Bob", 25),
new Person("Charlie", 28)
);
// 나이 오름차순
List<Person> byAge = new ArrayList<>(people);
byAge.sort(Comparator.comparingInt(p -> p.age));
System.out.println(byAge); // [Bob(25), Charlie(28), Alice(30)]
// 이름 내림차순
List<Person> byNameDesc = new ArrayList<>(people);
byNameDesc.sort(Comparator.comparing((Person p) -> p.name).reversed());
System.out.println(byNameDesc); // [Charlie(28), Bob(25), Alice(30)]
}
private void overrideCustomSort() {
List<Person> people = List.of(
new Person("Alice", 30),
new Person("Bob", 25),
new Person("Charlie", 28)
);
// 나이 오름차순
List<Person> byAge = new ArrayList<>(people);
byAge.sort(new Comparator<Person>() {
@Override
public int compare(Person o1, Person o2) {
// Integer.compare로 안전하게 비교
return Integer.compare(o1.age, o2.age);
}
});
System.out.println(byAge); // [Bob(25), Charlie(28), Alice(30)]
// 이름 내림차순
List<Person> byNameDesc = new ArrayList<>(people);
byNameDesc.sort(new Comparator<Person>() {
@Override
public int compare(Person o1, Person o2) {
// o2.name.compareTo(o1.name) ⇒ 내림차순
return o2.name.compareTo(o1.name);
}
});
System.out.println(byNameDesc); // [Charlie(28), Bob(25), Alice(30)]
}
private void customSortTwoConditionOverride() {
List<Person> people = new ArrayList<>(Arrays.asList(
new Person("Alice", 30),
new Person("Charlie", 28),
new Person("Bob", 25),
new Person("Charlie", 22)
));
Collections.sort(people, new Comparator<Person>() {
@Override
public int compare(Person o1, Person o2) {
// 1) 이름 내림차순
int nameCmp = o2.getName().compareTo(o1.getName());
if (nameCmp != 0) {
return nameCmp;
}
// 2) 이름이 같으면 나이 오름차순
return Integer.compare(o1.getAge(), o2.getAge());
}
});
System.out.println(people);
}
private void customSortTwoCondition() {
List<Person> people = Arrays.asList(
new Person("Alice", 30),
new Person("Charlie", 28),
new Person("Bob", 25),
new Person("Charlie", 22)
);
// 이름 내림차순, 나이 오름차순
people.sort(
Comparator
.comparing(Person::getName, Comparator.reverseOrder())
.thenComparingInt(Person::getAge)
);
System.out.println(people);
}
public static class Person {
String name;
int age;
Person(String name, int age) {
this.name = name;
this.age = age;
}
public String getName() { return name; }
public int getAge() { return age; }
@Override
public String toString() {
return name + "(" + age + ")";
}
}
}