JAVA Collection - List

List

List<Integer> integerList = new ArrayList<>();
integerList.add(1);
integerList.add(5);
integerList.add(4);
integerList.add(11);
integerList.add(10);

System.out.println(integerList);

[1, 5, 4, 11, 10]

---

오름차순 정리

List<Integer> integerList = new ArrayList<>();
integerList.add(1);
integerList.add(5);
integerList.add(4);
integerList.add(11);
integerList.add(10);

System.out.println(integerList);

Collections.sort(integerLsit);
//이 integerList 리스트 안에 담긴 걸 정렬할거야!
아무 설정을 안해주면 기본적으로 오름차순 정렬을 해준다.

System.out.println(integerList);
System.out.println(integerList.size);
//.size 는 .lengh 처럼 element의 개수를 의미한다.

[1, 4, 5, 10, 11]
5

---

이미 넣은 것을 지울 때

List<Integer> integerList = new ArrayList<>();
integerList.add(1);
integerList.add(5);
integerList.add(4);
integerList.add(11);
integerList.add(10);

System.out.println(integerList);

Collections.sort(integerLsit);

System.out.println(integerList);
System.out.println(integerList.size);

integerList.removw( index: 4);
System.out.println(integerList);

[1, 4, 5, 10]

---

for문을 활용해보기

List<Integer> integerList = new ArrayList<>();
integerList.add(1);
integerList.add(5);
integerList.add(4);
integerList.add(11);
integerList.add(10);

System.out.println(integerList);

Collections.sort(integerLsit);

System.out.println(integerList);
System.out.println(integerList.size);

integerList.removw( index: 4);
System.out.println(integerList);

for(int i=o; i<integerList.size(); i++) {
	System.out.println(integerList.get(i));
}

1
4
5
10

for문 반복문 더 쉽게 쓰기
이렇게 쓰면 알아서 하나씩 꺼내서 current에 할당해준다.

List<Integer> integerList = new ArrayList<>();
integerList.add(1);
integerList.add(5);
integerList.add(4);
integerList.add(11);
integerList.add(10);

System.out.println(integerList);

Collections.sort(integerLsit);

System.out.println(integerList);
System.out.println(integerList.size);

integerList.removw( index: 4);
System.out.println(integerList);

//for(int i=o; i<integerList.size(); i++) {
//	System.out.println(integerList.get(i));
//}

for(int current: intergerList){
	System.out.println(current);
}

1
4
5
10