Input 처리

import java.io.*;

public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));  
		StringTokenizer st = new StringTokenizer(br.readLine());
		
		char[] inputArray = st.nextToken.toCharArray();
	}
}

Array

Integer arr[] = new int[10];
Integer arr[] = {1, 2, 3};

import java.util.*;

Arrays.sort(arr);
Arrays.sort(arr, Collections.reverseOrder())

List<Integer> list = new ArrayList<>();

System.out.println(arr.length);
System.out.println(listsize());

list.add(1);  //{1}
list.add(0, 3);  //{3,1}
list.set(0, 5);  //{5,1}
list.remove(0); //{1}

list.contains(1);
list.indexOf(3);

for (int num: list) {
	System.out.println(num);
}

//정렬
Collections.sort(list);
Collections.max(list);

List<List<Integer>> matrix = new ArrayList<>();
matrix.add(Arrays.asList(1, 2));
matrix.add(Arrays.asList(3, 4));
Collections.sort(list, (o1, o2) -> o1.get(1) - o2.get(1));
Collections.sort(list, new Comparator<List<Integer>() {
	@Override
	public int compare(List<Integer> o1, List<Integer> o2) {
		return o1.get(1) - o2.get(1);
	}
});

List<Integer> intList = Arrays.asList(arr);

String

String str = "12345 6789";

str.split(" ");
str.substring(0, 5);

char[] charArray = str.toCharArray();

Queue

import java.util.*;

Queue<Integer> queue = new LinkedList<>();
//추가
queue.add(1);  //실패시 exception
queue.offer(2);  //실패시 false
//삭제
queue.remove(2);
Integer value = queue.poll(1);
//0번째 인덱스 반환
queue.element();
queue.peek();

Stack

import java.util.*;

Stack<Integer> stack = new Stack<>();
//추가
stack.push(1);
//삭제
stack.pop(1);

HashMap

HashMap<Integer, Integer> map = new HashMap<>();
//추가
map.put(1, 1);
//읽기
map.get(1);
map.getOrDefault(1);

최대 최소

Math.max(1, 2);
Math.min(1, 2);