자료 구조 : List

java.lang.Object
    java.util.AbstractCollection<E>
        java.util.AbstractList<E>
            java.util.ArrayList<E>

Serializable, Cloneable, Iterable<E>, Collection<E>, List<E>, RandomAccess

public class ListSample{
    public static void main(String[] args){
        ListSample sample = new ListSample();
	      sample.checkArrayList1();
    }

    public void checkArrayList1(){
        ArrayList list1 = new ArrayList();
				list1.add(new Object());
        list1.add("ArrayListSample");
        list1.add(new Double(1));
    }
}

ArrayList<String> list1 = new ArrayList<>();

public void checkArrayList1() {
        ArrayList<String> list1 = new ArrayList<>();
        list1.add(new Object());
        list1.add("ArrayListSample");
        list1.add(new Double(9));
    }

ArrayList<String> list2 = new ArrayList<String>(100); // 이렇게 크기 지정

List2 = 0
List2 = A
List2 = A1
List2 = B
List2 = C
List2 = D
List2 = E

List2 A
List2 OOops

list2 = list

for(타입이름 임시변수명 : 반복대상객체){

}

public void checkArrayList6(){
    ArrayList<String> list = new ArrayList<>();
    list.add("A");
    String[] strList = list.toArray(new String[0]);
    System.out.println(strList[0]);
}

public void checkArrayList7(){
    ArrayList<String> list = new ArrayList<>();
    list.add("A");
    list.add("B");
    list.add("C");
    String[] tempArray = new String[3];
    String[] strList = list.toArray(tempArray);
    for (String temp : strList) {
        System.out.println(temp);
     }
}

A
B
C

String[] tempArray = new String[5];

A
B
C
null
null

String[] tempArray = new String[2];

null
null

public void checkArrayList8(){
    ArrayList<String> list = new ArrayList<>();
    list.add("A");
    list.add("B");
    list.add("C");
    list.add("A");
    System.out.println(list.remove("A"));

    for (int loop = 0; loop < list.size(); loop++) {
        System.out.println("list.get(" + loop + ")=" + list.get(loop));
    }
}

true
list.get(0)=B
list.get(1)=C
list.get(2)=A

public void checkArrayList8(){
    ArrayList<String> list = new ArrayList<>();
    list.add("A");
    list.add("B");
    list.add("C");
    list.add("A");
    ArrayList<String> temp = new ArrayList<>();
    temp.add("A");
    list.removeAll(temp);

    for (int loop = 0; loop < list.size(); loop++) {
        System.out.println("list.get(" + loop + ")=" + list.get(loop));
    }
}

list.get(0)=B
list.get(1)=C

public void setList(){
    ArrayList<String> list = new ArrayList<>();
    list.add("X");
    list.add("B");
    list.add("C");

    list.set(1, "A"); // set(int index, E element)
    list.set(2, "A"); // set(int index, E element)
    for (String s : list) {
        System.out.println(s);
    }
}

X
A
A

public class ListSample {
    public static void main(String[] args){
        ArrayList<Integer> arr = new ArrayList<Integer>(9);
        arr.add(2);
        arr.add(4);
        arr.add(5);
        arr.add(6);
        arr.add(11);


        arr.trimToSize();

        System.out.println("The List elements are:");


        for (Integer number : arr) {
            System.out.println("Number = " + number);
        }
    }
}

The List elements are:
Number = 2
Number = 4
Number = 5
Number = 6
Number = 11

java.lang.Object
    java.util.AbstractCollection<E>
        java.util.AbstractList<E>
            java.util.Vector<E>
                java.util.Stack<E>

import java.util.*;
public class Main{
    static int[] stack;
    static int size=0 ;

    public void push(int data){
        stack[size] = data;
        size +=1;
    }

    public int pop(){
        if(size == 0) return -1;
        else{
          size--;
          return stack[size];
        }
    }

    public int top(){
        if(size == 0) return -1;
        return  stack[size -1];
    }

    public int size(){
        return size;
    }

    public int empty(){
        if(size == 0) return 1; //비어있다
        else return 0;// 비어있지않다.
    }

    public static void main(String[] args){
        Main T = new Main();
        Scanner in = new Scanner(System.in); //
        StringBuilder sb = new StringBuilder(); //문자 입력

        int n = in.nextInt(); // 데이터 입력
        stack = new int[n]; //스택공간

        for(int i = 0 ; i < n ; i++){ //Test : 14
            String s = in.next(); // push, pop, top, size,empty

            switch(s){
                case "push":
                    T.push(in.nextInt()); //data : 1 ,2 ...etc
                    break;

                case "pop":
                    sb.append(T.pop()).append('\n');
                    break;

                case "size":
                    sb.append(T.size()).append('\n');
                    break;
                case "empty":
                    sb.append(T.empty()).append('\n');
                    break;
                case "top":
                    sb.append(T.top()).append('\n');
                    break;
            }

        }
        System.out.println(sb);
    }

}