CollectionsSample.java

import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Stack;

class App2 {

    public static void main(String[] args) {

    }

    private void arrayListSample() {
        List<String> names = new ArrayList<>();
        names.add("Magzhan");
        names.add("Askar");
        names.add("Rustem");

        int rustemPosition = names.indexOf("Rustem");
        System.out.println("Rustem position = " + rustemPosition);

        names.remove(2);
        names.add(0, "UUU");
        names.set(0, "ZZZ");

        System.out.println(names.get(1));
    }

    // Complexity O(1)
    private void hashMapSample() {
        Map<String, List<Car>> map = new HashMap<>();

        List<Car> magzhanCars = new ArrayList<>();
        magzhanCars.add(new Car("Mercedes"));
        magzhanCars.add(new Car("VW"));

        map.put("Magzhan", magzhanCars);
        map.put("Askar", new ArrayList<>());

        List<Car> originalCars = map.get("Magzhan");
        List<Car> modifiedCars = new ArrayList<>(originalCars);

        modifiedCars.remove(1);

        System.out.println("original size = " + originalCars.size());
        System.out.println("modified size = " + modifiedCars.size());
    }

    static class Car {

        private String name;

        Car(String name) {
            this.name = name;
        }

        public String getName() {
            return name;
        }
    }

    // Complexity O(n)
    private void linkedListSample() {
        LinkedList<String> list = new LinkedList<>();
        list.add("Magzhan");
        list.add("11");
        list.add("22");
        list.add("33");
        list.add("44");
        list.add("Askar");

        for (String str : list) {
            if (str.equals("22"))
                System.out.println("Found 22");
        }
    }

    private void queueSample() {
        Queue<Integer> queue = new PriorityQueue<>();
        queue.add(10);
        queue.add(20);
        queue.add(30);

        int firstElement = queue.poll();

        System.out.println(firstElement);
    }

    private void stackSample() {
        Stack<Integer> stack = new Stack<>();

        stack.push(1);
        stack.push(2);
        stack.push(3);

        int topElement = stack.peek();

        System.out.println(topElement);

        System.out.println(stack.size());
    }
}