int[] array = { 3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5, 8 };
Arrays.sort(array);

Integer[] array = { 3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5, 8 };
Arrays.sort(array, Collections.reverseOrder());

ArrayList<Integer> al = new ArrayList<>();
al.add(2);
al.add(7);
al.add(1);
al.add(8);
al.add(2);
al.add(8);
Collections.sort(al);

ArrayList<Integer> al = new ArrayList<>();
al.add(2);
al.add(7);
al.add(1);
al.add(8);
al.add(2);
al.add(8);
Collections.sort(al, Collections.reverseOrder());

import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;

public class Main {

	public static void main(String[] args) {

		List<Item> itemList = new ArrayList<>();
		itemList.add(new Item(4, "Book", 1000));
		itemList.add(new Item(2, "Bag", 3000));
		itemList.add(new Item(3, "Calendar", 2000));
		itemList.add(new Item(1, "pen", 200));

		//id ascending sort
		itemList.sort(Comparator.comparing(Item::getId));

		//id descending sort
		itemList.sort(Comparator.comparing(Item::getId).reversed());

		//kind ascending sort
		itemList.sort(Comparator.comparing(Item::getKind));

		//kind descending sort
		itemList.sort(Comparator.comparing(Item::getKind).reversed());

	}
}

class Item {
	int id;
	String kind;
	int price;

	Item(int id, String kind, int price) {

		this.id = id;
		this.kind = kind;
		this.price = price;
	}

	public int getId() {
		return id;
	}

	public String getKind() {
		return kind;
	}

}

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