java list集合使用Collections中的sort方法进行排序（Comparator），超实用

在java中有没有遇到对list集合进行排序，其实很简单的，需要集合类Collections中sort方法

public static <T> void sort(List<T> list, Comparator<? super T> c) {
        Object[] a = list.toArray();
        Arrays.sort(a, (Comparator)c);
        ListIterator i = list.listIterator();
        for (int j=0; j<a.length; j++) {
            i.next();
            i.set(a[j]);
        }
    }

使用方法及代码实现：

package collections.sort;

import java.util.Date;


public class Book {
	private Long id;
	private Date time;
	private String name;

	public Book(Long id, Date time, String name) {
		super();
		this.id = id;
		this.time = time;
		this.name = name;
	}
	public Long getId() {
		return id;
	}
	public void setId(Long id) {
		this.id = id;
	}
	public Date getTime() {
		return time;
	}
	public void setTime(Date time) {
		this.time = time;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}

}

package collections.sort;

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

public class TestSort {
	public static void main(String[] args) {
		List<Book> books = new ArrayList<>();
		books.add(new Book(5l, subDate(0), "zjq5"));
		books.add(new Book(2l, subDate(3), "zjq2"));
		books.add(new Book(3l, subDate(2), "zjq3"));
		books.add(new Book(1l, subDate(4), "zjq1"));
		books.add(new Book(4l, subDate(1), "zjq4"));
		Collections.sort(books, new Comparator<Book>() {

			@Override
			public int compare(Book o1, Book o2) {
				//o1和o2反过来决定升序和降序
//				return o1.getId().compareTo(o2.getId());升序
//				return o2.getId().compareTo(o1.getId());降序
//				return o1.getName().compareTo(o2.getName());
//				return o2.getName().compareTo(o1.getName());
//				return o1.getTime().compareTo(o2.getTime());
				return o2.getTime().compareTo(o1.getTime());
			}

		});
		for (Book book : books) {
			System.out.println(book.getId());
		}
	}

	//日期减一天 加一天
	public static Date subDate(int sum){
		return new Date(new Date().getTime()-sum*24*60*60*1000);
	}
}