/*** 商品po类*/
public class Items implements java.lang.Comparable<Items> {private String title;private int hits;private Date pubTime;public Items() {}public Items(String title, int hits, Date pubTime) {super();this.title = title;this.hits = hits;this.pubTime = pubTime;}public String getTitle() {return title;}public void setTitle(String title) {this.title = title;}public int getHits() {return hits;}public void setHits(int hits) {this.hits = hits;}public Date getPubTime() {return pubTime;}public void setPubTime(Date pubTime) {this.pubTime = pubTime;}//时间降序 点击量升序 标题降序
    @Overridepublic int compareTo(Items o) {int result = 0;//按照生产时间降序result = - this.pubTime.compareTo(o.pubTime);if(0==result){//如果生产时间相同 就按照销售量升序排列result = this.hits-o.hits;if(0==result){//如果销售量相同 按照名字降序排列result = - this.title.compareTo(o.title);}}return result;}@Overridepublic String toString() {StringBuilder sb = new StringBuilder();sb.append("商品名称").append(this.title);sb.append("销售量").append(this.hits);sb.append("生产时间").append(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(this.pubTime)).append("\n");return sb.toString();}}

    //时间降序， 销售量升序， 标题降序
public static void main(String[] args) {List<Items> item = new ArrayList<Items>();item.add(new Items("abcitems",30,new Date(System.currentTimeMillis()-1000*60*60)));item.add(new Items("abcfgitems",30,new Date(System.currentTimeMillis()-1000*60*50)));item.add(new Items("abcditems",100,new Date()));item.add(new Items("abefNews",50,new Date(System.currentTimeMillis()-1000*60*60)));System.out.println("----------排序前----------");System.out.println(item);System.out.println("----------排序后----------");Collections.sort(item);System.out.println(item);
}

/*** 定义业务的比较规则，我需要按照字符串的长度进行比较(在实际的场景中，可以根据业务的需求，灵活的改变比较规则，实现排序)*/
public class CompareString implements java.util.Comparator<String> {@Overridepublic int compare(String o1, String o2) {int len1 = o1.length();int len2 = o2.length();return -(len1-len2);//需要按照降序排列
    }
}

    public static void main(String[] args) {List<String>  list = new ArrayList<String>();list.add("abc");list.add("abcd");list.add("ab");list.add("abd");Collections.sort(list,new CompareString());System.out.println(list);//[abcd, abc, abd, ab]}

/*** 商品po类*/
public class Products {private String title;private int price;public Products() {}public Products(String title, int price) {super();this.title = title;this.price = price;}public String getTitle() {return title;}public void setTitle(String title) {this.title = title;}public int getPrice() {return price;}public void setPrice(int price) {this.price = price;}@Overridepublic String toString() {return "title=" + title+",price=" + price  +"\n";}
}

/*** 按照价格的降序排列*/public class ProductCompare implements java.util.Comparator<Products> {@Overridepublic int compare(Products o1, Products o2) {return -( o1.getPrice()-o2.getPrice()>0?1: (o1.getPrice()==o2.getPrice()?0:-1));}}

public static void main(String[] args) {List<Products> product = new ArrayList<Products>();product.add(new Products("a",120));product.add(new Products("b",143432));product.add(new Products("c",1892));product.add(new Products("d",11092));Collections.sort(product,new ProductCompare());System.out.println(product);结果:[title=b,price=143432title=d,price=11092title=c,price=1892title=a,price=120]}