java排序接口

算法我不懂，所以直接用现成的东西比较容易。

java api里面实现的排序接口有Collection.sort和TreeMap，sort原理是归并排序，treeMap是红黑树排序。

package com.study.collection;


import java.util.*;

/**
 * Created by DELL on 2016-5-12.
 */
public class Sort {

    /**
     * treeMap排序
     */
    public static void treeMapTest(){
        /**
         * treeMap排序,排序原理是红黑树排序
         * 如果没有指定排序器，默认按照key的string的升序排列，
         * string会先转换成char，如果是中文对转换成中文的unicode编码，把编码的升序排列
         * 建议最好指定排序器，否则有中文时会有问题
         */
        Map<String,String> treeMap = new TreeMap<String,String>(new CollatorComparator());
        treeMap.put("zbc","zbc");
        treeMap.put("你好","你好");
        treeMap.put("111","111");
        treeMap.put("北京","北京");
        treeMap.put("厦门","厦门");
        treeMap.put("碑海","碑海");
        System.out.println(treeMap);
    }

    /**
     *Collection排序，排序原理归并排序
     */
    public static void ListStortTest(){
        List<Object> list = new ArrayList<Object>();
        list.add("123");
        list.add("132");
        list.add("abc");
        list.add("acc");
        list.add("碑海");
        list.add("厦门");
        list.add("北京");
        //排序时如果list的元素没有实现Comparable接口，则必须传入排序器
        Collections.sort(list,new CollatorComparator());
        System.out.println(list);
        Collections.reverse(list);
        System.out.println("逆序"+list);
    }

    /**
     * 实现Comparable接口排序
     *Collection排序，排序原理归并排序
     */
    public static void listSortBeanTest(){
        List<SortBean> list = new ArrayList<SortBean>();
        list.add(new SortBean("123"));
        list.add(new SortBean("132"));
        list.add(new SortBean("abc"));
        list.add(new SortBean("acc"));
        list.add(new SortBean("碑海"));
        list.add(new SortBean("厦门"));
        list.add(new SortBean("北京"));
        //排序元素list的元素没有实现Comparable接口,如果传入排序器，则bean的Comparable接口无效
        Collections.sort(list/*,new SortBeanComparator()*/);
        System.out.println(list);
    }
    public static void main(String[] args){
        //Sort.treeMapTest();
       // Sort.ListStortTest();
        Sort.listSortBeanTest();
    }
}

package com.study.collection;

import java.text.CollationKey;
import java.text.Collator;
import java.util.Comparator;
import java.util.Locale;

/**
 * 排序器
 */
public class CollatorComparator implements Comparator<Object> {
        //本地化语言
        Collator collator = Collator.getInstance(Locale.SIMPLIFIED_CHINESE);

    /**
     * 重写这个方法，使用简体中文排序
     * @param el1
     * @param el2
     * @return
     */
        public int compare(Object el1,Object el2){
            CollationKey key1 = collator.getCollationKey(el1.toString());
            CollationKey key2 = collator.getCollationKey(el2.toString());
            return key1.compareTo(key2);
        }
    }

package com.study.collection;

import java.text.Collator;
import java.util.Comparator;
import java.util.Locale;

/**
 * Created by DELL on 2016-5-12.
 */
public class SortBean implements Comparable<SortBean>{
    private String content;
    Collator collator = Collator.getInstance(Locale.SIMPLIFIED_CHINESE);
    public SortBean(String content){
        this.content = content;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }



    @Override
    public int compareTo(SortBean o) {
        return collator.compare(this.getContent(),o.getContent());
    }



    @Override
    public String toString() {
        return this.content;
    }
}