集合框架-工具类-Collections-折半最值

package cn.itcast.p2.toolclass.collections.demo;

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

import cn.itcast.p2.comparator.ComparatorByLength;

public class CollectionsDemo {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        /*
         * Collections：是集合框架的工具类。
         * 里面的方法都是静态的。
         */
//        demo_1();
        demo_2();
        
    }
    
    private static void demo_2() {
        // TODO Auto-generated method stub
        List<String> list = new ArrayList<String>();
        
        list.add("abcde");
        list.add("cba");
        list.add("aa");
        list.add("zzz");
        list.add("cba");
        list.add("nbaa");
        //折半要先排序
        Collections.sort(list);
        System.out.println(list);
        
        int index = Collections.binarySearch(list, "aaa");
        
        System.out.println("index="+index);
        
        //获取最大值。
//        String max = Collections.max(list);//max=zzz
        String max = Collections.max(list,new ComparatorByLength());
        System.out.println("max="+max);
    }

package cn.itcast.p2.comparator;

import java.util.Comparator;

public class ComparatorByLength implements Comparator<String> {

    @Override
    public int compare(String o1, String o2) {
        // TODO Auto-generated method stub
        int temp = o1.length()-o2.length();
        
        return temp==0?o1.compareTo(o2):temp;
    }

}