Collections练习

Love The Way You Lie 2022-05-19 10:47 165阅读 0赞

import java.util.*;
    
    class CollectionsTest 
    {
    	public static void main(String[] args) 
    	{
    		//mySort();
    		//myMax();
    		myBinarySearch();
    	}
    
    	public static void mySort()
    	{
    		List<String> list = new ArrayList<String>();
    
    		list.add("abcd");
    		list.add("aaa");
    		list.add("zz");
    		list.add("kkkkk");
    		list.add("qq");
    		list.add("z");
    		
    		sop(list);
    		// Collections.sort(list);
    		Collections.sort(list, new StrLenCompartor());
    		//Collections.swap(list,1,2);
    		sop(list);
    	}
    
    	public static void myMax()
    	{
    		List<String> list = new ArrayList<String>();
    
    		list.add("abcd");
    		list.add("aaa");
    		list.add("zz");
    		list.add("kkkkk");
    		list.add("qq");
    		list.add("z");
    		
    		Collections.sort(list);
    		sop(list);
    		String max = Collections.max(list/*, new StrLenCompartor()*/);
    		sop("max:" + max);
    	}
    
    	public static void myBinarySearch()
    	{
    		List<String> list = new ArrayList<String>();
    
    		list.add("abcd");
    		list.add("aaa");
    		list.add("zz");
    		list.add("kkkkk");
    		list.add("qq");
    		list.add("z"); 
    		Collections.sort(list);
    		//Collections.sort(list, new StrLenCompartor());
    
    		sop(list);
    
    		int index = Collections.binarySearch(list, "aaa");
    		//int index = halfSearch(list, "aaaa");
    		//int index = halfSearch2(list, "aaaa", new StrLenCompartor());
    		sop("index:" + index);
    	}
    
    	public static int halfSearch(List<String> list, String key)
    	{
    		int max, min, mid;
    		max = list.size() - 1;
    		min = 0;
    		
    		while(min <= max)
    		{
    			mid = (max + min) >> 1;
    			
    			String str = list.get(mid);
    			int num = str.compareTo(key);
    
    			if(num > 0)
    				max = mid -1;
    			else if(num < 0)
    				min = mid + 1;
    			else
    				return mid;
    		}
    		return -min - 1;
    	}
    
    	public static int halfSearch2(List<String> list, String key, Comparator<String> cmp)
    	{
    		int max, min, mid;
    		max = list.size() - 1;
    		min = 0;
    		
    		while(min <= max)
    		{
    			mid = (max + min) >> 1;
    			
    			String str = list.get(mid);
    			int num = cmp.compare(str, key);
    
    			if(num > 0)
    				max = mid -1;
    			else if(num < 0)
    				min = mid + 1;
    			else
    				return mid;
    		}
    		return -min - 1;
    	}
    
    
    	public static void sop(Object obj)
    	{
    		System.out.println(obj);
    	}
    }
    
    class StrLenCompartor implements Comparator<String>
    {
    	public int compare(String s1, String s2)
    	{
    		if(s1.length() > s2.length())
    			return 1;
    		if(s1.length()<s2.length())
    			return -1;
    		return s1.compareTo(s2);
    	}
    }