实验二

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

public class Test {

    /**
     * 分析一个字符串中各个单词出现的频率
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String str="Hello World My First Unit Test";
        String[] items = str.split(" ");
        Map<String, Integer> map = new HashMap<String, Integer>();
        for (String s : items) {
            if (map.containsKey(s))
                map.put(s, map.get(s) + 1);
            else {
                map.put(s, 1);
            }
        }
        List<Entry<String, Integer>> list = new ArrayList<Entry<String, Integer>>();
        for (Entry<String, Integer> entry : map.entrySet()) {
            list.add(entry);
        }
        Collections.sort(list, new EntryComparator());

        for (Entry<String, Integer> obj : list) {
            System.out.println(obj.getKey() + "\t" + obj.getValue());
        }
    }
}

class EntryComparator implements Comparator<Entry<String, Integer>> {
    public int compare(Entry<String, Integer> o1, Entry<String, Integer> o2) {
        return o1.getValue() > o2.getValue() ? 0 : 1;
    }
}

import java.util.Scanner;
public class test {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入字符串：");
        String str = scanner.nextLine();
        String[] strs = str.split(" ");
        System.out.print("倒序后的字符串为:");
        for(int i = strs.length-1;i>=0;i--)
        {
            System.out.print(strs[i]+" ");
        }
        System.out.print("\n");
    }

}

实验二

原文：http://www.cnblogs.com/johnny-z/p/5327446.html