package com.company;

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

/**
 * Created by ttc on 2018/1/8.
 */
public class Dictionary {
    public static void main(String[] args) {
        Map<String,String> dic = new HashMap<String, String>();

        //向字典增加词汇和释义
        dic.put("dog","狗");
        dic.put("cat","猫");
        dic.put("apple","苹果");
        dic.put("tiger","老虎");
        dic.put("lion","狮子");
        
        Scanner scanner = new Scanner(System.in);

        while (true)
        {
            System.out.println("请输入要查询的单词,no退出");
            String word = scanner.next();

            if(word.equals("no"))
            {
                break;
            }
            //看字典的key中是否包含该单词
            if(dic.containsKey(word))
            {
                System.out.println(dic.get(word));
            }
            else
            {
                System.out.println("该单词还没有被收录");
            }
        }

        System.out.println("欢迎使用");



    }
}

查单词

package com.company;

import java.util.HashMap;
import java.util.Map;

/**
 * Created by ttc on 2018/1/8.
 */
//一篇英文文章，单词间用空格分割，统计出现了哪些单词，以及每个单词出现的次数。
public class wordCount {
    public static void main(String[] args) {
        //问题结果
//        this----------2
//        is------------2
//        a-------------2
//        book----------1
//        that----------1
//        desk----------1
        String article = "this this is a book that is a desk";//问题的开始，问题的输入
        String[] words = article.split(" ");
        //Map<String,Integer> key保存的是单词，value保存的是该单词出现的次数
        Map<String,Integer> map = new HashMap<>();

        //this----2
        //考察单词数组中的每一个单词,
        for(int i = 0; i < words.length; i++)
        {
            //考察每一个单词，
            if(map.containsKey(words[i]))//如果map的key中存在该单词,将该单词出现的次数加1
            {
               int count = map.get(words[i]);
               count++;
               map.put(words[i],count);
            }
            else//如果map的key中不存在该单词，将该单词添加到map中
            {
                map.put(words[i],1);
            }
        }

        for(String word : map.keySet())
        {
            System.out.println(word+"--------"+map.get(word));
        }

    }

}

考试排名

public static void main(String[] args) {
    //java考试排名信息
    Map<Integer,String> map = new HashMap<Integer,String>();//创建一个空的map
    //往map中添加元素
    map.put(1,"张三");
    map.put(2,"lisi");
    map.put(3,"wangwu");

    System.out.println("排第5的是谁");
    String name = map.get(5);//查找--在map集合中查找key对应的值
    System.out.println(name);

    //map.containsKey()询问map中是否包含某个key，返回值boolean
    System.out.println(map.containsKey(3));
    System.out.println(map.containsKey(33));


}