第二次作业

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;

import org.junit.Test;

public class Word {
    
    @Test
    public void testAnalyse() {
        String str = "Hello World My First Unit Test Test";
        analyse(str);
    }
    
    
    /**
     * 用于分析字符串单词频率，并输出
     * @param str
     */
    public void analyse(String str) {
        String[] array = str.split(" ");
        Map<String, Integer> map = new HashMap<String, Integer>();
        int n;    //临时记录单词出现频率
        for (String s : array) {
            if (map.get(s) == null) {
                map.put(s, 1);    //如果没出现过单词，就初始化1给这个单词
            } else {
                n = map.get(s);    //先保存
                map.remove(s);
                map.put(s, n+1);
            }
        }
        Iterator<Entry<String, Integer>> mapIt = map.entrySet().iterator();
        while (mapIt.hasNext()) {
            Entry<String, Integer> entry = mapIt.next();    //取出每一个实体
            System.out.println(entry.getKey() + ":" + entry.getValue());
        }
    }
}

其次是句子回转：

import org.junit.Test;


public class Sentence {
    
    @Test
    public void reverse() {
        String str = "aoteman";
        String newStr = "";
        for (int i = 0; i < str.length(); i++){
            newStr += str.charAt(str.length() - i - 1);
        }
        System.out.println(newStr);
//        System.out.println(new StringBuffer(str).reverse().toString()                                );
    }
}