题目一： 写一个Java程序，用于分析一个字符串中各个单词出现的频率，并将单词和它出现的频率输出显示。

Demo类：

import java.util.HashMap;

import java.util.Iterator;

Map<String, Integer> wordsMap = new HashMap<String, Integer>();
for (String word : wordsArray) {

if (wordsMap.containsKey(word)) {
wordsMap.put(word, wordsMap.get(word) + 1);
} else {
wordsMap.put(word, 1);
}
}

Set<String> setKey = wordsMap.keySet();
Iterator<String> itKey = setKey.iterator();
while (itKey.hasNext()) {
String word = itKey.next().toString();
int count = wordsMap.get(word);

System.out.println("单词 " + word + " 出现" + count + "次");

}
}

}

DemoTest：

import static org.junit.Assert.*;
import org.junit.Test;

public class DemoTest {

@Test
public void testCountWord() {
Demo demo = new Demo();
demo.countWord("Hello World My First Unit Test");
}

}