面试题目

用map去记录每个字符出现的个数，最后并对map里面value存贮的字母出现的次数，返回排序好的 Map.Entry<String, Integer>[]数组。此代码没有考虑效率。欢迎拍砖

public class WordCount {
	public static void main(String[] args) {
		String words = "hello wolrd wlllkdsfhksadfls?sdfls sdf.pqyutgvAAAxzsdfs lsdfj,ljsfd  ajfdsak" +" sfksjdfisfsdkfj lsdfjsidf jsafdalsjfs sfskdfjs";

		words = words.replaceAll("[^a-zA-Z]", "");
		StringCounter strCounter = new StringCounter();
		String strTem;
		for(int i = 0; i < words.length(); i++) {
			strTem = String.valueOf(words.charAt(i));
			strCounter.count(strTem);
		}

		//getSortedHashtableByValue(strCounter);
                  //遍历排序好的Map.Entry，从大到小
		for(Map.Entry<String, Integer> entry : getSorted(strCounter)) {
			System.out.println(entry.getKey() + "------------" + entry.getValue());
		}
	}
	
	//嵌套类（记录每个字母出现的次数）
	static class StringCounter extends HashMap<String,Integer> {
		public void count(String str) {
			Integer num = get(str);
			put(str,num == null ? 1 : num + 1);	
		}
	}
	
	//返回排序好的数组
	static Map.Entry<String, Integer>[] getSorted(Map<String,Integer> m) {
		Set set = m.entrySet();
		Map.Entry<String, Integer>[] entries = 
			(Map.Entry<String, Integer>[]) set.toArray(new Map.Entry[set.size()]);
		//Comparator 
		Arrays.sort(entries, new Comparator<Map.Entry<String, Integer>>() {
			@Override
			public int compare(Entry<String, Integer> entry1, 
					Entry<String, Integer> entry2) {
				Integer in1 = entry1.getValue();
				Integer in2 = entry2.getValue();
				return in2.compareTo(in1);
			}
		} );
		return  entries;
	}
}

public static void main(String[] args) throws InterruptedException {
		String str = "1232aaaaazzzzzccAAAAAAAAAAAAAAacccafsfrerwerzzbb,ccdcc ";
		int[] words = new int[26];
		for (int i = 0; i < str.length(); i++) {
			char c = str.charAt(i);
			if (c >= 'a' && c <= 'z') {
				int idx = c - 'a';
				words[idx] = words[idx] + 1;
			} else if (c >= 'A' && c <= 'Z') {
				int idx = c - 'A';
				words[idx] = words[idx] + 1;
			}
		}
		int maxIdx = 0,arrMax = words[0];
		for (int i = 1; i < words.length; i++) {
			if (words[i] > arrMax) {
				arrMax = words[i];
				maxIdx = i;
			}
		}
		System.out.println("出现次数最多的字母是：" + (char)('A' + maxIdx) + " 出现次数是：" + arrMax);
	}

看了你的代码,我感觉很糟糕,因為你把问题复杂化了!!!
他并没有说用什么语言来开发,我写了2种方式给你,不能说最好,但是精简
JS版本
<script>
var token = {};
var str = "a nn   dd  sdd sasd2312";
for(var i = 0;i < str.length;i++){
var s = str.charAt(i);
if(token[s] >= 1){
token[s]++;
}
else{
token[s] = 1;
}
}
var result=  "" ;
for(var p in token){
result += (p+" = "+token[p])+"\n"
}
alert(result)
//TODO 排序获取最大的一个,整个代码不超过30行
  </script>

JAVA版本

import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;

public class Test3 {
/**
* 计算个数
* @param str
* @return
*/
private Map<Character ,Integer> getToken(String str){
Map<Character ,Integer> token = new LinkedHashMap<Character ,Integer>();
for(int  i = 0;i < str.length();i++){
if(token.get(str.charAt(i)) != null){
token.put(str.charAt(i), token.get(str.charAt(i))+1);
}
else{
token.put(str.charAt(i), 1);
}
}
return token;
}

public static void main(String[] args) {
Test3 t = new Test3();
String  str = "a nn   aaaaadd  sdd sasd2312";
Map<Character ,Integer> token = t.getToken(str) ;
Iterator<Character> iterator = token.keySet().iterator();
int max = Collections.max(token.values());
while(iterator.hasNext()){
Character c = iterator.next();
if(token.get(c).compareTo(max) == 0){
System.out.println(c +" = "+token.get(c));
}
}
}

}

结果为: f max= 13

正确结果为: d max= 13

漏了个中间变量  否则永远输出的是最后个剩下的字母

public static void main(String[] args) {
String s = "sdfsddddddddddfffff,sdfsdf,";
s = s.replaceAll("[^a-zA-Z]", "");
int max = 0;
int temp = 0;
String tempString = "";
String maxString = "";
for (int i = 0; i < s.length(); i++) {
tempString = s.substring(0, 1);
String subs = s.replace(s.substring(0, 1), "");
temp = s.length() - subs.length();
if (max < temp) {
max = temp;
maxString = tempString;
}
s = subs;
}

System.out.println(maxString + " max= " + max);


}

用JAVA写，当然要用OOP的思想了，
/*******************************************************
实体类
package Str;

public class StrObject
{
private char name;

private int num;


/**
* @return the name
*/
public char getName() {
return name;
}

/**
* @param name the name to set
*/
public void setName(char name) {
this.name = name;
}

/**
* @return the num
*/
public int getNum() {
return num;
}

/**
* @param num the num to set
*/
public void setNum(int num) {
this.num += num;
}


}
/*************************************************************************
/*************************************************************************
主类
package Str;

import java.util.*;



public class Test
{
public static void main(String[] args)
{
String str = "asdfasd asdfwe.asdfasd,erytkcvm,drty  sdflkjgsdyvv5458sdgf 454df21f455asdf2r";
Test test = new Test();
test.test(str);
}

public void test(String str)
{
List list = new ArrayList();
for (int i = 0; i < str.length(); i++)
{
char c = str.charAt(i);
StrObject so = new StrObject();
so.setName(c);
so.setNum(1);
StrObject s = getObject(list, so);
if(s == null)
list.add(so);
else
s.setNum(1);
}
StrObject strObject = null;
for (int i = 0; i < list.size()-1; i++)
{
if(strObject == null)
{
strObject = (StrObject) list.get(i);
continue;
}
StrObject so = (StrObject) list.get(i);
if(so.getNum() > strObject.getNum())
strObject = so;
}
System.out.println("出现次数最多的："+strObject.getName()+"  数量："+strObject.getNum());
}

public StrObject getObject(List list,StrObject so)
{
for (int i = 0; i < list.size(); i++)
{
StrObject s = (StrObject) list.get(i);
if(s.getName() == so.getName())
return s;
else
continue;
}
return null;
}
}
/********************************************************************************

姐姐，发代码的时候请用[1code=1"1java1"][/1code1]括起来
test方法中的第一个for 循环的最后一句有逻辑错误。我在你的基础上修改了一下，同时也支持多个字符相同的情况。

	public void test(String str) {
		List list = new ArrayList();
		for (int i = 0; i < str.length(); i++) {
			char c = str.charAt(i);
			StrObject so = new StrObject();
			so.setName(c);
			so.setNum(1);
			StrObject s = getObject(list, so);
			if (s == null)
				list.add(so);
			else
				s.setNum(s.getNum() + 1);
		}
		StrObject strObject = null;
		Vector v = new Vector();
		for (int i = 0; i < list.size() - 1; i++) {
			if (strObject == null) {
				strObject = (StrObject) list.get(i);
				v.add(strObject);
				continue;
			}
			StrObject so = (StrObject) list.get(i);
			if (so.getNum() > strObject.getNum()){
				strObject = so;
				v.clear();
				v.add(so);
			}
			if (so.getNum() == strObject.getNum()){
				v.add(so);
			}
		}
		Iterator it = v.iterator();
		while(it.hasNext()){
			strObject = (StrObject)it.next();
			System.out.println("出现次数最多的：" + strObject.getName() + "  数量："
				+ strObject.getNum());
		}
		
	}

//简单实现了一下楼上的

import java.util.*;
public class Count {
    public static void main(String[] args) {
String str =  "hello wolrd wlllkdsfhksadfls?sdfls sdf.pqyutgvAAAxzsdfs lsdfj,ljsfd  ajfdsak sfksjdfisfsdkfj lsdfjsidf jsafdalsjfs sfskdfjs";
Map<Character,Integer> charMap = new HashMap<Character,Integer>();
for(char each : str.toCharArray()) {
if(charMap.containsKey(each)) {
charMap.put(each,charMap.get(each) + 1);
}else {
charMap.put(each,1);
}
}

Set set =charMap.keySet();   ///获得KEY
        Collection coll = charMap.values();  ///获得VALUE

        Iterator it = coll.iterator();  
        Iterator its = set.iterator();  
        while(it.hasNext())  
        {  
            System.out.println(its.next()+" :"+it.next());  
        }  
}
}

你们是学JAVA的也，一点OOP的思想都没有，

   天啦，楼主这样写啊，这是笔试题哦，如果答案是这样，考官都郁闷死了，谁会去看呢？
   这样的题目其实非常简单啊~~~先对字符串的内容排序（也可以变成字符数组排序），然后循环一下就可以了啊！
   只需要保留一个int变量保存上一个不同字符出现的个数就可以了。（如果考手写，使用commons-lang其实不太可能的）
   各位童鞋啊，如果笔试遇到这类问题，而且还是手写的，尽量往简单的想！