统计一句话中重复字符、单词的个数，HashMap，Queue List

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//统计一句话中重复字符的个数(Queue)-----------------------------package day081702;import java.util.ArrayList;import java.util.HashMap;import java.util.LinkedList;import java.util.List;import java.util.Map;import java.util.Queue;/** * 统计一句话中各个字符的个数 */public class MapDemo01 {    public static void main(String[] args) {        String str = "good good study, day day up.";        Queue<Character> queue = toQueue(str);//把一串字符串处理为只含有小写字母的队列Queue        Map<Character,Integer> map = new HashMap<Character,Integer>();        while(queue.size()>0){            Character c = queue.poll();//取出首元素，并做删除操作            if(!map.containsKey(c)){                map.put(c, 1);            }else{                map.put(c, map.get(c)+1);            }        }        System.out.println(map);    }    /**     * 把一串字符串处理为只含有小写字母的Queue     * （其他无关字符过滤掉）     * @param str     * @return Queue<Character>     */    public static Queue<Character> toQueue(String str){        //存储26个小写字母        List<Character> list26 = new ArrayList<Character>();        for(int i=0;i<26;i++){            Character c = (char)('a'+i);            list26.add(c);        }        //一旦是小写字母，存入queue        Queue<Character> queue = new LinkedList<Character>();        for(int i=0;i<str.length();i++){            Character c = str.charAt(i);//遍历每个字符            if(list26.contains(c)){//如果26个字母包含该字符，把该字符存入queue                queue.offer(c);            }        }        return queue;    }}//统计一句话中重复字符的个数(List)--------------------------------------package day081702;import java.util.ArrayList;import java.util.HashMap;import java.util.LinkedList;import java.util.List;import java.util.Map;import java.util.Queue;public class MapDemo02 {    public static void main(String[] args) {        String str = "good good study,day,day,up.";        List<Character> list = toList(str);//把一串字符串处理为只含有小写字母的List        Map<Character,Integer> map = new HashMap<Character,Integer>();        long start = System.currentTimeMillis();        for(int i=list.size()-1;i>=0;i--){            Character c = list.get(i);            if(!map.containsKey(c)){                map.put(c, 1);            }else{                map.put(c, map.get(c)+1);            }            list.remove(i);        }        System.out.println(map);        long end = System.currentTimeMillis();        System.out.println(end-start);    }    /**     * 把一串字符串处理为只含有小写字母的List     * （其他无关字符过滤掉）     * @param str     * @return List<Character>     */    public static List<Character> toList(String str){        //存储26个小写字母        List<Character> list26 = new ArrayList<Character>();        for(int i=0;i<26;i++){            Character c = (char)('a'+i);            list26.add(c);        }        //一旦是小写字母，存入list        List<Character> list = new ArrayList<Character>();        for(int i=0;i<str.length();i++){            Character c = str.charAt(i);//遍历每个字符            if(list26.contains(c)){//如果26个字母包含该字符，把该字符存入list                list.add(c);            }        }        return list;    }}//统计一句话中重复单词的个数--------------------------------------package day081702;import java.util.Arrays;import java.util.Iterator;import java.util.LinkedHashMap;import java.util.LinkedList;import java.util.Map;import java.util.Map.Entry;import java.util.Queue;import java.util.Set;/** * 统计一句话中重复单词的个数 */public class MapDemo03 {    public static void main(String[] args) {        String str = "good good study,    day day up.";        Queue<String> queue = toQueue(str);//toQueue()方法把String转为只包含单词的数组(过滤掉空格和标点符号)        /*         * 循环队列，放入map         */        Map<String,Integer> map = new LinkedHashMap<String,Integer>();//LinkedHashMap可按顺序循环输出        //Map<String,Integer> map = new HashMap<String,Integer>();//HashMap无顺序输出        while(queue.size()>0){            String key = queue.poll();//取出首元素，并做删除操作            if(!map.containsKey(key)){//如果不包含该key，则装入key，计数1                map.put(key, 1);            }else{                map.put(key, map.get(key)+1);//如果已经包含该key，则value增加1            }        }        /*         * 循环key         */        Set<String> keySet = map.keySet();        for(String setWord:keySet){//高级for循环            String word = setWord;            System.out.println(word+"的重复次数："+map.get(word));        }        Iterator<String> it = keySet.iterator();        while(it.hasNext()){//用Iterator来循环            String word = it.next();            System.out.println(word+"的重复次数："+map.get(word));        }        /*         * 循环Entry         */        Set<Entry<String,Integer>> entrySet = map.entrySet();        for(Entry<String,Integer> entry: entrySet){//高级for循环            String word = entry.getKey();            Integer num = entry.getValue();            System.out.println(word+"重复次数："+num);        }        Iterator<Entry<String,Integer>> entryIt = entrySet.iterator();        while(entryIt.hasNext()){//用Iterator来循环            Entry<String,Integer> tmpEntry = entryIt.next();            String word = tmpEntry.getKey();            Integer num = tmpEntry.getValue();            System.out.println(word+"重复次数：：："+num);        }    }    /**     * 把String转为只包含单词的数组(过滤掉空格和标点符号)     * @param str     * @return Queue<String>     */    public static Queue<String> toQueue(String str){        String regex = "\\,|\\.";        str = str.replaceAll(regex, " ");//把逗号点号转为空格        System.out.println(str);        String regex2 = "\\ +";        str = str.replaceAll(regex2, " ");//把多个空格转为1个空格        System.out.println(str);        String[] words = str.split(" ");//转为单词数组        System.out.println(Arrays.toString(words));        //数组转为队列queue        Queue<String> queue = new LinkedList<String>();        for(String word : words){            queue.offer(word);        }        return queue;    }}
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