Java 中Map的使用，以及遍历

迷南。 2022-09-18 04:58 122阅读 0赞

[http://poj.org/problem?id=1002][http_poj.org_problem_id_1002]

/*
     * 1. 用TreeMap<String,Integer>;
     * 2. 接收字符串，逐个判断，数字直接相加，字符转换成数字，‘-’不管，组成的字符串放到Map
     * 3. 输出Map中value>1的项
     * 
     * */
    
    import java.util.*;
    
    public class Main {
    	public static void main(String[] args) {
    		//jdk1.6以下的不能这样定义 TreeMap <String,Integer> map = new TreeMap<>();
    		TreeMap <String,Integer> map = new TreeMap<String,Integer>();  
    		Scanner cin = new Scanner(System.in);
    		int t = cin.nextInt();
    		String s,str;
    		char ch;
    		int i;
    		while(t--!=0){
    			s = cin.next();
    			str = "";
    			for(i=0;i<s.length();i++){
    				ch = s.charAt(i);
    				if(ch>='0' && ch<='9') str += ch+"";
    				else if(ch=='-') continue;
    				else{
    					switch (ch) {
    						case 'A':case 'B':case 'C':  str += "2"; break;
    						case 'D':case 'E':case 'F':  str += "3"; break;
    						case 'G':case 'H':case 'I':  str += "4"; break;
    						case 'J':case 'K':case 'L':  str += "5"; break;
    						case 'M':case 'N':case 'O':  str += "6"; break;
    						case 'P':case 'R':case 'S':  str += "7"; break;
    						case 'T':case 'U':case 'V':  str += "8"; break;
    						case 'W':case 'X':case 'Y':  str += "9"; break;
    					}
    				}
    				if(str.length() == 3) str += "-";
    			}
    			int cnt;
    			if(map.containsKey(str))  {
    				cnt = map.get(str)+1;
    				map.remove(str);
    				map.put(str, cnt);
    			}else{
    				map.put(str, 1);
    			}
    		}
    		Iterator<String> it = map.keySet().iterator();
    		String key;int num;
    		int flag = 0;
    		while(it.hasNext()){
    			key = it.next();
    			num = map.get(key);
    			if( num>1 ){
    				flag = 1;System.out.println(key+" "+ num);
    			}
    		}
    		if(flag==0)System.out.println("No duplicates.");
    	}
    }

[http_poj.org_problem_id_1002]: http://poj.org/problem?id=1002