Bull: remove common characters

题目描述：

解题思路：

使用Java的HashMap集合框架,HashMap无重复值,将字符串2each character of the,然后遍历字符串1的每一个字符,判断map中是否存在该值,If it does not exist, it will be concatenated into a new string,No splicing if present.

代码：

import java.util.*;
public class Main{
    
    
    public  static void main (String[] args){
    
        
        Scanner scan = new Scanner(System.in); 
        String str1 = scan.nextLine();
        String str2 = scan.nextLine();
        
        HashMap<Character,Integer> map = new HashMap<> ();
        
        for(int i=0; i< str2.length() ;i++){
    
            if( map.get( str2.charAt(i))== null){
    
                map.put(str2.charAt(i),1);
            }else{
    
                map.put(str2.charAt(i),map.get(str2.charAt(i))+1);
            }
        } 
        
        String result="";
        
        for(int i=0; i< str1.length() ; i++){
    
            if(map.get(str1.charAt(i))==null){
    
                result+=str1.charAt(i);
            }
        }
        
        System.out.println(result);
    }
}