java 中字符串 arraylist 中字符串的频率

Question

I try this code cant any one help i can't find what the problem hear

public static List<Integer> matchingStrings(List<String> strings, List<String> queries) {
    // Write your code here
        int counter =0;
        List<Integer> q= new ArrayList<Integer>();
        for(int i = 0;i<queries.size();i++){
            for(int j=0;j<strings.size();j++){
                if(queries.get(i).equals(strings.get(j))){
                    counter= counter+1;
                }
            q.add(counter);
        }
            counter=0;
    }    
        return q;
}
}

Answer 1

You can use static frequency-method in Collections

int numberOfOccurrences = Collections.frequency(listOfStrings, "string_to_search");

Answer 2

initialize i and j as Instance Variables, you are ending their scope in for loops

List q= new ArrayList(); 
int i,j,counter; 
for(i = 0;i<queries.size();i++) {
    for(j=0;j<strings.size();j++) { 
        if(queries.get(i).equals(strings.get(j))) { 
            counter= counter+1; } q.add(counter);
    } counter=0; }
return q;

Answer 3

  List<Integer> results =new ArrayList<Integer>();

for(int i=0; i<queries.size(); i++){
    
    int count =0;
    for(int j=0; j<strings.size(); j++){
        if((queries.get(i)).equals(strings.get(j))){
          count ++;  
        } 
       
    }
    results.add(count); 
    count=0;
}
return results;