如何比较两个字符串并尝试打印出逗号分隔符，但我无法避免重复一个以上的字符串

Question

I am comparing two strings and try to print out comman latters but i could not avoid to repeat a latter more than once. here is my code

public static String getCommonCharacters ( final String a, final String b){
    String result="";
    for(int i = 0; i < a.length(); i++){
        for(int j = 0; j < b.length(); j++)
            if(a.charAt(i)==b.charAt(j)){
                result +=a.charAt(i);
            }
    } return result;

the problem is when a = "baac" and b =" fdeabac " then i get out = "aabaac" instead of "abc" or "bca" etc

Answer 1

change the if condition to:

if (a.charAt(i) == b.charAt(j) && 
     !result.contains(String.valueOf(a.charAt(i)))) { ... }

Thus, you only perform the statement:

result +=a.charAt(i);

if the accumulating string doesn't already contain the character.

Answer 2

Working code with minor modification to yours:

public class StringCompare {
    public static String getCommonCharacters(final String a, final String b) {
        String result = "";
        for (int i = 0; i < a.length(); i++) {
            for (int j = 0; j < b.length(); j++)
                if (a.charAt(i) == b.charAt(j)) {
                    result += a.charAt(i);
                }
        }
        return result;
    }

    public static void main(String[] args) {

        System.out.println(getCommonCharacters("baac", "fdeabac ").replaceAll(
                "(.)\\1{1,}", "$1")); // You could use regular expressions for
                                        // that. Removing repeated characters.
    }
}

Output:

bac

Pattern explanation:

• " (.)\\1{1,} " means any character (added to group 1) followed by itself at least once

• " $1 " references contents of group 1

More about Regular Expressions Oracle Docs

Answer 3

Hier is another solution: create two new HashSet for each String which we change to charArray, then add them to hashSet with For loops, retainAll() method provide used to remove it's elements from a list that are not contained in the specified collection.@Java Doc by Oracle Last For-Loop used to concatenate char as a strings.

    String str ="";

    Set<Character> s1 = new HashSet<Character>();
    Set<Character> s2 = new HashSet<Character>();
    for(char c:a.toCharArray()) s1.add(c);

    for(char c:b.toCharArray()) s2.add(c);

    s1.retainAll(s2);
    for(char s:s1) str +=s;

   return str;