Remove characters from the first string which are present in the second string

// Java program to remove duplicates, the order of
// characters is not maintained in this program

public class GFG {
    static final int NO_OF_CHARS = 256;

    /* Returns an array of size 256 containing count
       of characters in the passed char array */
    static int[] getCharCountArray(String str)
    {
        int count[] = new int[NO_OF_CHARS];
        for (int i = 0; i < str.length(); i++)
            count[str.charAt(i)]++;

        return count;
    }

    /* removeDirtyChars takes two 
    string as arguments: First
    string (str)  is the one from 
    where function removes
    dirty characters. Second  
    string is the string which
    contain all dirty characters
    which need to be removed
    from first string */
    static String removeDirtyChars(String str,
                                   String mask_str)
    {
        int count[] = getCharCountArray(mask_str);
        int ip_ind = 0, res_ind = 0;

        char arr[] = str.toCharArray();

        while (ip_ind != arr.length)
        {
            char temp = arr[ip_ind];
            if (count[temp] == 0) {
                arr[res_ind] = arr[ip_ind];
                res_ind++;
            }
            ip_ind++;
        }

        str = new String(arr);

        /* After above step string is ngring.
        Removing extra "iittg" after string*/

        return str.substring(0, res_ind);
    }

    // Driver Code
    public static void main(String[] args)
    {
        String str = "geeksforgeeks";
        String mask_str = "mask";
        System.out.println(removeDirtyChars(str, mask_str));
    }
}

/*package whatever //do not write package name here */

import java.io.*;

class GFG {
    public static String removeChars(String string1,
                                     String string2)
    {
        // we extract every character of string string 2
        for (int index = 0; index < string2.length();
             index++) {
            char i = string2.charAt(index);
            // we find char exit or not
            while (string1.contains(i + "")) {
                int itr = string1.indexOf(i);
                // if char exit we simply remove that char
                string1 = string1.replace((i + ""), "");
            }
        }
        return string1;
    }

    // Driver Code
    public static void main(String[] args)
    {
        String string1, string2;
        string1 = "geeksforgeeks";
        string2 = "mask";
        System.out.println(removeChars(string1, string2));
    }
}
//This code is contributed by KaaL-EL.

import java.util.*;
public class GFG {
    static String removeChars(String s1, int n1, String s2,
                              int n2)
    {
        String s3 = "";

        // an array of size 26 to count the frequency of
        // characters
        int[] arr = new int[26];
        for (int i = 0; i < 26; i++) {
            arr[i] = 0;
        }
        for (int i = 0; i < n2;
             i++) // assigned all the index of characters
            // which are present
            arr[s2.charAt(i) - 'a']
                = -1; // in second string by -1
        // (just flagging)
        for (int i = 0; i < n1; i++) {
            if (arr[s1.charAt(i) - 'a'] != -1) {
                // Checking if the index of
                // characters don't have -1
                s3 += s1.charAt(
                    i); // i.e, that character was not
                // present in second string and
                // then storing that character
                // in string
            }
        }

        s1 = s3;
        return s1;
    }
    // driver code
    public static void main(String args[])
    {
        String string1 = "geeksforgeeks";
        String string2 = "mask";

        int n1 = string1.length();
        int n2 = string2.length();
        System.out.println(
            removeChars(string1, n1, string2, n2));
    }
}
// This code is contributed by Samim Hossain
// Mondal.