Suggestions needed for the removal of characters from the String

Question

I have written a program to remove the characters from the second string which are present in the first string.

I had Written a code for the above mentioned Problem Can someone Suggest Changes to make It efficient

class StrAssiQ5
{
  public static String Removal(String s,String s1)
  {
    StringBuffer a=new StringBuffer();;
    for(int i=0; i<s.length(); i++)
    {int count=0;
      for(int j=0; j<s1.length(); j++)
      {

        if(s.charAt(i)==s1.charAt(j))
        {
          count++;
        //a.append(Character.toString(s.charAt(i)));
        }
      }
      if (count==0)
      a.append(Character.toString(s.charAt(i)));
    }
    return a.toString();
  }
  public static void main(String [] args)
  {
    String s="Gaurav";
    String s1="Juneja";
    s=StrAssiQ5.Removal(s,s1);
    System.out.println(s);
  }
}

output is : Grv

I think this question is more suitable for http://codereview.stackexchange.com/ — Sweeper, Jun 19 '19 at 17:28

score 1 · Answer 1 · answered Jun 19 '19 at 17:31

1

Gaurav a better and efficient approach would be to use linked maps instead. Put all characters of first string in the linked map with frequencies as values and characters as keys. Using this kind of map will preserve the order too.

Then traverse the second string and accordingly reduce the frequencies from the map .

You will be left with the unique characters of first string.

Complexity : Max(length of A,length of B).

answered Jun 19 '19 at 17:31

vibhor vaish

153
1
13

I haven't studied Linked Map Yet – Gaurav Juneja Jun 19 '19 at 17:33
https://www.geeksforgeeks.org/linkedhashmap-class-java-examples/ . you could go through this (won't take much time) – vibhor vaish Jun 19 '19 at 17:34

score 0 · Answer 2 · answered Jun 19 '19 at 17:35

The general rule of thumb in computer science for this type of list difference operation is to use Set data structure. Java has HashSet class that can be used to that end. Create two HashSets from the elements of your strings. Then, you removeAll method that is inherited from Set class.

Documentation for removeAll

HashSet documentation

An example from SO

Suggestions needed for the removal of characters from the String

2 Answers2