Finding strings with consecutive characters in Java

user3003961 Published at Dev

user3003961

Write a function in Java which takes an Array of strings and from the array of strings returns only those strings which have a consecutive repetition of a particular letter for eg: if I/P is

{"Dauresselam", "slab", "fuss", "boolean", "clap"}

then O/P should be

{"Dauresselam", "fuss", "boolean"}

I could solve it using

import java.util.Scanner;
public class doubleChars {
    public static String[] getDoubles(String[]In)
    {

        int inLen=In.length;
        String zoom[]=new String[inLen];
        int count=0;
        if(inLen==0)
        {
            return zoom;
        }
        for(int i=0;i<=inLen-1;i++)
        {
            String A=In[i];
            //System.out.println(A);
            int striLen=A.length();
            for(int j=0;j<striLen-1;j++)
            {

                if(A.substring(j, j+1).equals(A.substring(j+1, j+2)))
                {
                    zoom[count]=A;
                    count++;
                    break;
                }
            }

        }
          return zoom;
        }
     public static void main(String[] args)
     {
         char more='y';
         int ab=0;
        String[] res={};
        String[] fillMe={"durres", "murres", "", "abcdeee", "boolean", "nger", "lagger"};
        Scanner strobe=new Scanner(System.in);
        System.out.println("Please enter the arraye of the string");
        /*while(strobe.hasNext())
        {
            fillMe[ab]=strobe.next();

            ab++;
        }
        */
        res=doubleChars.getDoubles(fillMe);
        for(int k=0;k<res.length;k++)
        {
            if(res[k]==null)
            {
                break;
            }
        System.out.println(res[k]);
        }
    }
}

IS there a way to use regex to make it shorter?

sp00m

You could use a backreference:

([a-z])\1

Regular expression visualization

Visualization by Debuggex

Java example:

String[] strings = { "Dauresselam", "slab", "fuss", "boolean", "clap" };

String regex = "([a-z])\\1";
Pattern pattern = Pattern.compile(regex);

for (String string : strings) {
    Matcher matcher = pattern.matcher(string);
    if (matcher.find()) {
        System.out.println(string);
    }
}

Prints: