How to check if the first 2 letters in a sting are a specific value

Question

Edit Thanks for the help guys got it working now.

So I had a question to do to ask a user for first name and last name which I have done no problem but then I thought it's be good to expand the program so that if someone entered a surname like McCabe it would print T McC instead of TM. I'm just not sure about how to compare the first two letters of the secondname string to see if they are "mc".

public class InitialsAlt {

  public static void main(String [] args){

    Scanner keyboardIn = new Scanner (System.in);
    String firstname = new String();
    System.out.print (" Enter your first name ");
    firstname = keyboardIn.nextLine();
    String secondname = new String();
    System.out.print (" Enter your second name ");
    secondname = keyboardIn.nextLine();

   if(secondname.charAt(0, 1)== "mc" ) {
      System.out.print("Your initals are " + firstname.charAt(0)+    secondname.charAt(0,1,2)); 
   }

   else {
   System.out.print("Your initals are " + firstname.charAt(0)+ secondname.charAt(0));
   }

  }
}

that's opening a can of worms as to all the possibilities of what last names can be... — andi, Dec 21 '15 at 15:28
[Obligatory link for question about names](http://www.kalzumeus.com/2010/06/17/falsehoods-programmers-believe-about-names/). — Andy Turner, Dec 21 '15 at 15:37

score 7 · Answer 1 · answered Dec 21 '15 at 15:27

7

if (secondName.toLowerCase().startsWith("mc")) {

answered Dec 21 '15 at 15:27

Reimeus

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Andy Turner · Answer 2 · 2015-12-21T15:40:22.677

2

The easiest way is to use String.startsWith:

yourString.toLowerCase().startsWith("mc")

If you want to avoid lowercasing the entire string or creating a new object, only to check the first two characters:

yourString.length() >= 2
&& Character.toLowerCase(yourString.charAt(0)) == 'm'
&& Character.toLowerCase(yourString.charAt(1)) == 'c'

However, I would use the former solution as it is far more readable, and the performance hit from lowercasing the entire string is almost certainly negligible, unless you are doing this on quite large strings.

edited Dec 21 '15 at 15:40

answered Dec 21 '15 at 15:30

Andy Turner

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The most efficient solution i guess :P – TheLostMind Dec 21 '15 at 15:31
@VinodMadyalkar Yeah. I was kinda going off your answer of "will be faster than...", although I admit it is a pretty ridiculous solution. – Andy Turner Dec 21 '15 at 15:34
For checking first 2 chars.. I think its readable.. It would become a mess if you had to check first 7 chars – TheLostMind Dec 21 '15 at 15:35

score 1 · Answer 3 · answered Dec 21 '15 at 15:27

1

Use substring to get the first two letters, then convert to lowercase, then check to see if it equals:

String someString = "McElroy";
if (someString.subString(0,2).toLowerCase().equals("mc")) {
    //do something
}

answered Dec 21 '15 at 15:27

Rabbit Guy

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TheLostMind · Accepted Answer · 2015-12-21T15:51:19.553

1

Use yourString.toLowerCase().indexOf("mc")==0. This will involve creation of a new String only once (Since indexOf() doesn't create a new one, using indexOf() would be better than using subString() here)

edited Dec 21 '15 at 15:51

answered Dec 21 '15 at 15:28

TheLostMind

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I don't think `toLowerCase()` will be faster than `substring()`; both allocate a new String object, but toLowerCase involves creating a new `char[]` and processing each character to perform the transformation. `.substring()` just passes the indexes to `String()` and shares the existing `char[]`. – dsh Dec 21 '15 at 15:46

Tarik · Answer 5 · 2015-12-21T15:39:30.977

1

If its case insensitive you could use the Apache Commons Lang library:

if(StringUtils.startsWithIgnoreCase(secondname, "mc") {
  // Do nice stuff
}

Otherwise, you can use:

if(StringUtils.startsWith(secondname.toLowerCase(), "mc") {
  // Do nice stuff
}

edited Dec 21 '15 at 15:39

answered Dec 21 '15 at 15:33

Tarik

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How to check if the first 2 letters in a sting are a specific value

5 Answers5