CodingBat: Java. String-1, Part IV

startWord:

public String startWord(String str, String word) {
		if (word.length() > str.length()) return "";
		if (str.substring(0, word.length()).equals(word)) return word;
		if (str.substring(1, word.length()).equals(word.substring(1)))
			return str.charAt(0) + word.substring(1);
		return "";
}

withoutX:

public String withoutX(String str) {
		if (str.length() == 0) return "";
		if (str.charAt(0) == 'x') str = str.substring(1);
		if (str.length() > 0 && str.charAt(str.length() - 1) == 'x')
			str = str.substring(0, str.length() - 1);
		return str;
}

withoutX2:

public String withoutX2(String str) {
		if (str.length() < 2) return "";

		String result = "";
		if (str.charAt(0) != 'x') result += str.charAt(0);
		if (str.charAt(1) != 'x') result += str.charAt(1);
		result += str.substring(2);
		return result;
}

The website said that “withoutX2” was a bit trickier than it looks like. However, the key is to not directly manipulate the input string but instead create a new one. Then this exercise is simpler than the preceding one.

7 thoughts on “CodingBat: Java. String-1, Part IV

  1. Patryk Dziedzic

    There is a little problem with withoutX2 function.
    If you put any parameter containing single sign different than “x”, the function will return empty string.
    As far as I understand the task, in this case the function should return copy of the parameter.
    Your function: withoutX2(“A”) -> “”
    Should be: withoutX2(“A”) -> “A”

    Reply
    1. Zack Wallmark

      It is true the withoutX2 would not compute properly for a value of “x” with the example given. Here is how I did it:

      public String withoutX2(String str) {
      if(str.length()==1 && str.substring(0,1).equals(“x”)) return “”;
      if(str.length()>=2){
      if(str.substring(0,2).equals(“xx”)) return str.substring(2);
      if(str.substring(0,1).equals(“x”)) return str.substring(1);
      if(str.substring(1,2).equals(“x”)) return str.substring(0,1)+str.substring(2);
      }
      return str;
      }

      P.S. Thanks for posting this, been running through these to get java fresh in my mind again and really helped having these when I got stuck.

      Reply
  2. Brandon Rogers

    I find a better solution to withoutX2 is this:

    public String withoutX2(String str) {
    if(str.length()>1){
    String temp = str.substring(0,2);
    str = str.substring(2);
    temp = temp.replace("x", "");
    return temp+str;
    }
    if (str.length()==1 && str.charAt(0)=='x')
    return "";
    return str;
    }

    Reply
    1. Gregor Ulm Post author

      How is this supposed to be better than my version? Besides, you shouldn’t use the inbuilt method replace() in this exercise.

      Reply
  3. Ahdiriony

    I decided as follows:
    public String withoutX2(String str) {
    if (str.length() < 2) return "";
    if (str.charAt(1) == 'x') {str = str.substring(0, 1) + str.substring(2);}
    if (str.charAt(0) == 'x') {str = str.substring(1);}
    return str;
    }

    Though it looks like your solution^..^

    Reply
  4. YONATAN ESTIVEN CANO MONTOYA

    Hi !
    Maybe this is a better solution 😀
    startWord

    public String startWord(String str, String word) {
    String ord = word.substring(1);
    if(str.length() >= 1){
    if(str.indexOf(ord)!= -1){
    return str.charAt(0)+””+ ord;
    }
    }
    return “”;
    }

    Reply

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