wordEnds java challenge

Improvement to approach would be to do yourself instead of asking others to pass your exam.

public String wordEnds(String str, String word) {
   return str.replaceAll("(?:(?!.?"+word+").)*(?:(.)?"+word+"(?=(.)"+word+")?"+"(?="+word+"(?<=(.)))?(.)?)?","$1$2$4$3");
}
// this could be easier using matcher.group() instead of replaceAll(), but I don't see a way to include java.util.regex.Matcher from codingbat

i was not clear on challenge

wordEnds("abcXY123XYijk", "XY") → "c13i"//this is where c and i are coming?
wordEnds("XY123XY", "XY") → "13"//how 13 came?
wordEnds("XY1XY", "XY") → "11"//how 11 came?

wordEnds("abcXY123XYijk", "XY") → "c13i"//this is where c and i are coming?
this is where c and 1 are coming
i is coming from
wordEnds("abcXY123XYijk", "XY") → "c13i"

wordEnds("XY123XY", "XY") → "13"//how 13 came?
wordEnds("XY123XY", "XY") → "13"
wordEnds("XY123XY", "XY") → "13"

wordEnds("XY1XY", "XY") → "11"//how 11 came?
wordEnds("XY1XY", "XY") → "11"
wordEnds("XY1XY", "XY") → "11"

wordEnds("abcXY123XYijk", "XY") → "c13i"//this is where c and i are coming?
this is where c and 1 are coming
i is coming from
wordEnds("abcXY123XYijk", "XY") → "c13i"

why 2 is filtered out ??
if more than one word( XY) say two word(XY) as above which word(XY) we have to consider first XY or second XY to identify

return a string made of each char just before and just after every appearance of the word in the string. I

i think now i understand
we want each before each after characters for every occurence of word..

public class WordEndsEx {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub

       System.out.println("value is----"+wordEnds("abcXY123XYijk", "XY")); //"c13i"
	}

	
	public static String wordEnds(String str, String word) {
		int xyPos=str.indexOf("XY");
		int xyPosition=str.lastIndexOf("XY");
		System.out.println("xyPos"+xyPos);
		System.out.println("xyPosition"+xyPosition);
		String s1=str.substring(xyPos-1,xyPos);
		String s2=str.substring(xyPos+2,xyPos+3);
		//String s2=str.replaceAll(str,word);
		String s3=str.substring(xyPosition-1,xyPosition);
		String s4=str.substring(xyPosition+2,xyPosition+3);
		System.out.println("s1 is"+s1);
		System.out.println("s2 is"+s2);
		System.out.println("s3 is"+s3);
		System.out.println("s4 is"+s4);
		//String s4=str.replaceAll(str,word);
		//String s5=s1+s2;
		//String s6=s3+s4;
		String s7=s1+s2+s3+s4;
		return s7;
		  
		}
}

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above gave below correct result.

xyPos3
xyPosition8
s1 isc
s2 is1
s3 is3
s4 isi
value is----c13i


how to improve my code above?
please advise

public String wordEnds(String str, String word) {
int xyPos=str.indexOf("XY");
		int xyPosition=str.lastIndexOf("XY");
		//System.out.println("xyPos"+xyPos);
		//System.out.println("xyPosition"+xyPosition);
		String s1=str.substring(xyPos-1,xyPos);
		String s2=str.substring(xyPos+2,xyPos+3);
		//String s2=str.replaceAll(str,word);
		String s3=str.substring(xyPosition-1,xyPosition);
		String s4=str.substring(xyPosition+2,xyPosition+3);
		//System.out.println("s1 is"+s1);
		//System.out.println("s2 is"+s2);
		//System.out.println("s3 is"+s3);
		//System.out.println("s4 is"+s4);
		//String s4=str.replaceAll(str,word);
		//String s5=s1+s2;
		//String s6=s3+s4;
		String s7=s1+s2+s3+s4;
		return s7;
  
}

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above failing test cases as below.

Expected	Run		
wordEnds("abcXY123XYijk", "XY") → "c13i"	"c13i"	OK	    
wordEnds("XY123XY", "XY") → "13"	"Exception:java.lang.StringIndexOutOfBoundsException: String index out of range: -1 (line number:6)"	X	    
wordEnds("XY1XY", "XY") → "11"	"Exception:java.lang.StringIndexOutOfBoundsException: String index out of range: -1 (line number:6)"	X	    
wordEnds("XYXY", "XY") → "XY"	"Exception:java.lang.StringIndexOutOfBoundsException: String index out of range: -1 (line number:6)"	X	    
wordEnds("XY", "XY") → ""	"Exception:java.lang.StringIndexOutOfBoundsException: String index out of range: -1 (line number:6)"	X	    
wordEnds("Hi", "XY") → ""	"Exception:java.lang.StringIndexOutOfBoundsException: String index out of range: -2 (line number:6)"	X	    
wordEnds("", "XY") → ""	"Exception:java.lang.StringIndexOutOfBoundsException: String index out of range: -2 (line number:6)"	X	    
wordEnds("abc1xyz1i1j", "1") → "cxziij"	"Exception:java.lang.StringIndexOutOfBoundsException: String index out of range: -2 (line number:6)"	X	    
wordEnds("abc1xyz1", "1") → "cxz"	"Exception:java.lang.StringIndexOutOfBoundsException: String index out of range: -2 (line number:6)"	X	    
wordEnds("abc1xyz11", "1") → "cxz11"	"Exception:java.lang.StringIndexOutOfBoundsException: String index out of range: -2 (line number:6)"	X	    
wordEnds("abc1xyz1abc", "abc") → "11"	"Exception:java.lang.StringIndexOutOfBoundsException: String index out of range: -2 (line number:6)"	X	    
wordEnds("abc1xyz1abc", "b") → "acac"	"Exception:java.lang.StringIndexOutOfBoundsException: String index out of range: -2 (line number:6)"	X	    
wordEnds("abc1abc1abc", "abc") → "1111"	"Exception:java.lang.StringIndexOutOfBoundsException: String index out of range: -2 (line number:6)"	X	    
other tests
X	 

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please advise

public String wordEnds(String str, String word) {
int xyPos=str.indexOf("XY");
		int xyPosition=str.lastIndexOf("XY");
		//System.out.println("xyPos"+xyPos);
		//System.out.println("xyPosition"+xyPosition);
if(xyPos>=1 && xyPosition>=1){
		String s1=str.substring(xyPos-1,xyPos);
		String s2=str.substring(xyPos+2,xyPos+3);
		//String s2=str.replaceAll(str,word);
		String s3=str.substring(xyPosition-1,xyPosition);
		String s4=str.substring(xyPosition+2,xyPosition+3);
		//System.out.println("s1 is"+s1);
		//System.out.println("s2 is"+s2);
		//System.out.println("s3 is"+s3);
		//System.out.println("s4 is"+s4);
		//String s4=str.replaceAll(str,word);
		//String s5=s1+s2;
		//String s6=s3+s4;
		String s7=s1+s2+s3+s4;
		return s7;
}
else
return "hello";
  
}

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Expected      Run            
wordEnds("abcXY123XYijk", "XY") → "c13i"      "c13i"      OK         
wordEnds("XY123XY", "XY") → "13"      "hello"      X         
wordEnds("XY1XY", "XY") → "11"      "hello"      X         
wordEnds("XYXY", "XY") → "XY"      "hello"      X         
wordEnds("XY", "XY") → ""      "hello"      X         
wordEnds("Hi", "XY") → ""      "hello"      X         
wordEnds("", "XY") → ""      "hello"      X         
wordEnds("abc1xyz1i1j", "1") → "cxziij"      "hello"      X         
wordEnds("abc1xyz1", "1") → "cxz"      "hello"      X         
wordEnds("abc1xyz11", "1") → "cxz11"      "hello"      X         
wordEnds("abc1xyz1abc", "abc") → "11"      "hello"      X         
wordEnds("abc1xyz1abc", "b") → "acac"      "hello"      X         
wordEnds("abc1abc1abc", "abc") → "1111"      "hello"      X         
other tests
X

how to fix above tests.

public class WordEndsEx {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub

      // System.out.println("value is----"+wordEnds("abcXY123XYijk", "XY")); //"c13i"
       System.out.println("value is----"+wordEnds("XY123XY", "XY")); //"13"
	}

	
	public static String wordEnds(String str, String word) {
	int xyPos=str.indexOf("XY");
	int xyPosition=str.lastIndexOf("XY");
	//System.out.println("xyPos"+xyPos);
	//System.out.println("xyPosition"+xyPosition);
if(xyPos>=1 && xyPosition>=1){
	String s1=str.substring(xyPos-1,xyPos);
	String s2=str.substring(xyPos+2,xyPos+3);
	//String s2=str.replaceAll(str,word);
	String s3=str.substring(xyPosition-1,xyPosition);
	String s4=str.substring(xyPosition+2,xyPosition+3);
	//System.out.println("s1 is"+s1);
	//System.out.println("s2 is"+s2);
	//System.out.println("s3 is"+s3);
	//System.out.println("s4 is"+s4);
	//String s4=str.replaceAll(str,word);
	//String s5=s1+s2;
	//String s6=s3+s4;
	String s7=s1+s2+s3+s4;
	return s7;
}
else if(xyPos==0 && (    xyPosition>=1&&(  (str.length()-xyPosition >=3)) )    ){
	String s1="";
	System.out.println("s1 is-->"+s1);
	String s2=str.substring(xyPos+2,xyPos+3);
	System.out.println("s2 is-->"+s2);
	//String s2=str.replaceAll(str,word);
	
	String s3=str.substring(xyPosition-1,xyPosition);
	System.out.println("s3 is-->"+s3);
	String s4=str.substring(xyPosition+2,xyPosition+3);
	System.out.println("s4 is-->"+s4);
	//System.out.println("s1 is"+s1);
	//System.out.println("s2 is"+s2);
	//System.out.println("s3 is"+s3);
	//System.out.println("s4 is"+s4);
	//String s4=str.replaceAll(str,word);
	//String s5=s1+s2;
	//String s6=s3+s4;
	String s7=s1+s2+s3+s4;
	return s7;
}


else if(xyPos>=1 && xyPosition==0){
	String s1=str.substring(xyPos-1,xyPos);
	String s2=str.substring(xyPos+2,xyPos+3);
	//String s2=str.replaceAll(str,word);
	String s3=str.substring(xyPosition-1,xyPosition);
	String s4="";
	//System.out.println("s1 is"+s1);
	//System.out.println("s2 is"+s2);
	//System.out.println("s3 is"+s3);
	//System.out.println("s4 is"+s4);
	//String s4=str.replaceAll(str,word);
	//String s5=s1+s2;
	//String s6=s3+s4;
	String s7=s1+s2+s3+s4;
	return s7;
}

else
return "hello";}
}

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tried like above but not working

public class WordEndsEx {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub

      // System.out.println("value is----"+wordEnds("abcXY123XYijk", "XY")); //"c13i"
     //  System.out.println("value is----"+wordEnds("XY123XY", "XY")); //"13"
       //System.out.println("value is----"+wordEnds("hi", "XY")); //""
       System.out.println("value is---"+wordEnds("abc1xyz1i1j", "1"));//"cxziij"
	}

	
	public static String wordEnds(String str, String word) {
		int xyPos=str.indexOf(word);
	int xyPosition=str.lastIndexOf(word);
	System.out.println("xyPos"+xyPos);
	System.out.println("xyPosition"+xyPosition);
if(xyPos>=1 && xyPosition>=1){
	String s1=str.substring(xyPos-1,xyPos);
	String s2;
	if(str.length()-xyPosition>=3){
	s2=str.substring(xyPos+2,xyPos+3);
	}
	else{
		s2="";
	}
		
	//String s2=str.replaceAll(str,word);
	String s3=str.substring(xyPosition-1,xyPosition);
	//String s4=str.substring(xyPosition+2,xyPosition+3);
	String s4;
	if(str.length()-xyPosition>=3){
	s4=str.substring(xyPos+2,xyPos+3);
	}
	else{
		s4="";
	}
	//System.out.println("s1 is"+s1);
	//System.out.println("s2 is"+s2);
	//System.out.println("s3 is"+s3);
	//System.out.println("s4 is"+s4);
	//String s4=str.replaceAll(str,word);
	//String s5=s1+s2;
	//String s6=s3+s4;
	String s7=s1+s2+s3+s4;
	return s7;
}
else if(xyPos<=0 && xyPosition>=1){
	String s1="";
	//System.out.println("s1 is-->"+s1);
	String s2=str.substring(xyPos+2,xyPos+3);
	//System.out.println("s2 is-->"+s2);
	//String s2=str.replaceAll(str,word);
	
	String s3=str.substring(xyPosition-1,xyPosition);
	//System.out.println("s3 is-->"+s3);
	String s4;
	if(str.length()-xyPosition >=3){
	s4=str.substring(xyPosition+2,xyPosition+3);
	}else{
		s4="";
	}
	//System.out.println("s4 is-->"+s4);
	//System.out.println("s1 is"+s1);
	//System.out.println("s2 is"+s2);
	//System.out.println("s3 is"+s3);
	//System.out.println("s4 is"+s4);
	//String s4=str.replaceAll(str,word);
	//String s5=s1+s2;
	//String s6=s3+s4;
	String s7=s1+s2+s3+s4;
	return s7;
}


else if(xyPos>=1 && xyPosition<=0){
	String s1=str.substring(xyPos-1,xyPos);
	String s2=str.substring(xyPos+2,xyPos+3);
	//String s2=str.replaceAll(str,word);
	String s3=str.substring(xyPosition-1,xyPosition);
	String s4="";
	//System.out.println("s1 is"+s1);
	//System.out.println("s2 is"+s2);
	//System.out.println("s3 is"+s3);
	//System.out.println("s4 is"+s4);
	//String s4=str.replaceAll(str,word);
	//String s5=s1+s2;
	//String s6=s3+s4;
	String s7=s1+s2+s3+s4;
	return s7;
}


else if(xyPos<=0 && xyPosition<=0){
	System.out.println("here");
	return "";
}

else
return "hello";}
}

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i got wrong output
xyPos3
xyPosition9
value is---ci

public String wordEnds(String str, String word) {

	int xyPos=str.indexOf("XY");
	int xyPosition=str.lastIndexOf("XY");
	//System.out.println("xyPos"+xyPos);
	//System.out.println("xyPosition"+xyPosition);
       if(xyPos>=1 && xyPosition>=1){
	String s1=str.substring(xyPos-1,xyPos);
	String s2=str.substring(xyPos+2,xyPos+3);
	//String s2=str.replaceAll(str,word);
	String s3=str.substring(xyPosition-1,xyPosition);
	String s4=str.substring(xyPosition+2,xyPosition+3);
	//System.out.println("s1 is"+s1);
	//System.out.println("s2 is"+s2);
	//System.out.println("s3 is"+s3);
	//System.out.println("s4 is"+s4);
	//String s4=str.replaceAll(str,word);
	//String s5=s1+s2;
	//String s6=s3+s4;
	String s7=s1+s2+s3+s4;
	return s7;
}
else if(xyPos<=0 && xyPosition>=1){
	String s1="";
	//System.out.println("s1 is-->"+s1);
	String s2=str.substring(xyPos+2,xyPos+3);
	//System.out.println("s2 is-->"+s2);
	//String s2=str.replaceAll(str,word);
	
	String s3=str.substring(xyPosition-1,xyPosition);
	//System.out.println("s3 is-->"+s3);
	String s4;
	if(str.length()-xyPosition >=3){
	s4=str.substring(xyPosition+2,xyPosition+3);
	}else{
		s4="";
	}
	//System.out.println("s4 is-->"+s4);
	//System.out.println("s1 is"+s1);
	//System.out.println("s2 is"+s2);
	//System.out.println("s3 is"+s3);
	//System.out.println("s4 is"+s4);
	//String s4=str.replaceAll(str,word);
	//String s5=s1+s2;
	//String s6=s3+s4;
	String s7=s1+s2+s3+s4;
	return s7;
}


else if(xyPos>=1 && xyPosition<=0){
	String s1=str.substring(xyPos-1,xyPos);
	String s2=str.substring(xyPos+2,xyPos+3);
	//String s2=str.replaceAll(str,word);
	String s3=str.substring(xyPosition-1,xyPosition);
	String s4="";
	//System.out.println("s1 is"+s1);
	//System.out.println("s2 is"+s2);
	//System.out.println("s3 is"+s3);
	//System.out.println("s4 is"+s4);
	//String s4=str.replaceAll(str,word);
	//String s5=s1+s2;
	//String s6=s3+s4;
	String s7=s1+s2+s3+s4;
	return s7;
}


else if(xyPos<=0 && xyPosition<=0){
	
	return "";
}

else
return "hello";
  
}

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Expected      Run            
wordEnds("abcXY123XYijk", "XY") → "c13i"      "c13i"      OK         
wordEnds("XY123XY", "XY") → "13"      "13"      OK         
wordEnds("XY1XY", "XY") → "11"      "11"      OK         
wordEnds("XYXY", "XY") → "XY"      "XY"      OK         
wordEnds("XY", "XY") → ""      ""      OK         
wordEnds("Hi", "XY") → ""      ""      OK         
wordEnds("", "XY") → ""      ""      OK         
wordEnds("abc1xyz1i1j", "1") → "cxziij"      ""      X         
wordEnds("abc1xyz1", "1") → "cxz"      ""      X         
wordEnds("abc1xyz11", "1") → "cxz11"      ""      X         
wordEnds("abc1xyz1abc", "abc") → "11"      ""      X         
wordEnds("abc1xyz1abc", "b") → "acac"      ""      X         
wordEnds("abc1abc1abc", "abc") → "1111"      ""      X         
other tests
X         
Your progress graph for this problem

please advise

how to write without using regular expression?

let me understand

public class WordEnds {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		/*
		 * Given a string and a non-empty word string, return a string made of
		 * each char just before and just after every appearance of the word in
		 * the string. Ignore cases where there is no char before or after the
		 * word, and a char may be included twice if it is between two words.
		 * 
		 * wordEnds("abcXY123XYijk", "XY") → "c13i" wordEnds("XY123XY", "XY") →
		 * "13" wordEnds("XY1XY", "XY") → "11"
		 */
		System.out.println("is--->" + wordEnds("abcXY123XYijk", "XY"));

	}

	public static String wordEnds(String str, String word) {
		String ends = "";
		for (int i = 0; i < str.length(); ++i) {
			if (str.startsWith(word, i)) {
				if (i > 0) {
					ends += str.substring(i - 1, i);
					System.out.println("end is--->"+ends);
				}
				if (i + word.length() < str.length()) {
					ends += str.substring(i + word.length(), i + word.length() + 1);
					System.out.println("end isss--->"+ends);
				}
			}
		}
		return ends;
	}

}

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above gave below output
end is--->c
end isss--->c1
end is--->c13
end isss--->c13i
is--->c13i

when i try to debug it is strting with i=3 not i=0 for unknown reason. please advise
IValue.jpg

when str="abcXY123XYijk", word="XY", and i=0,
what is str.startsWith(word, i)?

when str="abcXY123XYijk", word="XY", and i=0,
what is str.startsWith(word, i)?

true right as XY is at index 3 but i stilll though eclipse debugger should have strted with i=0 not i=3. please advise

If you are looking at line 25, you don't  get to line 25 when i=0

If you are looking at line 25, you don't  get to line 25 when i=0

so ariable values on right hand side specific to a line number like 25?

i though i got assigned some value at line 23 which should carry forward?

please advise

i got assigned the value 0 in line 22
when i was 0, line 25 was not executed
then i got incremeted from 0 to 1 in line 22
when i was 1, line 25 was not executed
then i got incremeted from 1 to 2 in line 22
when i was 2, line 25 was not executed
then i got incremeted from 2 to 3 in line 22
when i was 3, line 25 was executed, and the value of i at that time was 3.

by putting break point at 22 i can see right

i got assigned the value 0 in line 22
when i was 0, line 25 was not executed
then i got changed from 0 to 1 in line 22
when i was 1, line 25 was not executed
then i got changed from 1 to 2 in line 22
when i was 2, line 25 was not executed
then i got changed from 2 to 3 in line 22
when i was 3, line 25 was executed, and the value of i at that time was 3.

public String wordEnds(String str, String word) {
   return str.replaceAll("(?:(?!.?"+word+").)*(?:(.)?"+word+"(?=(.)"+word+")?"+"(?="+word+"(?<=(.)))?(.)?)?","$1$2$4$3");
}
// this could be easier using matcher.group() instead of replaceAll(), but I don't see a way to include java.util.regex.Matcher from codingbat

can you please advise on above. I was not clear what is going on?

I don't think that's a good way to do it, it's too awkward to reconcile the way the challenge wants to handle overlaps within the way replaceAll wants to handle them.
(it might be a little easier if there was a character that was guaranteed to never occur in str, but it's still probably easier to do this challenge with a loop)

if (i + word.length() < str.length()

i wonder why we are checking above if condition?

i see
for loop has one top level if which has two bottom  level if loops which are filling before and after character of xy ie word

      if (i > 0) {
                              ends += str.substring(i - 1, i);
                              System.out.println("end is--->"+ends);
                        }
                        if (i + word.length() < str.length()) {
                              ends += str.substring(i + word.length(), i + word.length() + 1);
                              System.out.println("end isss--->"+ends);
                        }

public class WordEnds {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		/*
		 * Given a string and a non-empty word string, return a string made of
		 * each char just before and just after every appearance of the word in
		 * the string. Ignore cases where there is no char before or after the
		 * word, and a char may be included twice if it is between two words.
		 * 
		 * wordEnds("abcXY123XYijk", "XY") → "c13i" wordEnds("XY123XY", "XY") →
		 * "13" wordEnds("XY1XY", "XY") → "11"
		 */
		System.out.println("is--->" + wordEnds("abcXY123XYijk", "XY"));

	}

	public static String wordEnds(String str, String word) {
		String ends = "";
		for (int i = 0; i < str.length(); ++i) {
			if (str.startsWith(word, i)) {
				if (i > 0) {
					ends += str.substring(i - 1, i);
					System.out.println("end is--->"+ends);
				}
				if (i + word.length() < str.length()) {
					ends += str.substring(i + word.length(), i + word.length() + 1);
					System.out.println("end isss--->"+ends);
				}
			}
		}
		return ends;
	}

}

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public class WordEnds {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		/*
		 * Given a string and a non-empty word string, return a string made of
		 * each char just before and just after every appearance of the word in
		 * the string. Ignore cases where there is no char before or after the
		 * word, and a char may be included twice if it is between two words.
		 * 
		 * wordEnds("abcXY123XYijk", "XY") → "c13i" wordEnds("XY123XY", "XY") →
		 * "13" wordEnds("XY1XY", "XY") → "11"
		 */
		System.out.println("is--->" + wordEnds("abcXY123XYijk", "XY"));

	}

	public static String wordEnds(String str, String word) {
		String ends = "";
		for (int i = 0; i < str.length(); ++i) {
			if (str.startsWith(word, i)) {
				if (i > 0) {
					ends += str.substring(i - 1, i);
					System.out.println("end is--->"+ends);
				}
				if (i > 0) {//here i changed condition as i>0
					ends += str.substring(i + word.length(), i + word.length() + 1);
					System.out.println("end isss--->"+ends);
				}
			}
		}
		return ends;
	}

}

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above also worked fine gave same output
end is--->c
end isss--->c1
end is--->c13
end isss--->c13i
is--->c13i

with
if (i > 0) {//here i changed condition as i>0

Expected      Run
wordEnds("XY123XY", "XY") → "13"      "Exception:java.lang.StringIndexOutOfBoundsException: String index out of range: 8 (line number:10)"

public class WordEnds {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		/*
		 * Given a string and a non-empty word string, return a string made of
		 * each char just before and just after every appearance of the word in
		 * the string. Ignore cases where there is no char before or after the
		 * word, and a char may be included twice if it is between two words.
		 * 
		 * wordEnds("abcXY123XYijk", "XY") → "c13i" wordEnds("XY123XY", "XY") →
		 * "13" wordEnds("XY1XY", "XY") → "11"
		 */
		System.out.println("is--->" + wordEnds("XY123XY", "XY"));

	}

	public static String wordEnds(String str, String word) {
		String ends = "";
		for (int i = 0; i < str.length(); ++i) {
			if (str.startsWith(word, i)) {
				if (i > 0) {
					ends += str.substring(i - 1, i);
					System.out.println("end is--->"+ends);
				}
				if (i > 0) {//here i changed condition as i>0
					ends += str.substring(i + word.length(), i + word.length() + 1);
					System.out.println("end isss--->"+ends);
				}
			}
		}
		return ends;
	}

}

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correct above failed with below message
end is--->3
Exception in thread "main" java.lang.StringIndexOutOfBoundsException
      at java.lang.String.substring(String.java:1148)
      at WordEnds.wordEnds(WordEnds.java:28)
      at WordEnds.main(WordEnds.java:15)

so below is needed in bottome if to pass all tests?

if(i + word.length() < str.length()) not if if (i > 0)

public class WordEnds {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		/*
		 * Given a string and a non-empty word string, return a string made of
		 * each char just before and just after every appearance of the word in
		 * the string. Ignore cases where there is no char before or after the
		 * word, and a char may be included twice if it is between two words.
		 * 
		 * wordEnds("abcXY123XYijk", "XY") → "c13i" wordEnds("XY123XY", "XY") →
		 * "13" wordEnds("XY1XY", "XY") → "11"
		 */
		System.out.println("is--->" + wordEnds("XY123XY", "XY"));

	}

	public static String wordEnds(String str, String word) {
		String ends = "";
		for (int i = 0; i < str.length(); ++i) {
			if (str.startsWith(word, i)) {
				if (i > 0) {
					ends += str.substring(i - 1, i);
					System.out.println("end is--->"+ends);
				}
				if (i > 0) {//here i changed condition as i>0 not if(i + word.length() < str.length())
					ends += str.substring(i + word.length(), i + word.length() + 1);
					System.out.println("end isss--->"+ends);
				}
			}
		}
		return ends;
	}

}

Select allOpen in new window

public class WordEnds {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		/*
		 * Given a string and a non-empty word string, return a string made of
		 * each char just before and just after every appearance of the word in
		 * the string. Ignore cases where there is no char before or after the
		 * word, and a char may be included twice if it is between two words.
		 * 
		 * wordEnds("abcXY123XYijk", "XY") → "c13i" wordEnds("XY123XY", "XY") →
		 * "13" wordEnds("XY1XY", "XY") → "11"
		 */
		System.out.println("is--->" + wordEnds("XY123XY", "XY"));

	}

	public static String wordEnds(String str, String word) {
		String ends = "";
		for (int i = 0; i < str.length(); ++i) {
			if (str.startsWith(word, i)) {
				if (i > 0) {
					ends += str.substring(i - 1, i);
					System.out.println("end is--->"+ends);
				}
				if(i + word.length() < str.length()) {//here i changed condition as i>0 not if(i + word.length() < str.length())
					ends += str.substring(i + word.length(), i + word.length() + 1);
					System.out.println("end isss--->"+ends);
				}
			}
		}
		return ends;
	}

}

Select allOpen in new window

above passed that test
end isss--->1
end is--->13
is--->13

wordEnds("XY123XY", "XY"));

wordEnds("abcXY123XYijk", "XY")

what is difference between above two. why first one failed with if (i > 0) { at bottom if loop?

if(i + word.length() < str.length()

what is meaning of above line?

It allows
ends += str.substring(i + word.length(), i + word.length() + 1);
to executed only when str.substring(i + word.length(), i + word.length() + 1) exists

http://www.tutorialspoint.com/java/java_string_startswith.htm

i see you are using method with offset

public class WordEnds {

      public static void main(String[] args) {
            // TODO Auto-generated method stub

            /*
             * Given a string and a non-empty word string, return a string made of
             * each char just before and just after every appearance of the word in
             * the string. Ignore cases where there is no char before or after the
             * word, and a char may be included twice if it is between two words.
             *
             * wordEnds("abcXY123XYijk", "XY") → "c13i" wordEnds("XY123XY", "XY") →
             * "13" wordEnds("XY1XY", "XY") → "11"
             */
            System.out.println("is--->" + wordEnds("abc1xyz1i1j", "1"));// abcXY123XYijk

      }

      public static String wordEnds(String str, String word) {
              String ends="";
              for( int i=0; i<str.length(); i++ ){
                 if( str.startsWith(word,i) ){
                   if( i>0 ){
                      ends += str.substring(i-1,i);
                   }
                   if( i+word.length()<str.length() ){
                       ends += str.substring(i+word.length(),i+word.length()+1);
                   }
                 }
              }
              return ends;
            }

}

above gave same output as below even after changing ++i to i++

public class WordEnds {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		/*
		 * Given a string and a non-empty word string, return a string made of
		 * each char just before and just after every appearance of the word in
		 * the string. Ignore cases where there is no char before or after the
		 * word, and a char may be included twice if it is between two words.
		 * 
		 * wordEnds("abcXY123XYijk", "XY") → "c13i" wordEnds("XY123XY", "XY") →
		 * "13" wordEnds("XY1XY", "XY") → "11"
		 */
		System.out.println("is--->" + wordEnds("abc1xyz1i1j", "1"));// abcXY123XYijk

	}

	public static String wordEnds(String str, String word) {
		  String ends="";
		  for( int i=0; i<str.length(); i++ ){
		     if( str.startsWith(word,i) ){
		       if( i>0 ){
		          ends += str.substring(i-1,i);
		       }
		       if( i+word.length()<str.length() ){
		           ends += str.substring(i+word.length(),i+word.length()+1);
		       }
		     }
		  }
		  return ends;
		}

}

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is--->cxziij


can i use i++ instead of ++i .

please advise

public class WordEnds {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		/*
		 * Given a string and a non-empty word string, return a string made of
		 * each char just before and just after every appearance of the word in
		 * the string. Ignore cases where there is no char before or after the
		 * word, and a char may be included twice if it is between two words.
		 * 
		 * wordEnds("abcXY123XYijk", "XY") → "c13i" wordEnds("XY123XY", "XY") →
		 * "13" wordEnds("XY1XY", "XY") → "11"
		 */
		System.out.println("is--->" + wordEnds("abc1xyz1i1j", "1"));// abcXY123XYijk

	}

	public static String wordEnds(String str, String word) {
		  String ends="";
		  for( int i=0; i<str.length(); i++ ){
		     if( str.startsWith(word,i) ){
		       if( i>0 ){
		          ends += str.substring(i-1,i);
		       }
		       if( i+word.length()<str.length() ){//3+1<11
		           ends += str.substring(i+word.length(),i+word.length()+1);//3+1,3+1+1
		       }
		     }
		  }
		  return ends;
		}

}

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above fails below
Expected      Run            
wordEnds("abcXY123XYijk", "XY") → "c13i"      "c13i"      OK         
wordEnds("XY123XY", "XY") → "13"      "13"      OK         
wordEnds("XY1XY", "XY") → "11"      "11"      OK         
wordEnds("XYXY", "XY") → "XY"      "XY"      OK         
wordEnds("XY", "XY") → ""      ""      OK         
wordEnds("Hi", "XY") → ""      ""      OK         
wordEnds("", "XY") → ""      ""      OK         
wordEnds("abc1xyz1i1j", "1") → "cxziij"      ""      X         
wordEnds("abc1xyz1", "1") → "cxz"      ""      X         
wordEnds("abc1xyz11", "1") → "cxz11"      ""      X         
wordEnds("abc1xyz1abc", "abc") → "11"      ""      X         
wordEnds("abc1xyz1abc", "b") → "acac"      ""      X         
wordEnds("abc1abc1abc", "abc") → "1111"      ""      X         
other tests
X         
Your progress graph for this problem

It allows
ends += str.substring(i + word.length(), i + word.length() + 1);
to executed only when str.substring(i + word.length(), i + word.length() + 1) exists

when str.substring(i + word.length(), i + word.length() + 1) does not exist?

when str.substring(i + word.length(), i + word.length() + 1) does not exist, trying to access it would cause java.lang.StringIndexOutOfBoundsException

It mean by does not exist?

What would "XY".substring(3,4) be?

"XY".substring(3,4) be?  means stringoutofbound exception as after index1 no more characters in the string xy

str.substring(i+word.length(),i+word.length()+1)

i see str or xy length if greater than i+word.length(),i+word.length()+1 ie 3,4 for example then only we cando substring..

can i use i++ instead of ++i .
Does it make any difference here?
please advise.

i++ instead of ++i makes no difference between
for( int i=0; i<str.length(); i++ ){
and
for( int i=0; i<str.length(); ++i ){

i++ instead of ++i makes no difference between
for( int i=0; i<str.length(); i++ ){
and
for( int i=0; i<str.length(); ++i ){

just here or any where?

When the resulting value is not used.

When the resulting value is not used.

here we are using i within if condition right?

The value of i is used in i<str.length();
The value of i++ is not used.