string example issue

Hi,

I am trying below challenge

http://codingbat.com/prob/p199720

I did not understand challenge itself to proceed further. please advise


Given a string, return a string made of the first 2 chars (if present), however include first char only if it is 'o' and include the second only if it is 'z', so "ozymandias" yields "oz".

startOz("ozymandias") → "oz"
startOz("bzoo") → "z"
startOz("oxx") → "o"
LVL 7
gudii9Asked:
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zzynxConnect With a Mentor Software engineerCommented:
>> I did not understand challenge itself to proceed further. please advise
>> Given a string, return a string made of the first 2 chars (if present),
>> however include first char only if it is 'o' and include the second only if it is 'z', so "ozymandias" yields "oz".

So basically they want you to return the string consisting of the first two characters of the given String.
But there's an extra condition for both characters. The first must be an 'o' and the second a 'z'.

Here's one of the many possible solutions:

public String startOz(String str) {
  String result = "";
  
  if (str.length()>0) { // does the given string contain at least one character?
     if (str.startsWith("o")) { // does the given string start with an "o"?
        result = result + "o";
     }
     str = str.substring(1); // chop off the first character of the given string
  }
  
  if (str.length()>0 && str.startsWith("z")) { // does the (chopped off) given string contain yet another character and is it a "z"?
    result = result + "z";
  }
  
  return result; 
}

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PS.
The above code of dpearson is just what is given on http://codingbat.com/prob/p199720.
I wonder how that does help?
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dpearsonConnect With a Mentor Commented:
It's rather a weird problem.  But it's asking you to check the first character of the string and only return it if it's an 'o'.  Then check the second character and only return that if it's a 'z'.

Here's a possible approach to solving it.  See if you can figure out how it works.  For instance, why do we check the str.length()?  Maybe you can find another way to write it?

public String startOz(String str) {
  String result = "" ;
  if (str.length() > 0 && str.charAt(0) == 'o') {
     result += "o" ;
  }
  if (str.length() > 1 && str.charAt(1) == 'z') {
     result += "z" ;
  }
  return result;
}

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Doug
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gudii9Author Commented:
what happens if i pass

startOz("z")  

also
startOz(" z")

also
startOz("bz")
please advise
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dpearsonCommented:
startOz("z") should return "" (z is not in the 2nd position)
startOz(" z") should return "z" (z is in the 2nd position)
startOz("bz") should return "z" (z is in the 2nd position)

Doug
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gudii9Author Commented:
public class Test7 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		String test=startOz("z"); //should return "" (z is not in the 2nd position)
	System.out.println("test is-->"+test);
	String test2=startOz(" z");
	System.out.println("test is-->"+test);
	String test3=startOz("dz");
	System.out.println("test is-->"+test);
	}

	
	public static String startOz(String str) {
		  String result = "";
		  
		  if (str.length()>0) { // does the given string contain at least one character?
		     if (str.startsWith("o")) { // does the given string start with an "o"?
		        result = result + "o";
		     }
		     str = str.substring(1); // chop off the first character of the given string
		  }
		  
		  if (str.length()>0 && str.startsWith("z")) { // does the (chopped off) given string contain yet another character and is it a "z"?
		    result = result + "z";
		  }
		  
		  return result; 
		}
}

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I ran above code

I got output different as below

test is-->
test is-->
test is-->

Please advise
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gudii9Author Commented:
public class Test7 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		String test=startOz("z"); //should return "" (z is not in the 2nd position)
	System.out.println("test is-->"+test);
	String test2=startOz(" z");
	System.out.println("test is-->"+test);
	String test3=startOz("dz");
	System.out.println("test is-->"+test);
	}

	
	public static String startOz(String str) {
		  String result = "" ;
		  if (str.length() > 0 && str.charAt(0) == 'o') {
		     result += "o" ;
		  }
		  if (str.length() > 1 && str.charAt(1) == 'z') {
		     result += "z" ;
		  }
		  return result;
		}
}

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I even tried above code and got similar output
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gudii9Author Commented:
public class Test8 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		String test=startOz("z"); //should return "" (z is not in the 2nd position)
	System.out.println("test is-->"+test);
	String test2=startOz(" z");
	System.out.println("test is-->"+test2);
	String test3=startOz("dz");
	System.out.println("test is-->"+test3);
	}

	
	public static String startOz(String str) {
		  String result = "";
		  
		  if (str.length()>0) { // does the given string contain at least one character?
		     if (str.startsWith("o")) { // does the given string start with an "o"?
		        result = result + "o";
		     }
		     str = str.substring(1); // chop off the first character of the given string
		  }
		  
		  if (str.length()>0 && str.startsWith("z")) { // does the (chopped off) given string contain yet another character and is it a "z"?
		    result = result + "z";
		  }
		  
		  return result; 
		}
}

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i think i forgot to change test2, test3 in sysout
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