Coding Bat Java String 1 solutions 19 to 25

This post contains the solutions to Java String-1 section of codingbat.com for problems 19 to 25. If you are new here, you can check my previous post learn-coding-computer-programming-for-beginners. Solutions to problems 1 to 18 are available in the link java-string1-part-1.Solutions to previous sections are also available check the links to java-warmup-1 , java-warmup-2.

19.       Problem Name : middleThree 

Solution:

Hint: Given a string of odd length, return the string length 3 from its middle, so "Candy" yields "and".

Constraint: The string length will be at least 3. 

public String middleThree(String str)        {                 int len=str.length();                 if(len>3)                 {                 int middle=len/2;                 return(str.substring(middle-1,middle+2));                 }                 else                  return str;        }

20.       Problem Name : hasBad 

Solution:

Hint: Given a string, return true if "bad" appears starting at index 0 or 1 in the string, such as with "badxxx" or "xbadxx" but not "xxbadxx". Note: use .equals() to compare 2 strings. 

Constraint: The string may be any length, including 0

public boolean hasBad(String str)        {                                 int len=str.length();                 if(len>3)                 {                 if(str.substring(0,3).equals("bad")||str.substring(1,4).equals("bad"))                 return true;                 else                 return false;                 }                 else if(len==3)                 {                 if(str.substring(0,3).equals("bad"))                 return true;                 else                 return false;                 }                 else                 return false;                        }

21.       Problem Name : atFirst 

Solution:

Hint: Given a string, return a string length 2 made of its first 2 chars.

Constraint: If the string length is less than 2, use '@' for the missing chars

public String atFirst(String str)        {                 if(str.length()>2)                        return (str.substring(0,2));                 else                 {                        switch(str.length())                        {                        case 0:return("@@");                                             case 1:return(str.substring(0,str.length())+"@");                                             case 2:return (str.substring(0,str.length()));                                          default:return("");                        }                 }        }

22.       Problem Name : lastChars

Solution:

Hint: Given 2 strings, a and b, return a new string made of the first char of a and the last char of b, so "yo" and "java" yields "ya".

Constraint: If either string is length 0, use '@' for its missing char. 

public String lastChars(String a, String b)        {                 if(a.length()>1 && b.length()>1)                 {                        return(a.substring(0,1)+b.substring(b.length()-1,b.length()));                 }                 else                 {                        if(a.length()==0 && b.length()==0)                              return "@@";                        else if(a.length()==0)                              return("@"+b.substring(b.length()-1,b.length()));                        else                              return(a.substring(0,1)+(b.length()<1?"@":b.substring(b.length()-1,b.length())));                 }        }

23.       Problem Name : conCat

Solution:

Hint: Given two strings, append them together (known as "concatenation") and return the result.

Constraint: However, if the concatenation creates a double-char, then omit one of the chars, so "abc" and "cat" yields "abcat"

public String conCat(String a, String b)        {               if(a.length()>=1 && b.length()>=1)               {                 if(a.substring(a.length()-1,a.length()).equals(b.substring(0,1)))                        return (a.substring(0,a.length())+b.substring(1,b.length()));                 else                        return (a.substring(0,a.length())+b.substring(0,b.length()));                }                else if(b.length()==0)                       return (a.substring(0,a.length()));                else                       return(b.substring(0,b.length()));                      }

24.       Problem Name : lastTwo

Solution:

Hint: Given a string of any length, return a new string where the last 2 chars, if present, are swapped, so "coding" yields "codign". 

public String lastTwo(String str)        {                 int len=str.length();                 if(len>2)                 {                        return (str.substring(0,len-2)+str.substring(len-1,len)+str.substring(len-2,len-1));                 }                 else if(len==2)                 {                        return(str.substring(1,str.length())+str.substring(0,str.length()-1)) ;                 }                 else                 {                        return str;                 }        }

25.       Problem Name : seeColor

Solution:

Hint: Given a string, if the string begins with "red" or "blue" return that color string, otherwise return the empty string.

public String seeColor(String str)        {               int len=str.length();                             if(len>=3)               {                 if(str.substring(0,3).equals("red"))                        return "red";                 else if(str.substring(0,3).equals("blu"))                 {                        if(len==3)                             return "";                        else                             return "blue";                 }                   else                       return "";               }               else               {                      return"";               }        }

Please check my posts for solutions to the remaining problems of Java String 1 section.