Trying to write a code that makes a string become altcase (ie. "hello" becomes "HeLlO". I borrowed code from another question on this forum that asked for something similar (Java Case Switcher) However, the code only switched the casing of a letter instead of having a capital letter (first), then lowercase letter, etc. pattern.
What I have so far:
public String altCase(String text)
{
String str = "";
for (int i = 0; i <= text.length(); i++)
{
char cA = text.charAt(i);
if (text.charAt(0).isUppercase)
{
str += Character.toLowerCase(cA);
}
if (text.charAt(0).isLowercase)
{
str += Character.toUpperCase;
}
if(i != 0 && Character.isUpperCase(cA))
{
if (text.charAt(i)-1.isUpperCase || text.charAt(i)+1.isUpperCase)
{
str += Character.toLowerCase(cA);
}
else
{
str += cA;
}
}
if(i != 0 && Character.isLowerCase(cA))
{
if (text.charAt(i)-1.isLowerCase || text.charAt(i)+1.isLowerCase)
{
str += Character.toUpperCase(cA);
}
else
{
str += cA;
}
}
}
return str;
}
I'm still relatively new to coding in general so please excuse my inefficiencies, as well as any headaches I might induce from the lack of experience in my coding. I cannot tell where I am going wrong except maybe when I typed "text.charAt(i)-1.isLowerCase" as the statement seems a bit illogical, but I am lost in terms of trying to come up with something else that would accomplish the same thing. Or is my error completely elsewhere? Thanks for any help in advance.
The modulus operator could take you a long way here...
StringBuilder rslt = new StringBuilder();
for (int i = 0; i < text.length(); i++) {
char c = text.charAt(i);
switch (i % 2) {
case 0:
rslt.append(Character.toUpperCase(c));
break;
case 1:
rslt.append(Character.toLowerCase(c));
break;
}
}
return rslt.toString();
If I truly understand what you want to get is that:
Get a string, change it in a format of AbCdEfG.... and so on.
There is more simple solution.
Get a string and with for loop, for every character, change character size depending on position in string, for i%2 == 0 upper case, and i%2 == 1 lower case.
public String altCase(String text)
{
String str = "";
for (int i = 0; i < text.length(); i++)
{
char cA = text.charAt(i);
if (i%2 == 0)
{
str += Character.toUpperCase(cA);
}
else
{
str += Character.toLowerCase(cA);
}
}
return str;
}
I would start with a StringBuilder (a mutable character sequence) of text.toLowerCase(); then set the characters at even indices to their capital equivalents (and your method doesn't appear to depend on instance state, so it might be static). Something like,
public static String altCase(String text) {
StringBuilder sb = new StringBuilder(text.toLowerCase());
for (int i = 0; i < text.length(); i += 2) {
sb.setCharAt(i, Character.toUpperCase(sb.charAt(i)));
}
return sb.toString();
}
IntStream.range(0, s.length()).mapToObj(i -> i % 2 == 0 ?
Character.toUpperCase(s.charAt(i)) :
Character.toLowerCase(s.charAt(i)))
.map(String::valueOf)
.collect(Collectors.joining());
Related
So here's what I'm trying to do. I take a given string, and make a new string. The new string will be the same as the original string, but will have the consonants doubled.
For example, rabbit becomes rrabbitt and so forth. It only doubles the consonants that aren't already doubled.
Here's what I have so far:
// Returns a new string in which all consonants in the given string are doubled.
// Consonants that are already doubled are not doubled again.
// For example, doubleConsonants("rabbit") returns "rrabbitt".
// It is assumed that in the given string is alphabetic and that no character
// appears more than twice in a row.
// Parameters:
// s - given string
// Returns new string with all consonants doubled
----------------------------------------------------------------------------
public static String doubleConsonants(String s) {
String newString = "";
String vowels = "aeiouAEIOU";
for (int i = 0; i < s.length(); i++) {
boolean hasVowel = false;
for (int n = 0; n == 10; n++){
if ( vowels.charAt(n) == s.charAt(i)) {
newString += s.charAt(i);
i++;
hasVowel = true;
break;
}
}
if (hasVowel = false && s.charAt(i) != s.charAt(i+1) && s.charAt(i) != s.charAt(i-1)) {
newString += s.charAt(i);
i++;
}
else if (hasVowel = false) {
newString += s.charAt(i);
i++;
}
}
return newString;
}
Apparently there are some issues with "dead code" and the boolean hasVowels is "not used". What am I screwing up?
You can do one thing. Using a contains() method will greatly reduce all your work.
for (int i = 0; i < s.length(); i++) { // traverse through the string
if (i < s.length() - 1 && s.charAt(i) == s.charAt(i + 1)) {
newString += s.charAt(i); // handles the double constant special condition like bb in rabbit
i++;
} else if (vowels.contains("" + s.charAt(i))) { //check if the letter is a vowel
newString += s.charAt(i); // if yes, add it once
} else {
newString += "" + s.charAt(i) +s.charAt(i); // else add it twice
}
}
At the end of this code block, you will have the required string stored in newString. you can read more about contains()
Try this.
public static String doubleConsonants(String s) {
return s.replaceAll("(?i)(([^aeiou])\\2+)|([^aeiou])", "$1$3$3");
}
First thing I notice is that the if-statements towards the bottom are using the assignment operator. You want to use the double-equals to test the value. I'll have to look more closely at the logic for more.
I have this code that filters a String str, keeping only some chars, resulting in the reduced String fStr. The subtlety is that I only keep a target char, if it is not equal to the last char in fStr:
ArrayList<Character> targetChars = //{a, b, c};
String str = "axxbxxxxbxbxcxa", fStr = "";
for(int i = 0, s = 0 ; i < str.length() ; i++) {
char c = str.charAt(i);
if(targetChars.contains(c)) {
if(s > 0 && fStr.charAt(s-1) != c) {
fStr += c;
s++;
}
}
}
fStr → "abca"
In the innermost if statement, I have to include s > 0 before fStr.charAt(s-1) != c, otherwise the latter will throw an OutOfBounds exception the first time targetChars.contains(c) is true. But only the first time, it annoys me that the loop will always check that I won't be out of bounds, given that it only has to do it once. I know I could do something like that:
ArrayList<Character> targetChars = //{a, b, c};
String str = "auebskrubnbocpa", fStr = "";
int i = 0, s = 0;
for(; i < str.length() ; i++) {
char c = str.charAt(i);
if(targetChars.contains(c)) {
fStr += c;
s++;
i++;
break;
}
}
for(; i < str.length() ; i++) {
char c = str.charAt(i);
if(targetChars.contains(c)) {
if(fStr.charAt(s-1) != c) {
fStr += c;
s++;
}
}
}
But is there a more elegant and less annoying way to dynamically truncate a conditional statement?
Is there a way to dynamically change conditions in if statement in Java?
No there isn't. The original version of your code is the best from a readability perspective.
However, if you are concerned about efficiency, then you should be using a StringBuilder rather than fStr += c.
Also a char[] and an explicit for loop is likely to be faster than ArrayList<Character>.contains.
Here is how I would do it, but not sure if it suits your needs
public class Example {
public static void main(String[] args) {
char[] targetChars = {'a', 'b', 'c'};
String str = "axxbxxxxbxbxcxa", fStr = " ";
for(int i = 0 ; i < str.length() ; i++) {
char c = str.charAt(i);
if(isAcceptableChar(c, targetChars)) {
if(fStr.charAt(fStr.length() - 1) != c) {
fStr = fStr.trim() + c;
}
}
}
System.out.println(fStr);
}
private static boolean isAcceptableChar(char newChar, char[] targetChars) {
boolean value = false;
for(char ch : targetChars){
if(ch == newChar) {
value = true;
break;
}
}
return value;
}
}
Sure there is, just call a function that returns a boolean value that you use in your if condition. Different functions could be called at different times by using a function pointer.
I have a question regarding the problem at codingbat in String 3. Question is as follows:
Given a string, look for a mirror image (backwards) string at both the
beginning and end of the given string. In other words, zero or more
characters at the very begining of the given string, and at the very
end of the string in reverse order (possibly overlapping).
For example, the string "abXYZba" has the mirror end "ab"
mirrorEnds("abXYZba") → "ab"
mirrorEnds("abca") → "a"
mirrorEnds("aba") → "aba"
My code is as follows:
public String mirrorEnds(String string) {
if(string.length() <=1) return string;
String x = "";
int y = string.length() - 1;
for(int i = 0; i < string.length()/2; i++)
{
if(string.charAt(i) == string.charAt(y))
{
x+= Character.toString(x.charAt(i));
y--;
}
else
{
return x;
}
}
return string;
}
When I try it for the following:
"xxYxx"
String length is 5 so index from 0-4. If I run it on my code, the logic will be:
i = 0 and y = 4;
string.charAt(i) == string.charAt(y) //true and i++ and y--
string.charAt(i) == string.charAt(y) //true and i++ and y--
//i is == string.length()/2 at this point
But the problem throws me an error saying indexoutofbounds. Why is this the case?
You are accessing the ith character of the wrong string here:
x += Character.toString(x.charAt(i));
The String x is empty at first, so the character at index 0 doesn't exist.
Access the original string instead.
x += Character.toString(string.charAt(i));
Here my code for this problem , simple one
public String mirrorEnds(String string) {
int start = 0;
int end = string.length()-1;
for(int i=0;i<string.length();i++){
if(string.charAt(start) == string.charAt(end) ){
start++;
end--;
}
if(start != ((string.length()-1)-end)){
break;
}
}
return string.substring(0,start);
}
public String mirrorEnds(String string) {
String g="";
for(int i=0;i<string.length();i++){
if(string.charAt(i)==string.charAt(string.length()-1-i)){
g=g+string.charAt(i);
} else{
break;
}
}
return g;
}
You have a good start, but I think you should consider an even simpler approach. You only need to use one index (not both i and y) to keep track of where you are in the string because the question states that overlapping is possible. Therefore, you do not need to run your for loop until string.length() / 2, you can have it run for the entire length of the string.
Additionally, you should consider using a while loop because you have a clear exit condition within the problem: once the string at the beginning stops being equal to the string at the end, break the loop and return the length of the string. A while loop would also use less variables and would reduce the amount of conditional operators in your code.
Here's my answer to this problem.
public String mirrorEnds(String string) {
String mirror = "";
int i = 0;
while (i < string.length() && string.charAt(i) == string.charAt(string.length() - i - 1) {
mirror += string.charAt(i);
i++;
}
return mirror;
}
Another handy tip to note is that characters can be appended to strings in Java without casting. In your first if statement within your for loop, you don't need to cast x.charAt(i) to a string using Character.toString(), you can simply append x.charAt(i) to the end of the string by writing x += x.charAt(i).
public String mirrorEnds(String str) {
StringBuilder newStr = new StringBuilder();
String result = "";
for (int i=0; i <= str.length(); i++){
newStr.append(str.substring(0, i));
if (str.startsWith(newStr.toString()) && str.endsWith(newStr.reverse().toString()))
result = str.substring(0, i);
newStr.setLength(0);
}
return result;
}
public String mirrorEnds(String string) {
// reverse given string
String reversed = "";
for (int i = string.length() - 1; i >= 0; i--) {
reversed += string.charAt(i);
}
// loop through each string simultaneously. if substring of 'string' is equal to that of 'reversed',
// assign the substring to variable 'text'
String text = "";
for (int i = 0; i <= string.length(); i++) {
if (string.startsWith(string.substring(0, i)) ==
string.startsWith(reversed.substring(0, i))) {
text = string.substring(0, i);
}
}
return text;
}
public String mirrorEnds(String string) {
String out = "";
int len = string.length();
for(int i=0,j = len-1;i<len;i++,j--)
{
if(string.charAt(i) == string.charAt(j))
out += string.charAt(i);
else
break;
}
return out;
}
I have a String called "originalstring" which contains a sentence with mixed upper and lower case characters.
I simply want to flip the string so that if a character is a lowercase make it upper case and vice versa and return it.
I have tried this code, which returns the original string in upperCase:
for (int i = 0; i < originalString.length(); i++) {
char c = originalString.charAt(i);
if (Character.isUpperCase(c)) {
originalString += Character.toLowerCase(c);
}
if (Character.isLowerCase(c)) {
originalString += Character.toUpperCase(c);
}
}
return originalString;
You are adding characters to the original string. Also, this means that your for loop will never get to the end of the iteration of the for loop, because originalString.length() changes each loop also. It's an infinite loop.
Instead, create a StringBuilder that stores the converted characters as you're iterating over the original string. The convert it to a String and return it at the end.
StringBuilder buf = new StringBuilder(originalString.length());
for (int i = 0; i < originalString.length(); i++) {
char c = originalString.charAt(i);
if (Character.isUpperCase(c)) {
buf.append(Character.toLowerCase(c));
}
else if (Character.isLowerCase(c)) {
buf.append(Character.toUpperCase(c));
}
// Account for case: neither upper nor lower
else {
buf.append(c);
}
}
return buf.toString();
Common-lang provide a swapCase function, see the doc. Sample from the doc:
StringUtils.swapCase(null) = null
StringUtils.swapCase("") = ""
StringUtils.swapCase("The dog has a BONE") = "tHE DOG HAS A bone"
And if you really want to do it by yourself, you can check the source of common-lang StringUtils
Instead of using existing utilities, you may try below conversion using boolean operation:
To upper case:
char upperChar = (char) (c & 0x5f)
To lower case:
char lowerChar = (char) (c ^ 0x20)
In your program:
StringBuilder result = new StringBuilder(originalString.length());
for (int i = 0; i < originalString.length(); i++) {
char c = originalString.charAt(i);
if (Character.isUpperCase(c)) {
result.append((char) (c ^ 0x20));
}
else if ((c >= 'a') && (c <= 'z')) {
result.append((char) (c & 0x5f));
}
else {
result.append(c);
}
}
System.out.println(result);
Please help me to identify my mistakes in this code. I am new to Java. Excuse me if I have done any mistake. This is one of codingbat java questions. I am getting Timed Out error message for some inputs like "xxxyakyyyakzzz". For some inputs like "yakpak" and "pakyak" this code is working fine.
Question:
Suppose the string "yak" is unlucky. Given a string, return a version where all the "yak" are removed, but the "a" can be any char. The "yak" strings will not overlap.
public String stringYak(String str) {
String result = "";
int yakIndex = str.indexOf("yak");
if (yakIndex == -1)
return str; //there is no yak
//there is at least one yak
//if there are yaks store their indexes in the arraylist
ArrayList<Integer> yakArray = new ArrayList<Integer>();
int length = str.length();
yakIndex = 0;
while (yakIndex < length - 3) {
yakIndex = str.indexOf("yak", yakIndex);
yakArray.add(yakIndex);
yakIndex += 3;
}//all the yak indexes are stored in the arraylist
//iterate through the arraylist. skip the yaks and get non-yak substrings
for(int i = 0; i < length; i++) {
if (yakArray.contains(i))
i = i + 2;
else
result = result + str.charAt(i);
}
return result;
}
Shouldn't you be looking for any three character sequence starting with a 'y' and ending with a 'k'? Like so?
public static String stringYak(String str) {
char[] chars = (str != null) ? str.toCharArray()
: new char[] {};
StringBuilder sb = new StringBuilder();
for (int i = 0; i < chars.length; i++) {
if (chars[i] == 'y' && chars[i + 2] == 'k') { // if we have 'y' and two away is 'k'
// then it's unlucky...
i += 2;
continue; //skip the statement sb.append
} //do not append any pattern like y1k or yak etc
sb.append(chars[i]);
}
return sb.toString();
}
public static void main(String[] args) {
System.out.println(stringYak("1yik2yak3yuk4")); // Remove the "unlucky" strings
// The result will be 1234.
}
It looks like your programming assignment. You need to use regular expressions.
Look at http://www.vogella.com/articles/JavaRegularExpressions/article.html#regex for more information.
Remember, that you can not use contains. Your code maybe something like
result = str.removeall("y\wk")
you can try this
public static String stringYak(String str) {
for (int i = 0; i < str.length(); i++) {
if(str.charAt(i)=='y'){
str=str.replace("yak", "");
}
}
return str;
}