So i'm trying to reverse a sentence and even though I don't have any errors when compiling, it tells me my reverse sentence is out of bounds.
-It should work like this: "hello, world!" --> !dlrow ,olleh"
Said code:
String sentence="this is a sentence!";
String reverseSentence=sentence;
for(int counter=0;counter<sentence.length();counter++)
{
char charToReplace,replaceChar;
charToReplace = reverseSentence.charAt(counter);
replaceChar = sentence.charAt(sentence.length()-counter);
reverseSentence=reverseSentence.replace(charToReplace, replaceChar);
System.out.println(reverseSentence);
}
The reason for the exception you are getting is that in sentence.charAt(sentence.length()-counter), sentence.length()-counter is out of bounds when counter is 0. Should be sentence.length()-1-counter.
However, as Tunaki commented, there are other problems with your code. I suggest you use a StringBuilder to construct the reversed String, instead of using replace (which would replace any occurrence of the first character with the second character).
You can use character arrays to implement your requirement like this,
String sentence = "ABDEF";
char[] firstString = sentence.toCharArray();
char[] reversedString = new char[sentence.length()];
for (int counter = 0; counter < sentence.length(); counter++) {
reversedString[counter] = firstString[sentence.length() - counter -1];
}
System.out.println(String.copyValueOf(reversedString));
It doesn't show you an error because the Exception concerning the indexes happen at RunTime.
Here :
replaceChar = sentence.charAt(sentence.length()-counter);
You're trying to access index 19 of your String (19-0). Replace it with :
replaceChar = sentence.charAt(sentence.length()-counter-1);
I'd recommend to use a StringBuilder in your situation though.
Either use the reverse() method :
String sentence = "this is a sentence!";
String reversed = new StringBuilder(sentence).reverse().toString();
System.out.println(reversed); // Prints : !ecnetnes a si siht
Or use the append() method for building your new String object. This uses less memory than using a String because it is not creating a new String object each time you're looping :
String sentence = "this is a sentence!";
StringBuilder reversed = new StringBuilder();
for (int i = 0 ; i < sentence.length() ; i++){
reversed.append(sentence.charAt(sentence.length() - 1 - i));
}
System.out.println(reversed.toString()); // Prints : !ecnetnes a si siht
It maybe better to do it without any replacement, or for loop. It you create a char array from the string, reverse the array, then create a string from the reversed array this would do what you've asked without any moving parts or replacements. For example:
String hw = "hello world";
char[] hwChars = hw.toCharArray();
ArrayUtils.reverse(hwChars);
String wh = new String(hwChars);
System.out.println(wh);
Just split the String at each whitespace and put it in String array and then print the array in reverse order
public static void main(String[] args) {
String sentence = "this is a sentence!";
String[] reverseSentence = sentence.split(" ");
for (int i = reverseSentence.length-1; i >= 0; i--) {
System.out.print(" " + reverseSentence[i]);
}
}
Related
I've been trying for a while now, and I just give up. I want to extract the data from type (regardless whether it's a capital letter or not) to the numbers. Pretty much, I'm trying to get rid of model and birthday in each line, but what makes it even more difficult, is that it's all one string. I spaced it out just to make it easier to read.
I'm trying to find the answer in REGEX java. This is what I was trying but, is deleting of course the whole String after the first number(4,66)
[;][mo].*
Thank you in advance!
Input:
Type:Carro;high:4,66;model:fourDoors;birthday:01/01/1980
type:Truck;high:5,66;model:twoDoors;birthday:29/05/1977
tYpe:motorcycle;high:1,55;model:fiveDoors;birthday:01/01/1980
type:Carro;high:4,66;type:model;birthday:6/12/1887
type:Carro;high:9,66;model:Doors;birthday:05/12/2010
Expected OutPut:
Type:Carro;high:4,66
type:Truck;high:5,66
tYpe:motorcycle;high:1,55
type:Carro;high:4,66
type:Carro;high:9,66
Hopefully this will work for you. There are a few ways to make this code slightly smaller, however, this should at least help to get you on the right path.
I placed it into a main method, but it would be easy to put it into its own function. This would allow you to pass any number of arrays at it.
I added all of the logic in the comments within the code, I hope it helps:
public static void main(String[] args) {
/*Get your strings into an Array*/
String[] str = {"Type:Carro;high:4,66;model:fourDoors;birthday:01/01/1980",
"type:Truck;high:5,66;model:twoDoors;birthday:29/05/1977",
"tYpe:motorcycle;high:1,55;model:fiveDoors;birthday:01/01/1980",
"type:Carro;high:4,66;type:model;birthday:6/12/1887",
"type:Carro;high:9,66;model:Doors;birthday:05/12/2010",
"Expected OutPut:",
"Type:Carro;high:4,66",
"type:Truck;high:5,66",
"tYpe:motorcycle;high:1,55",
"type:Carro;high:4,66",
"type:Carro;high:9,66"
};
/*Create a "final staging" array*/
String[] newStr = new String[str.length - 1];
for (int j = 0; j < str.length - 1; j++) {//For each of your strings
str[j] = str[j].toLowerCase();//set the string to lower
/*If they don't contain a semi-colon and a model or birthday reference go to else*/
if (str[j].contains(";") && str[j].contains("model") || str[j].contains("birthday")) {
/*Otherwise, split the string by semi-colon*/
String[] sParts = str[j].split(";");
String newString = "";//the new string that will be created
for (int i = 0; i < sParts.length - 1; i++) {//for each part of the sParts array
if (sParts[i].contains("model") || sParts[i].contains("birthday")) {//if it contains what is not desired
//Do Nothing
} else {
newString += sParts[i];//otherwise concatenate it to the newString
}
newStr[j] = newString;//add the string to the "final staging" array
}
} else {
newStr[j] = str[j];//if it didn't have semi-colons and birthday or model, just add it to the "final staging" array
}
}
for (String newS : newStr) {// finally if you want to see the "final staging" array data... output it.
System.out.println(newS);
}
}
OUTPUT
type:carrohigh:4,66
type:truckhigh:5,66
type:motorcyclehigh:1,55
type:carrohigh:4,66
type:carrohigh:9,66
expected output:
type:carro;high:4,66
type:truck;high:5,66
type:motorcycle;high:1,55
type:carro;high:4,66
If I happened to miss something in the requirements, please let me know, I would be happy to fix it.
String str = "Type:Carro;high:4,66;model:fourDoors;birthday:01/01/1980,type:Truck;high:5,66;model:twoDoors;birthday:29/05/1977,tYpe:motorcycle;high:1,55;model:fiveDoors;birthday:01/01/1980,type:Carro;high:4,66;type:model;birthday:6/12/1887";
StringTokenizer tokens = new StringTokenizer(str, ",");
while (tokens.hasMoreTokens()) {
String token = tokens.nextToken() ;
StringTokenizer tokens2 = new StringTokenizer(token, ":");
while (tokens2.hasMoreTokens()) {
String key = tokens2.nextToken() ;
if (key.equalsIgnoreCase("type")){
System.out.println("locate: "+key+"\n");
}
}
}
how to remove "," in below string specified at s[0,2] location(818001,818002)(151515,151515) and store again to string []
String[] s = {"818001,818002","121212","151515,151515"};
You should explain more detailed your problem.
I think what you want is this:
s = '(818001,818002)(151515,151515)' //the string you have.
s = s.replace(')(',',').replace('(','').replace(')','');// output "818001,818002,151515,151515"
final_string = s.split(','); //output (4) ["818001", "818002", "151515", "151515"]
If you need to remove a comma (or any other char for that matter) in your String array indices the simplest is to iterate through the array and use String.replace():
String[] s = {"818001,818002","121212","151515,151515"};
for(int i=0; i<s.length; i++) {
s[i] = s[i].replace(",", "");
}
System.out.print(Arrays.toString(s)); // [818001818002, 121212, 151515151515]
I'm new to java and I wrote this method to input a string word and output the word spelled backwards. The intent is to create a method and not use an already existing method such as the simple reverse. Please help point me in the direction of how to do this to reverse a word. I'm also trying to determine/count if there are palindromes. Please help! I've read other questions and I can't find anything specific enough to my case. I know that my code doesn't run, though I'm unsure how to fix it to get the correct output.
An example would be the word "backwards" to go to "sdrawkcab".
public static int reverseWord(String word) {
int palindromes = 0;
for (int i = word.length(); i >= 0; i--) {
System.out.print(i);
word.equalsIgnoreCase();
if (word.charAt(i)) == index(word.charAt(0 && 1))) {
palindromes++
System.out.println(palindromes)
}
return i;
}
}
There are multiple problems with your code.
1.The prototype of equalsIgnoreCase is
public boolean equalsIgnoreCase(String str);
So this method expect a String to be passed,but your not not passing anything here.To fix this,pass another string with whom you want to match your word like this..
word.equalsIgnoreCase("myAnotherString");
2.word.charAt(i);
Suppose word="qwerty",so indexing of each character will be like this
/* q w e r t y
0 1 2 3 4 5 */
So when you use i = word.length();i will 6 since word is of length 6.So
word.charAt(i) will search for character at index 6,but since there is not index 6,it will return an exception ArrayIndexOutOfBound.To fix this,start i from word.length()-1.
3.if (word.charAt(i));
This extra " ) ".Remove it.
Is Index() your own method?.If Yes,then check that also.
the below code prints the reverse of the input string and checks if it is a palindrome
public static void main(String[] args) {
String input = "dad";
char temp[] = input.toCharArray();//converting it to a array so that each character can be compared to the original string
char output[] = new char[temp.length];//taking another array of the same size as the input string
for (int i = temp.length - 1, j = 0; i >= 0; i--, j++) {//i variable for iterating through the input string and j variable for inserting data into output string.
System.out.print(temp[i]);//printing each variable of the input string in reverse order.
output[j] = temp[i];//inserting data into output string
}
System.out.println(String.valueOf(output));
if (String.valueOf(output).equalsIgnoreCase(input)) {//comparing the output string with the input string for palindrome check
System.out.println("palindrome");
}
}
Because your question about what is wrong with your code was already answered here is another way you could do it by using some concepts which are somewhat less low level than directly working with character arrays
public static boolean printWordAndCheckIfPalindrome(final String word) {
// Create a StringBuilder which helps when building a string
final StringBuilder reversedWordBuilder = new StringBuilder("");
// Get a stream of the character values of the word
word.chars()
// Add each character to the beginning of the reversed word,
// example for "backwards": "b", "ab", "cab", "kcab", ...
.forEach(characterOfString -> reversedWordBuilder.insert(0, (char) characterOfString));
// Generate a String out of the contents of the StringBuilder
final String reversedWord = reversedWordBuilder.toString();
// print the reversed word
System.out.println(reversedWord);
// if the reversed word equals the given word it is a palindrome
return word.equals(reversedWord);
}
I tried to make a program that separates characters.
The question is:
"Create a char array and use an array initializer to initialize the array with the characters in the string 'Hi there'. Display the contents of the array using a for-statement. Separate each character in the array with a space".
The program I made:
String ini = "Hi there";
char[] array = new char[ini.length()];
for(int count=0;count<array.length;count++) {
System.out.print(" "+array[count]);
}
What should I do to fix this problem?
Here's how you convert a String to a char array:
String str = "someString";
char[] charArray = str.toCharArray();
I'd recommend that you use an IDE when programming, to easily see which methods a class contains (in this case you'd be able to find toCharArray()) and compile errors like the one you have above. You should also familiarize yourself with the documentation, which in this case would be this String documentation.
Also, always post which compile errors you're getting. In this case it was easy to spot, but when it isn't you won't be able to get any answers if you don't include it in the post.
you are doing it wrong, you have first split the string using space as a delimiter using String.split() and populate the char array with charcters.
or even simpler just use String.charAt() in the loop to populate array like below:
String ini="Hi there";
char[] array=new char[ini.length()];
for(int count=0;count<array.length;count++){
array[count] = ini.charAt(count);
System.out.print(" "+array[count]);
}
or one liner would be
String ini="Hi there";
char[] array=ini.toCharArray();
char array[] = new String("Hi there").toCharArray();
for(char c : array)
System.out.print(c + " ");
Here is the code
String str = "Hi There";
char[] arr = str.toCharArray();
for(int i=0;i<arr.length;i++)
System.out.print(" "+arr[i]);
Instead of above way u can achieve the solution simply by following method..
public static void main(String args[]) {
String ini = "Hi there";
for (int i = 0; i < ini.length(); i++) {
System.out.print(" " + ini.charAt(i));
}
}
You initialized and declared your String to "Hi there", initialized your char[] array with the correct size, and you began a loop over the length of the array which prints an empty string combined with a given element being looked at in the array. At which point did you factor in the functionality to put in the characters from the String into the array?
When you attempt to print each element in the array, you print an empty String, since you're adding 'nothing' to an empty String, and since there was no functionality to add in the characters from the input String to the array. You have everything around it correctly implemented, though. This is the code that should go after you initialize the array, but before the for-loop that iterates over the array to print out the elements.
for (int count = 0; count < ini.length(); count++) {
array[count] = ini.charAt(count);
}
It would be more efficient to just combine the for-loops to print each character out right after you put it into the array.
for (int count = 0; count < ini.length(); count++) {
array[count] = ini.charAt(count);
System.out.println(array[count]);
}
At this point, you're probably wondering why even put it in a char[] when I can just print them using the reference to the String object ini itself.
String ini = "Hi there";
for (int count = 0; count < ini.length(); count++) {
System.out.println(ini.charAt(count));
}
Definitely read about Java Strings. They're fascinating and work pretty well, in my opinion. Here's a decent link: https://www.javatpoint.com/java-string
String ini = "Hi there"; // stored in String constant pool
is stored differently in memory than
String ini = new String("Hi there"); // stored in heap memory and String constant pool
, which is stored differently than
char[] inichar = new char[]{"H", "i", " ", "t", "h", "e", "r", "e"};
String ini = new String(inichar); // converts from char array to string
.
Another easy way is that you use string literal and convert it to charArray in declaration itself.
Something like this -
char array[] = "Hi there".toCharArray();
//Print with white spaces
for(char c : array)
System.out.print(c + " ");
I wan to remove the last set of data from string using java.
For example I have a string like A,B,C, and I want to remove ,C, and want to get the out put value like A,B . How is it possible in java? Please help.
String start = "A,B,C,";
String result = start.subString(0, start.lastIndexOf(',', start.lastIndexOf(',') - 1));
Here is a fairly "robust" reg-exp solution:
Pattern p = Pattern.compile("((\\w,?)+),\\w+,?");
for (String test : new String[] {"A,B,C", "A,B", "A,B,C,",
"ABC,DEF,GHI,JKL"}) {
Matcher m = p.matcher(test);
if (m.matches())
System.out.println(m.group(1));
}
Output:
A,B
A
A,B
ABC,DEF,GHI
Since there may be a trailing comma, something like this (using org.apache.commons.lang.StringUtils):
ArrayList<String> list = new ArrayList(Arrays.asList(myString.split()));
list.remove(list.length-1);
myString = StringUtils.join(list, ",");
You can use String#lastIndexOf to find the index of the second-to-last comma, and then String#substring to extract just the part before it. Since your sample data ends with a ",", you'll need to use the version of String#lastIndexOf that accepts a starting point and have it skip the last character (e.g., feed in the string's length minus 1).
I wasn't going to post actual code on the theory better to teach a man to fish, but as everyone else is:
String data = "A,B,C,";
String shortened = data.substring(0, data.lastIndexOf(',', data.length() - 2));
You can use regex to do this
String start = "A,B,C,";
String result = start.replaceAll(",[^,]*,$", "");
System.out.println(result);
prints
A,B
This simply erases the the 'second last comma followed by data followed by last comma'
If full String.split() is not possible, the how about just scanning the string for comma and stop after reaching 2nd, without including it in final answer?
String start = "A,B";
StringBuilder result = new StringBuilder();
int count = 0;
for(char ch:start.toCharArray()) {
if(ch == ',') {
count++;
if(count==2) {
break;
}
}
result.append(ch);
}
System.out.println("Result = "+result.toString());
Simple trick, but should be efficient.
In case you want last set of data removed, irrespective of how much you want to read, then
start.substring(0, start.lastIndexOf(',', start.lastIndexOf(',')-1))
Another way to do this is using a StringTokenizer:
String input = "A,B,C,";
StringTokenizer tokenizer = new StringTokenizer(input, ",");
String output = new String();
int tokenCount = tokenizer.countTokens();
for (int i = 0; i < tokenCount - 1; i++) {
output += tokenizer.nextToken();
if (i < tokenCount - 1) {
output += ",";
}
}
public string RemoveLastSepratorFromString(string input)
{
string result = input;
if (result.Length > 1)
{
result = input.Remove(input.Length - 1, 1);
}
return result;
}
// use from above method
string test = "1,2,3,"
string strResult = RemoveLastSepratorFromString(test);
//output --> 1,2,3