Develop Reference

Java String Shortener

The instructions for the assignment are:
In many methods of communication throughout the last century, from telegrams to SMS messages to tweets, there is a benefit to reducing message length: either the number of characters is limited or using more characters incurs extra cost. Your job in this assignment is to write a program which takes a message as a string and reduces the number of characters it uses in a set way.
The first thing your program will do is ask the user to type a message which will be stored as a String. If the message contains less than 10 characters the program should print “This doesn’t need shortening!” and finish.
Otherwise, the message should be immediately converted to lowercase as this will make processing much easier. The program should then create a string in which every vowel (a, e, i, o, and u) from the message is removed unless the vowel is at the very start of a word (i.e., it is preceded by a space or is the first letter of the message). The program should also remove every repeated non-vowel character (i.e., if a character appears several times in a row it should only appear once at that location).
Finally, the program should output the shortened message, the number of vowels removed, the number of repeated non-vowel characters removed, and how much shorter the shortened message is than the original message. The exact format in which the program should print this information is shown in the sample runs.
my code is:
import java.util.Scanner;
import java.lang.Math;
class Main {
public static void main(String[] args)
{
Scanner scan = new Scanner(System.in);
System.out.println("Type the message to be shortened");
String message = scan.nextLine();
int messagelength = message.length();
String shortmsg = "";
int vowel = 0;
if (messagelength < 10)
{
System.out.print("\nThis doesn't need shortening!");
}
else
{
message = message.toLowerCase();
for(int i = 0; i < message.length(); i++)
{
if (i == 0)
{
shortmsg = "" + message.substring(0,1);
}
else
{
if(message.charAt(i - 1) != ' '){
if (
message.charAt(i) != 'a' &&
message.charAt(i) != 'e' &&
message.charAt(i) != 'o' &&
message.charAt(i) != 'u' &&
message.charAt(i) != 'i')
{
shortmsg += message.charAt(i);
}
else
{
vowel++;
}
}}
}
System.out.println("Shortened message: " + shortmsg);
System.out.println("Vowels removed: " + vowel);
System.out.println("Total characters saved: " + vowel);
}}}
when I put in "Please shorten this message" the output is "Shortened message: pls hrtn hs ssg"
I have been working on this assignment for days and I am failing the class because of it can someone please guide me to the correct answer.
Thanks for your help.

import java.util.Scanner;
import java.lang.Math;
class Main{
public static void main (String str[]){
Scanner scan = new Scanner(System.in);
System.out.println("Type the message to be shortened.");
String message = scan.nextLine();
int messageLength = message.length();
int messageVowels = 0;
String newMessage = "";
int repeat = 0;
int total = 0;
if (messageLength < 10) {
System.out.println("This doesn't need shortening!");
} else {
message = message.toLowerCase();
newMessage = newMessage + message.charAt(0);
for (int i = 1; i < messageLength; i++) {
if (message.charAt(i)== 'a' ||
message.charAt(i)== 'e' ||
message.charAt(i)== 'i' ||
message.charAt(i)== 'o' ||
message.charAt(i)== 'u') {
if (message.charAt(i-1) == ' '){
newMessage = newMessage + message.charAt(i);
}
else {
messageVowels++;
}
} else {
if (message.charAt(i) != message.charAt(i-1)) {
newMessage = newMessage + message.charAt(i);
}
else {
repeat++;
}
}
}
total = repeat + messageVowels;
System.out.println("Shortened message: " + newMessage);
System.out.println("Repeated letters removed: " + repeat);
System.out.println("Vowels removed: " + messageVowels);
System.out.println("Total characters saved: " + total);
}
}
}

guessing letters in a randomized word and printing a progress result to the User. Cannot figure out how [Java]

I am currently trying to right a rough draft code block for an object oriented hangman assignment I have to tackle. I know that similar questions have been asked but I didn't find a solution for the specific way i'm attempting to write this (which quite possibly is actual shite).
The way the code is intended to work is as follows.
Word_to_guess pulls a word from the array wordBank[] which contains 19 different fruits and 1 pickle (this is just to entertain my professor).
Then, the following While loop checks if "noSuccess" has been falsified, while it remains true the loop asks for character input from the user as a guess.
then the nested for loop iterates through the length of word_to_guess to check if Characters at index i match character c which has been set to userGuess.charAt(0) (in case the user enters more than 1 letter restricting their guess to the first letter in the string they might enter).
now this is where I'm having my issues. I don't know how to use the .replace method to fill in spots with specific characters and store newWord for each iteration of the for loop and have it print a progress report to the user as they guess so that they can keep track of their guesses. I had attempted to use the following statement
newWord = newWord.replace(newWord.CharAt(i), c) but this did not work and caused a compiling error stating that the index could not be found. Which i didn't understand and still don't.
the final if statement checks if noSuccess has been falsified which is defined by booleancheck.contentEquals(word_to_guess)
booleancheck is defined by newWord without any spaces between characters.
If anyone can lend me a hand in sorting out that portion of the code or any other parts that look iffy I'd greatly appreciate it.
Thank you so much!
Alex
word_to_guess = wordBank[num];
boolean noSuccess = true;
while(noSuccess)
{
System.out.println("Enter your guess: ");
System.out.println("letters used - " + lettersUsed);
userGuess = keyboard.nextLine();
c = userGuess.charAt(0);
for(int i = 0; i < word_to_guess.length(); i++)
{
if(word_to_guess.charAt(i) == c)
{
if(newWord.charAt(i) == ' ')
{
newWord = newWord.replace(' ', c);
}
else if(newWord.charAt(i) == '_')
{
newWord = newWord.replace('_', c);
}
}
else
newWord = newWord.replace(' ', '_');
}
System.out.println(newWord);
counter ++;
lettersUsed = lettersUsed + c;
System.out.println("letters used - " + lettersUsed);
String booleanCheck = newWord.replaceAll("\\s+","");
if(booleanCheck.contentEquals(word_to_guess ) && counter > 1)
{
noSuccess = false;
System.out.println("Great job, you guessed the right letters!");
}
Update #1:
I came up with the following code:
for(int i = 0; i < word_to_guess.length(); i++)
{
if(word_to_guess.charAt(i) == c)
{
strProg.setCharAt(i, c);
}
else
{
strProg.setCharAt(i, '_');
}
newWord = strProg.toString();
}
but i'm not sure what I'm doing wrong with the .toString() method because each iteration replaces the previous progress with "_" instead of being additive.
Update: #2
Edit to the previous update, I read that using StringBuilder in this instance is better than StringBuffer. I also discovered that the append and insert methods are available to the StringBuilder object.
This string object is located outside of the while loop the for loop is in.
String newWord = String.join("", Collections.nCopies(word_to_guess.length(),
" "));
this is inside the while loop.
StringBuilder strProg = new StringBuilder(newWord);
for(int i = 0; i < word_to_guess.length(); i++)
{
if(word_to_guess.charAt(i) == c)
{
strProg.insert(i, c);
}
else if(word_to_guess.charAt(i) != c && newWord.charAt(i) == '_')
{
strProg.delete(i, i);
}
else
{
strProg.insert(i, '_');
}
}
the .insert method is resulting in a much longer string. I don't know what to do now.

//The bugs was on replace method: I used a naive way to fix it
//Maybe you need also to check your initialization ...
public void hangman(){
String word_to_guess = "pickle";//wordBank[num];
boolean noSuccess = true;
//start: initializations
char c;
String lettersUsed = "";
String userGuess;
Scanner keyboard = new Scanner(System.in);
int counter=0;
//end: initializations
String newWord = word_to_guess.replaceAll("(?s).", " ");
while(noSuccess)
{
System.out.println("Enter your guess: ");
System.out.println("letters used: " + lettersUsed);
userGuess = keyboard.nextLine();
//sanity check: To ignore empty entry
if(userGuess.isEmpty())
continue;
c = userGuess.charAt(0);
for(int i = 0; i < word_to_guess.length(); i++)
{
if(word_to_guess.charAt(i) == c)
{
if(newWord.charAt(i) == ' ')
{
newWord = newWord.substring(0,i) + c + newWord.substring(i+1); //newWord = newWord.replace(' ', c);
}
else if(newWord.charAt(i) == '_')
{
newWord = newWord.substring(0,i) + c + newWord.substring(i+1);//newWord.replace('_', c);
}
}
else
newWord = newWord.replace(' ', '_');
}
System.out.println("New Word: "+newWord);
counter ++;
lettersUsed = lettersUsed + c;
System.out.println("letters used: " + lettersUsed);
String booleanCheck = newWord.replaceAll("\\s+","");
System.out.println("Check: "+booleanCheck);
if(booleanCheck.contentEquals(word_to_guess ) && counter > 1)
{
noSuccess = false;
System.out.println("Great job, you guessed the right letters!");
}
}
}

Counting vowels in a string and wrong output?

I am very new to java and I was wondering if you could help me out. Here is my code:
public static void main(String[] args) {
int vowels = 0;
Scanner input = new Scanner(System.in);
System.out.println ("Enter a string: ");
String string = input.nextLine();
int length = string.length();
for (int i = 0; i <= length; i++) {
String letter = string.substring(i, ++i);
if (letter.equalsIgnoreCase("a")){vowels++;}
if (letter.equalsIgnoreCase("e")){vowels++;}
if (letter.equalsIgnoreCase("i")){vowels++;}
if (letter.equalsIgnoreCase("o")){vowels++;}
if (letter.equalsIgnoreCase("u")){vowels++;}
}
System.out.println ("The number of vowels in " + string + " is: " + vowels);
}
The number is off but I can't figure out why.

This here is wrong
string.substring(i, ++i)
because the variable i is already incremented in the for-loop
so you are basically skipping chars in the string
implement the right logic, use the right data type
int length = string.length();
for (int i = 0; i < length; i++) {
char letter = string.charAt(i);
System.out.println(letter);
if (letter == 'a') {
vowels++;
} else if (letter == 'e') {
vowels++;
} else if (letter == 'i') {
vowels++;
} else if (letter == 'o') {
vowels++;
} else if (letter == 'u') {
vowels++;
}
}

Here is another solution you could try:
The split method will split the string into a String array. Then in your for loop it will check every item in your array.
public static void main(String[] args) {
int vowels = 0;
Scanner input = new Scanner(System.in);
System.out.println ("Enter a string: ");
String string = input.nextLine();
int length = string.length();
String[] stringArray = string.split("");
for (int i = 0; i < length; i++) { //I took out the = sign in your for loop arguments.
if (stringArray[i].equalsIgnoreCase("a")){vowels++;}
if (stringArray[i].equalsIgnoreCase("e")){vowels++;}
if (stringArray[i].equalsIgnoreCase("i")){vowels++;}
if (stringArray[i].equalsIgnoreCase("o")){vowels++;}
if (stringArray[i].equalsIgnoreCase("u")){vowels++;}
}
System.out.println ("The number of vowels in " + string + " is: " + vowels);
}

So I have this code here, it calculates the vowels in a given phrase. I'm trying to get it to repeat if the user says yes

I was wondering as to how I could get the end of the program to repeat if the user does respond with a 1. Do I need to reorganize it so that it is part of the if statement?
Scanner input = new Scanner(System.in);
System.out.println("Count Vowels \n============");
System.out.println("Type a sentence and this program will tell you\n\nhow many vowels there are (excluding 'y'):");
String string1;
string1 = input.nextLine();
string1 = string1.toLowerCase();
int vowels = 0;
int answer;
int i = 0;
for (String Vowels : string1.split(" ")) {
for (i = 0; i < Vowels.length(); i++) {
int letter = Vowels.charAt(i);
if (letter == 'a' || letter == 'e' || letter == 'i' || letter == 'o' || letter == 'u') {
vowels++;
}
}
System.out.println(Vowels.substring(0, 1).toUpperCase() + Vowels.substring(1) + " has " + vowels + " vowels");
vowels = 1;
}
System.out.println("Would you like to check another phrase in the Vowel Counter? if so Press 1 if not press 2");
answer = input.nextInt();
if (answer == 1) {
System.out.println("You have chosen to count the vowels in another phrase");
} else {
System.out.println("Have a nice day");
}

You can do this with a do/while loop. The skeleton for this kind of loop looks like this:
Scanner input = new Scanner(System.in);
do {
// do your stuff here
System.out.println("Would you like to check another phrase in the Vowel Counter? if so Press 1 if not press 2");
} while(input.nextInt() == 1);
System.out.println("Have a nice day");
It asks the user and evaluates the entered number in the while(input.nextInt() == 1) statement. If this comparison returns true (i.e. user entered 1), then the loops starts again. If not (i.e. user entered something else than 1), the loop stops and you'll get the "Good Bye" message instead.

you can split this up into more than one method and using one primary method call other methods inside a while loop. for example:
boolean continueCounting = false;
void countingVowels() {
//some start game method to make continueCounting = true
//something like "press 1 to start"
//if (input == 1) { continueCounting = true; }
while(continueCounting) {
String userInput = getUserInput();
countVowels(userInput); //count vowels in word from user input and prints them out to console
getPlayAgainDecision(); //ask user to put 1 or 2
if (answer == 1) {
continue
} else if (answer == 2) {
continueCounting = false;
} else {
System.out.println("incorrect input, please choose 1 or 2");
}
}
}

There are many ways to do this. A search on Google would have lead you to the correct answer in less time than it took you to ask the question. However, since you took the time to ask the question here is the answer:
import java.util.Scanner;
public class Driver {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
int answer = 0;
System.out.println("Count Vowels \n============");
// the do-while loop ensures that the code is executed at least once
do {
// on the first run answer equals zero, but on other runs it will equal one
if(answer == 1) {
System.out.println("You have chosen to count the vowels in another phrase");
}
System.out.println("Type a sentence and this program will tell you\n\nhow many vowels there are (excluding 'y'):");
String string1;
string1 = input.nextLine();
string1 = string1.toLowerCase();
int vowels = 0;
int i = 0;
for (String Vowels : string1.split(" ")) {
for (i = 0; i < Vowels.length(); i++) {
int letter = Vowels.charAt(i);
if (letter == 'a' || letter == 'e' || letter == 'i'
|| letter == 'o' || letter == 'u') {
vowels++;
}
}
System.out.println(Vowels.substring(0, 1).toUpperCase()
+ Vowels.substring(1) + " has " + vowels + " vowels");
vowels = 1;
}
System.out.println("Would you like to check another phrase in the Vowel Counter? If so type 1 if not type 2 and press enter");
answer = input.nextInt();
} while (answer == 1);
System.out.println("Have a nice day");
}
}
In your code you assert that a letter is a vowel if it is in the set a, e, i, o and u which is true. However, the letter y can be a vowel in certain situations.
In general, the Y is a consonant when the syllable already has a vowel. Also, the Y is considered a consonant when it is used in place of the soft J sound, such as in the name Yolanda or Yoda.
In the names Bryan and Wyatt, the Y is a vowel, because it provides the only vowel sound for the first syllable of both names. For both of these names, the letter A is part of the second syllable, and therefore does not influence the nature of the Y.
You could expand on your code even more by checking if the letter y is a vowel or not.

This is a more elegant way to do the counting (I updated the code to satisfy Johnny's comment that my previous answer didn't answer OP's question. The code now loops without unnecessary code):
public static void main(String... args)
{
int answer = 0;
Scanner input = null;
do
{
input = new Scanner(System.in);
System.out.print("Type a sentence and this program will tell you\nhow many vowels there are (excluding 'y'):");
String sentence = input.nextLine();
int vowels = 0;
String temp = sentence.toUpperCase();
for (int i = 0; i < sentence.length(); i++)
{
switch((char)temp.charAt(i))
{
case 'A':
case 'E':
case 'I':
case 'O':
case 'U':
vowels++;
}
}
System.out.println("The sentence: \"" + sentence + "\" has " + vowels + " vowels");
System.out.print("Would you like to check another phrase in the Vowel Counter? if so Press 1 if not press any other key... ");
String tempNum = input.next();
try
{
answer = Integer.parseInt(tempNum);
} catch (NumberFormatException e)
{
answer = 0;
}
System.out.println();
} while (answer == 1);
input.close();
System.out.println("Have a nice day");
}
Notice that at the end, I catch a NumberFormatException for more robustness validation of the user's input.

Just put the main for loop inside a do-while loop, like so:
do
{
for (String Vowels : string1.split(" ")) {
for (i = 0; i < Vowels.length(); i++) {
int letter = Vowels.charAt(i);
if (letter == 'a' || letter == 'e' || letter == 'i' || letter == 'o' || letter == 'u') {
vowels++;
}
}
System.out.println(Vowels.substring(0, 1).toUpperCase() +
Vowels.substring(1) + " has " + vowels + " vowels");
vowels = 1;
System.out.println("Would you like to check another phrase in the Vowel Counter? if so Press 1 if not press 2");
answer = input.nextInt();
}
} while (answer == 1);
System.out.println("Have a nice day");
Additionally, there are better ways to do the counting, for example:
for (char c : string1.toCharArray())
{
c = Character.toLowerCase(c);
if (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u')
count++;
}

String index out of bounds? (Java, substring loop)

This program I'm making for a COSC course isn't compiling right, I keep getting the error:
Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 2
at java.lang.String.substring(String.java:1765)
at VowelCount.main(VowelCount.java:13)
Here's my code:
import java.util.Scanner;
public class VowelCount {
public static void main(String[] args) {
int a = 0, e = 0, i = 0, o = 0, u = 0, count = 0;
String input, letter;
Scanner scan = new Scanner (System.in);
System.out.println ("Please enter a string: ");
input = scan.nextLine();
while (count <= input.length() ) {
letter = input.substring(count, (count + 1));
if (letter == "a") {
a++; }
if (letter == "e") {
e++; }
if (letter == "i") {
i++; }
if (letter == "o") {
o++; }
if (letter == "u") {
u++; }
count++;
}
System.out.println ("There are " + a + " a's.");
System.out.println ("There are " + e + " e's.");
System.out.println ("There are " + i + " i's.");
System.out.println ("There are " + o + " o's.");
System.out.println ("There are " + u + " u's.");
}
}
To my knowledge this should work, but why doesn't it? Any help would be great. Thank you!

You may need to take out the = in the line
while (count <= input.length() ) {
and make it
while (count < input.length() ) {
because it is causing the substring to read beyond the length of the string.
===============
But I'll add a few extra bits of advice even though its not asked for:
do not use == to compare strings, use
letter.equals("a")
instead. Or even better, try using
char c = input.charAt(count);
to get the current character then compare like this:
c == 'a'

I think your loop condition should be count < input.length. Right now, the last iteration runs with count == length, so your substring call is given a start index after the last character in the string, which is illegal. These type of boundary errors are very common when writing such loops, so it's always good to double- and triple-check your loop conditions when you encounter a bug like this.
Also, comparing strings with the == operator usually won't do what you want. That compares whether or not the two variables reference the same object. Instead, you want to test string1.equals(string2), which compares the contents of the two strings.

Removing the equal sign should fix that.
while (count < input.length()) {
and since you want to get a single character, you should do this:
substr(count,1)
because the 2nd parameter is actually length, not index.

Fixed it with help from everyone, and especially Vincent. Thank you! Runs wonderfully.
import java.util.Scanner;
public class VowelCount {
public static void main(String[] args) {
int a = 0, e = 0, i = 0, o = 0, u = 0, count = 0;
String input;
char letter;
Scanner scan = new Scanner (System.in);
System.out.print ("Please enter a string: ");
input = scan.nextLine();
while (count < input.length() ) {
letter = input.charAt (count);
if (letter == 'a')
a++;
if (letter == 'e')
e++;
if (letter == 'i')
i++;
if (letter == 'o')
o++;
if (letter == 'u')
u++;
count++;
}
System.out.println ("There are " + a + " a's.");
System.out.println ("There are " + e + " e's.");
System.out.println ("There are " + i + " i's.");
System.out.println ("There are " + o + " o's.");
System.out.println ("There are " + u + " u's.");
}
}

Before loop,try below
if(input.length()>0){
//you code
}