We Keep Coding

Implementing While loop so my code repeats itself properly

In my code:
public static String input() {
Scanner input = new Scanner(System.in);
while(true) {
int qcount = 0;
String key = input.nextLine();
char[] keyCharArray = key.toCharArray();
for (int i = 0; i<keyCharArray.length;i++) {
//Here the while loop is supposed to break
if(keyCharArray[i]=='q') {
qcount++;
break;
}
}
int[] radie = new int[(keyCharArray.length)/2];
int[] höjd = new int[(keyCharArray.length)/2];
int counter = 0;
for(int i = 0; i < keyCharArray.length; i++){
if(i % 2 == 0){
radie[i/2] = keyCharArray[i] - '0';
}
else if(i % 2 != 0){
höjd[i/2] = keyCharArray[i] - '0';
}
}
for(int i = 0; i < (keyCharArray.length)/2; i++) {
System.out.print("r = " + radie[i] + " " + "h = " + höjd[i] + "\n\r" + "Basytans area: " + area(radie[i], höjd[i]) + "\n\r" + "Mantelytans area:" + area(radie[i]) + "\n\r" + "Volym: " + volume(radie[i], höjd[i]) + "\n\r");
}
return key;
}
}
The While loop is supposed to repeat the content until keyCharArray[i] =='q' -> There after the while loop is supposed to break
How can I make this work? Thanks
I have tried everything, yet I can't seem to solve it.
Appreciate any efforts, Thanks alot
Tried everything, doesn't work
sadasd
dsadsa
sdadsa
asdsda

You current code is (partially) like this:
public static String input(){
Scanner input = new Scanner(System.in);
while(true){
int qcount = 0;
String key = input.nextLine();
char[] keyCharArray = key.toCharArray();
for (int i = 0; i<keyCharArray.length;i++) {
if(keyCharArray[i]=='q') {
qcount++;
break;
}
}
// The rest...
}
}
The problem with this is that the break only breaks the inner for loop.
The simplest solution is to use the qcount variable you already have, and after the for loop check if it's non-zero to break out of the while loop:
for (int i = 0; i<keyCharArray.length;i++) {
if(keyCharArray[i]=='q') {
qcount++;
break;
}
}
if (qcount > 0) {
break; // Breaks out of the while loop
}
As for my suggestion in the comment it would be something like this instead:
private boolean shouldBreak(String key) {
char[] keyCharArray = key.toCharArray();
for (int i = 0; i<keyCharArray.length;i++) {
if(keyCharArray[i]=='q') {
return true; // Return that we should break the while loop
}
}
return false; // Do not break the while loop
}
public static String input(){
Scanner input = new Scanner(System.in);
while(true){
String key = input.nextLine();
if (shouldBreak(key)) {
break; // Breaks out of the while loop
}
// The rest...
}
}
I personally recommend something like this, as it makes the code cleaner and easier to read and understand and maintain.

Java remove parts from a words

Hello I can't make this work, I am given a main word followed by another sub words if the word is contained in the main word the part should be deleted.
//Example
//fmrog (in.nextLine)(main word)
//4 (in.nextInt)(the amount of sub words)
//roc(in.nextLine)(not contained)
//gor(in.nextLine)(not contained)
//rog(in.nextLine)(contained)
//ogr(in.nextLine)(not contained)
//result:fm
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
StringBuilder mainWord = new StringBuilder(in.nextLine);
int n = in.nextInt();
StringBuilder MainWord2 = new StringBuilder(mainWord);
in.nextLine();
for (int i = 0; i < n; i++) {
String subWord = in.nextLine();
int chars = subWord.length();
if (chars> mainWord.length()){
continue;
}
for (int j = 0; j < subWord.length(); j++) {
int r = 0;
for (int k = 0; k < mainWord.length(); k++) {
r++;
if (k > MainWord2.length() - 1) {
break;
}
if (MainWord2.charAt(k) == subWord.charAt(j)) {
break;
}
}
if (r <= MainWord2.length() && MainWord2.charAt(r-1) == subWord.charAt(j)) {
MainWord2.deleteCharAt(r - 1);
if (j >= subWord.length() -1 ) {
mainWord = MainWord2;
break;
}
}
if (r > MainWord2.length()) {
MainWord2 = mainWord;
break;
}
}
}
System.out.println(mainWord);
}
}
Honestly I am stucked maybe there is an easier way to solve this. The main thing is that when I write a case like : "super 2 pe surr" At the end at "surr" the two StringBuilders start to act as one when I delete chatAt at one of them the other one changes also

No need to make it so complex.
String input = // complete user input
String[] words = String.split(input);
String mainWord = words[0];
int numWords = Integer.parseInt(words[1]); // this variable isn't needed
for(int i = 2; i < words.length; i++) {
if (mainWord contains words[i]) {
mainWord = mainWord.replace(words[i], ""); // remove subword from mainword
}
}
At the end, mainWord will be the original mainWord without any subwords that were entered later.

public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int n = in.nextInt();
in.nextLine();
String[] words = new String[n];
for (int i = 0; i <n ; i++) {
words[i] = in.nextLine();
}
String mainWord = words[0];
for (int i = 1; i <words.length ; i++) {
if (mainWord.contains(words[i])){
mainWord = mainWord.replace(words[i], "");
}
}
System.out.println(mainWord);
}
}
Here but the thing is if the letters are not one next to another it doesnt remove the subword.

Compression algorithm in java

My goal is to write a program that compresses a string, for example:
input: hellooopppppp!
output:he2l3o6p!
Here is the code I have so far, but there are errors.
When I have the input: hellooo
my code outputs: hel2l3o
instead of: he213o
the 2 is being printed in the wrong spot, but I cannot figure out how to fix this.
Also, with an input of: hello
my code outputs: hel2l
instead of: he2lo
It skips the last letter in this case all together, and the 2 is also in the wrong place, an error from my first example.
Any help is much appreciated. Thanks so much!
public class compressionTime
{
public static void main(String [] args)
{
System.out.println ("Enter a string");
//read in user input
String userString = IO.readString();
//store length of string
int length = userString.length();
System.out.println(length);
int count;
String result = "";
for (int i=1; i<=length; i++)
{
char a = userString.charAt(i-1);
count = 1;
if (i-2 >= 0)
{
while (i<=length && userString.charAt(i-1) == userString.charAt(i-2))
{
count++;
i++;
}
System.out.print(count);
}
if (count==1)
result = result.concat(Character.toString(a));
else
result = result.concat(Integer.toString(count).concat(Character.toString(a)));
}
IO.outputStringAnswer(result);
}
}

I would
count from 0 as that is how indexes work in Java. Your code will be simpler.
would compare the current char to the next one. This will avoid printing the first character.
wouldn't compress ll as 2l as it is no smaller. Only sequences of at least 3 will help.
try to detect if a number 3 to 9 has been used and at least print an error.
use the debugger to step through the code to understand what it is doing and why it doesn't do what you think it should.

I am doing it this way. Very simple:
public static void compressString (String string) {
StringBuffer stringBuffer = new StringBuffer();
for (int i = 0; i < string.length(); i++) {
int count = 1;
while (i + 1 < string.length()
&& string.charAt(i) == string.charAt(i + 1)) {
count++;
i++;
}
if (count > 1) {
stringBuffer.append(count);
}
stringBuffer.append(string.charAt(i));
}
System.out.println("Compressed string: " + stringBuffer);
}

You can accomplish this using a nested for loops and do something simial to:
count = 0;
String results = "";
for(int i=0;i<userString.length();){
char begin = userString.charAt(i);
//System.out.println("begin is: "+begin);
for(int j=i+1; j<userString.length();j++){
char next = userString.charAt(j);
//System.out.println("next is: "+next);
if(begin == next){
count++;
}
else{
System.out.println("Breaking");
break;
}
}
i+= count+1;
if(count>0){
String add = begin + "";
int tempcount = count +1;
results+= tempcount + add;
}
else{
results+= begin;
}
count=0;
}
System.out.println(results);
I tested this output with Hello and the result was He2lo
also tested with hellooopppppp result he2l3o6p

If you don't understand how this works, you should learn regular expressions.
public String rleEncodeString(String in) {
StringBuilder out = new StringBuilder();
Pattern p = Pattern.compile("((\\w)\\2*)");
Matcher m = p.matcher(in);
while(m.find()) {
if(m.group(1).length() > 1) {
out.append(m.group(1).length());
}
out.append(m.group(2));
}
return out.toString();
}

Try something like this:
public static void main(String[] args) {
System.out.println("Enter a string:");
Scanner IO = new Scanner(System.in);
// read in user input
String userString = IO.nextLine() + "-";
int length = userString.length();
int count = 0;
String result = "";
char new_char;
for (int i = 0; i < length; i++) {
new_char = userString.charAt(i);
count++;
if (new_char != userString.charAt(i + 1)) {
if (count != 1) {
result = result.concat(Integer.toString(count + 1));
}
result = result.concat(Character.toString(new_char));
count = 0;
}
if (userString.charAt(i + 1) == '-')
break;
}
System.out.println(result);
}

The problem is that your code checks if the previous letter, not the next, is the same as the current.
Your for loops basically goes through each letter in the string, and if it is the same as the previous letter, it figures out how many of that letter there is and puts that number into the result string. However, for a word like "hello", it will check 'e' and 'l' (and notice that they are preceded by 'h' and 'e', receptively) and think that there is no repeat. It will then get to the next 'l', and then see that it is the same as the previous letter. It will put '2' in the result, but too late, resulting in "hel2l" instead of "he2lo".
To clean up and fix your code, I recommend the following to replace your for loop:
int count = 1;
String result = "";
for(int i=0;i<length;i++) {
if(i < userString.length()-1 && userString.charAt(i) == userString.charAt(i+1))
count++;
else {
if(count == 1)
result += userString.charAt(i);
else {
result = result + count + userString.charAt(i);
count = 1;
}
}
}
Comment if you need me to explain some of the changes. Some are necessary, others optional.

Here is the solution for the problem with better time complexity:
public static void compressString (String string) {
LinkedHashSet<String> charMap = new LinkedHashSet<String>();
HashMap<String, Integer> countMap = new HashMap<String, Integer>();
int count;
String key;
for (int i = 0; i < string.length(); i++) {
key = new String(string.charAt(i) + "");
charMap.add(key);
if(countMap.containsKey(key)) {
count = countMap.get(key);
countMap.put(key, count + 1);
}
else {
countMap.put(key, 1);
}
}
Iterator<String> iterator = charMap.iterator();
String resultStr = "";
while (iterator.hasNext()) {
key = iterator.next();
count = countMap.get(key);
if(count > 1) {
resultStr = resultStr + count + key;
}
else{
resultStr = resultStr + key;
}
}
System.out.println(resultStr);
}

Playfair Cipher, keep getting an excetption

I have the following code, but keep getting an error but the file builds ok, Im fairly new at all this.
Like I said the file builds ok, it accepts the inputs 1 & 2 and gives the options but keeps giving me an exception. It will ask for the keyword, and the plaintext but when it goes to decrypt or encrpt the error below appears.
Sorry about my first attempt at a queston.. Hopefully this is a bit better...
Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 3 at
java.lang.String.charAt(String.java:695) at
playfair.format(playfair.java:123) at
playfair.Divid2Pairs(playfair.java:135) at
playfair.Encript(playfair.java:187) at
playfair.main(playfair.java:332)
import java.util.Scanner;
public class playfair {
private String KeyWord=new String();
private String Key=new String();
private char matrix_arr[][]= new char[5][5];
public void setKey(String k){
// This function will take the input key from the user
// Then it'll remove duplication of letters from the key
// Will add it to the private KeyWord for matrix generation
String K_adjust=new String();
boolean flag = false;
K_adjust = K_adjust + k.charAt(0);
for(int i=1; i<k.length();i++){
for(int j=0;j<K_adjust.length(); j++){
if(k.charAt(i)==K_adjust.charAt(j))
{
flag = true;
}
}
if(flag == false){
K_adjust = K_adjust + k.charAt(i);
}
flag = false;
}
KeyWord=K_adjust;
}
public void KeyGen()
{
// This function adjust the alphabetical letters adding the
// KeyWord on the beginning of them & then it calls the matrix function
boolean flag=true;
char current;
Key=KeyWord;
for ( int i=0 ; i<26 ; i++){
current=(char)(i+97);
if(current=='j')
continue;
for(int j=0 ; j< KeyWord.length() ; j++ ){
if (current == KeyWord.charAt(j)){
flag=false;
break;
}
}
if(flag)
Key=Key+current;
flag=true;
}
System.out.println(Key);
matrix ();
}
private void matrix ()
{
int counter=0;
for (int i=0 ; i<5 ;i++){
for (int j=0 ; j<5 ; j++){
matrix_arr[i][j]=Key.charAt(counter);
System.out.printf("%s ",matrix_arr[i][j]);
counter++;
}
System.out.println("\n");
}
}
private String format(String old_text)
{
// This function is to adjust the Text to encrypt
// It changes all the 'j' letters to 'i' & add 'x' character
// between repeatable pairs.
int i = 0;
int j = 0;
int len = 0;
String text = new String();
len = old_text.length();
//System.out.println(old_text);
/*** Change all j's into i's *****/
for (int tmp = 0; tmp < len; tmp++)
{
if (old_text.charAt(tmp) == 'j')
{
text = text + 'i';
}
else
text = text+old_text.charAt(tmp);
}
/**********************************/
len = text.length();
/*** Assign 'x' to letters that repeat in a diagram ***/
for (i = 0; i < len; i = i + 2){ //run for half of string length
if (text.charAt(i+1) == text.charAt(i)){ //if char = previous char
text = text.substring(0, i+1) + 'x' + text.substring(i+1);
}else{ //not a repeat character, move along
}
}
return text;
}
private String [] Divid2Pairs (String new_string)
{
String Original = format(new_string);
int size= Original.length();
if(size%2!=0){
size++;
Original = Original+'x';
}
String x[]= new String[size/2];
int counter=0;
for ( int i=0 ; i<size/2 ;i++){
x[i]=Original.substring(counter, counter+2);
System.out.println(x[i]);
counter=counter+2;
}
return x;
}
public int[] GetDiminsions(char letter){
int []key=new int[2];
if ( letter == 'j')
letter='i';
for (int i=0 ; i<5 ;i++)
{
for (int j=0 ; j<5 ; j++){
if(matrix_arr[i][j] == letter){
key[0]=i;
key[1]=j;
break;
}
}
}
return key;
}
public String Encript(String Source)
{
System.out.println("Encription Start");
String src_arr[]=Divid2Pairs(Source);
String Code=new String();
char one;
char two;
int part1[]=new int[2];
int part2[]=new int[2];
//start on pair by pair
for (int i=0 ; i< src_arr.length ;i++ ){
one = src_arr[i].charAt(0);//get first char
two = src_arr[i].charAt(1);//get second char
part1 = GetDiminsions(one);//get position of the first char
part2 = GetDiminsions(two);//get position of the second char
//check for special cases
if(part1[0]==part2[0]){//same row
if (part1[1]<4)
part1[1]++;
else
part1[1]=0;
if(part2[1]<4)
part2[1]++;
else
part2[1]=0;
}
else if (part1[1]==part2[1]) //same column
{
if (part1[0]<4)
part1[0]++;
else
part1[0]=0;
if(part2[0]<4)
part2[0]++;
else
part2[0]=0;
}
else
{
int temp=part1[1];
part1[1]=part2[1];
part2[1]=temp;
}
Code= Code + matrix_arr[part1[0]][part1[1]] + matrix_arr[part2[0]][part2[1]];
}
System.out.println(Code);
return Code;
}
public String Decript (String Code){
System.out.println("Decription Start");
String Original=new String();
String src_arr[]=Divid2Pairs(Code);
char one;
char two;
int part1[]=new int[2];
int part2[]=new int[2];
//start on pair by pair
for (int i=0 ; i< src_arr.length ;i++ ){
one = src_arr[i].charAt(0);//get first char
two = src_arr[i].charAt(1);//get second char
part1 = GetDiminsions(one);//get position of the first char
part2 = GetDiminsions(two);//get position of the second char
//check for special cases
if(part1[0]==part2[0]){//same row
if (part1[1]>0)
part1[1]--;
else
part1[1]=4;
if(part2[1]>0)
part2[1]--;
else
part2[1]=4;
}
else if (part1[1]==part2[1]) //same column
{
if (part1[0]>0)
part1[0]--;
else
part1[0]=4;
if(part2[0]>0)
part2[0]--;
else
part2[0]=4;
}
else
{
int temp=part1[1];
part1[1]=part2[1];
part2[1]=temp;
}
Original =Original + matrix_arr[part1[0]][part1[1]] + matrix_arr[part2[0]][part2[1]];
}
System.out.println(Original);
return Original;
}
/**
* #param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
playfair x=new playfair();
Scanner sc = new Scanner(System.in);
System.out.println("Enter a lower case keyword:");
String keyword = sc.next();
x.setKey(keyword);
x.KeyGen();
System.out.println("To Encrypt enter 1 \nTo Decript enter 2\nTesting both enter anything else:");
int choosen_value = sc.nextInt();
if(choosen_value==1)
{
System.out.println("Enter a lower case word to encrypt:");
String key_input = sc.next();
String Encripted= x.Encript(key_input);
}else if(choosen_value==2){
System.out.println("Enter a lower case word to decrypt:");
String decripted = sc.next();
x.Decript(decripted);
}else{
System.out.println("Enter a lower case word to encrypt & decrypt:");
String key_input = sc.next();
String Encripted= x.Encript(key_input);
x.Decript(Encripted);
}
}
}
Again Many thanks in advance

In the format method, in the below loop
for (i = 0; i < len; i = i + 2)
text.charAt(i+1) is the line causing the problem.
You need to traverse till the len-1 instead of len.
This is because when i is exactly 1 than len, it'd still execute the for loop, but i+1 in the charAt() method will try to fetch the char present at the index len(since i+1 is now equal to len), which throws the StringIndexOutOfBoundsException as the maximum accessible index in a String is str.length()-1.

(i = 0; i < len; i = i + 2) is causing exception
you might need to do i<len-1 here.

changing 'invisible' chaaracters to letters, game of hangman

so in my program im trying to incorporate a couple of different classse into my main program which i am coming up with the code.
What i am given
Dictionary() {
dictionary = new String[NUMBER_OF_WORDS];
Scanner inputStream = null;
try {
inputStream = new Scanner(new File(FILE_NAME));
}catch (FileNotFoundException e) {
System.out.println("Dictionary class cannot find file \"dictionaryData.txt\".");
System.out.println("Please make sure that the file is in the project folder.");
System.exit(0);
}
for (int i = 0; i < NUMBER_OF_WORDS; i++) {
dictionary[i] = inputStream.next();
}
}
public String getRandomWord(){
Random generator = new Random();
String temp = new String();
temp += dictionary[generator.nextInt(NUMBER_OF_WORDS)];
return temp;
}
public boolean find(String word) {
int count = 0;
int lowerIndex = 0;
int upperIndex = NUMBER_OF_WORDS - 1;
int middleIndex;
while(lowerIndex <= upperIndex){
middleIndex = (lowerIndex + upperIndex) / 2;
count++;
if(word.equalsIgnoreCase(dictionary[middleIndex])) { // found it
return true;
}
else if (word.compareToIgnoreCase(dictionary[middleIndex]) < 0) { // word smaller than middle
upperIndex = middleIndex - 1;
}
else { // word is larger than middle
lowerIndex = middleIndex + 1;
}
}
return false;
}
}
along with another class WordHider
WordHider() {
secretWord = new String();
wordMask = new String();
}
public String getWordMask() {
return wordMask;
}
public String getSecretWord() {
return secretWord;
}
public void setSecretWord(String newSecretWord) {
secretWord = newSecretWord.toLowerCase();
if (secretWord.length() > 0) {
wordMask = HIDE_CHAR;
for (int i = 1; i < secretWord.length(); i++) {
wordMask += HIDE_CHAR;
}
}
}
public boolean isHiddenWordFound() {
for (int i = 0; i < wordMask.length(); i++) {
if(wordMask.charAt(i) == HIDE_CHAR.charAt(0)) {
return false;
}
}
return true;
}
public int revealLetter(String letter) {
int count = 0;
String newFoundWord = "";
if (letter.length() == 1) {
for (int i = 0; i < secretWord.length(); i++) {
if ((secretWord.charAt(i) == letter.charAt(0))
&& (wordMask.charAt(i) == HIDE_CHAR.charAt(0))) {
count++;
newFoundWord += letter;
}
else {
newFoundWord += wordMask.charAt(i);
}
}
}
wordMask = newFoundWord;
return count;
}
}
and using those classes i have to come up with code that looks like this:
Word: ********** Guesses Left: 5
Enter your guess: a
Miss!
Word: ********** Guesses Left: 4
Enter your guess: e
Miss!
Word: ********** Guesses Left: 3
Enter your guess: i
Word: i**i*i**** Guesses Left: 3
Enter your guess: o
Word: i**i*i*o** Guesses Left: 3
And ive got a couple of questions about this,
1) i have a dictionaryData.text that i was given and have to implement
that into my code. it contains a list of 81thousand words and im not
sure how to have my program recognize its there. Dictionary class
cannot find file "dictionaryData.txt". Please make sure that the file
is in the project folder. ^ i get that error when i try and print a
random word
2) How do i get my program to change the letters of a word to
stars(Hide the word)
3) put it all in a loop?

Parts of the Dictionary class and the WordHider class are missing. Nevertheless, I'll try and answer your questions.
1) Like I said, you're missing part of the Dictionary class. You incorporate the class like this:
Dictionary dictionary = new Dictionary();
String word = dictionary.getRandomWord();
2) Like this:
wordHider.setSecretWord(word);
3) I'm not sure what "it" is, but yes, your user has to guess a letter. Then you have to check to see if the letter is in the word. Like this:
wordHider.revealLetter(letter);
Then you have to display the word and let the user guess another letter. This guess / check / display has to be in a loop.