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Nested for loop, not picking up first instance in Array

I am trying to encode a word, and I am not sure why my for loops aren't picking up the first instance, 0. The input for this method is "This" and 3. The output from this method is klv. So my loop must not be working properly as the letter T is getting skipped. What is wrong with my loops?
String encodeWord(String word, int Shift) {
//word = "This"
//Shift = 3, is how far the letter is shifted to the right of the original
char[] alphabet = "abcdefghijklmnopqrstuvwxyz".toCharArray();
char[] temp = word.toCharArray();
char[] FA = new char[temp.length];
String tempWord = "";
StringBuilder sb = new StringBuilder(64);
for (int x = 0; x < word.length(); x++) {
for (int y = 0; y < alphabet.length; y++) {
if (word.charAt(0) == alphabet[y]) {
FA[0] = alphabet[y + shift];
System.out.println(FA[0]);
}
}
}
for (int i = 0; i < word.length(); i++) {
for (int j = 0; j < alphabet.length; j++) {
if (word.charAt(i) == alphabet[j]) {
FA[i] = alphabet[j + shift];
sb.append(FA[i]);
System.out.println(FA[i]);
}
}
}
System.out.println(sb);
return sb.toString();
}

The letter 'T' is different from the letter 't', so since only the letter 't' is found in your array, the program won't find a match for the letter 'T'.
Another problem with your code is that you will get an Index out of bounds exception if the input contains the letters 'x', 'y' or 'z' because there aren't 3 letters after them in the array.

public static String encoder(String word, int shift)
{
static const int max_char = 122; //letter 'z'
static const int min_char = 97; //letter 'a'
char[] c_array = word.toCharArray();
char[] encoded_string = new char[c_arary.length()];
for(for i = 0; i < c_array.length(); i++)
{
if( ((int)c + shift) > max_char) //makes sure that the ascii isnt a non number
{
encoded_string[i] = (min_char + (int)c + shift - max_char ); // this will correct the overflow
}
c = c + shfit;
}
return encoded_string;
}
This is an easier way to do this... also your loops have a few logical errors.. the first one i caught was in the first loop... if there is a z in your word your going to overflow your alphabet array.
This is using the Ascii table way

Changing every 5th character in a String java

I'm trying to get a function to take a String and change every 5th character to a 'z'. For whatever reason the first character changed is always the 6th character and I can't figure out why. There's also an error if the string is divisible by 5, which is either because it starts on the 6th character or because my loop iteration goes one too far.
I've messed with the loop iteration but just can't see why it's starting on the 6th character.
public static String change5thPosition(String s) {
int fives = (int) Math.floor((s.length() / 5));
System.out.println(fives);
char[] chars = s.toCharArray();
for (int i = 0; i <= fives; i++) {
if (i != 0)
chars[i * 5] = 'z';
}
String returnString = new String(chars);
return returnString;
}
Input example:
all mimsy were the baragroves
Expected output:
all zimsyzwerezthe zbragzoves
Actual output:
all mzmsy zere zhe bzragrzves
Edit: Thanks for the help. here is my updated code:
public static String change5thPosition(String s) {
char[] chars = s.toCharArray();
for (int i = 4; i < s.length(); i = i + 5) {
chars[i] = 'z';
}
String returnString = new String(chars);
return returnString;
}

Your code changes:
i=1 : chars[1 * 5 = 5]
i=2 : chars[2 * 5 = 10]
... and so on.
But since arrays are indexed starting with 0, you actually want to change the characters at 4,9,14, ....
So just subtract 1.
chars[i*5 - 1] = 'z';
These "off by one" errors are quite common in programming, and you'll learn to anticipate them.
On a side note, there's no need for:
for(int i=0; i<=fives; i++){
if (i!=0) {
...
}
}
... when you can just start i at 1:
for(int i=1; i<=fives; i++){
...
}
You could also avoid having to multiply, by incrementing in fives:
for(int i=4, i < chars.length; i += 5) {
char[i] = 'z';
}

Simply add a -1 to your index.
public static String change5thPosition(String s){
int fives = (int)Math.floor((s.length()/5));
System.out.println(fives);
char[] chars = s.toCharArray();
for(int i=0; i<=fives; i++){
if (i!=0)
chars[i*5 -1]='z';
}
String returnString = new String(chars);
return returnString;
}

A simple loop will do the Job. Take care of the index and avoid complex calculations.
String n = "all mimsy were the baragroves";
char[] s = n.toCharArray();
for(int i = 4;i<s.length;i+=5){
s[i]='z';
}
System.out.println(s);

You can try this code.
public class Simple {
public static void main(String args[]) {
System.out.println(change5thPosition("all mimsy were the baragroves"));
}
public static String change5thPosition(String s) {
int fives = (int) Math.floor((s.length() / 5));
System.out.println(fives);
char[] chars = s.toCharArray();
int index = 1;
StringBuilder myvar = new StringBuilder();
for (int i = 0; i < s.length(); i++) {
char c = s.charAt(i);
if (index == 5) {
myvar.append("z");
index = 1;
} else {
myvar.append(c);
index++;
}
}
return myvar.toString();
}
}

Java program to find the letter that appears in the most words?

I have a sentence, and I want to find the char that appears in the most words, and how many words it appears in.
For example: "I like visiting my friend Will, who lives in Orlando, Florida."
Which should output I 8.
This is my code:
char maxChar2 = '\0';
int maxCount2 = 1;
for (int j=0; j<strs2.length; j++) {
int charCount = 1;
char localChar = '\0';
for (int k=0; k<strs2[j].length(); k++) {
if (strs2[j].charAt(k) != ' ' && strs2[j].charAt(k) != maxChar2) {
for (int l=k+1; l<strs2[j].length(); l++) {
if (strs2[j].charAt(k)==strs2[j].charAt(l)) {
localChar = strs2[j].charAt(k);
charCount++;
}
}
}
}
if (charCount > maxCount2) {
maxCount2 = charCount;
maxChar2 = localChar;
}
}
, where strs2 is a String array.
My program is giving me O 79. Also, uppercase and lowercase do not matter and avoid all punctuation.

As a tip, try using more meaningful variable names and proper indentation. This will help a lot especially when your program is not doing what you thought it should do. Also starting smaller and writing some tests for it will help a bunch. Instead of a full sentence, get it working for 2 words, then 3 words, then a more elaborate sentence.
Rewriting your code to be a bit more readable:
// Where sentence is: "I like".split(" ");
private static void getMostFrequentLetter(String[] sentence) {
char mostFrequentLetter = '\0';
int mostFrequentLetterCount = 1;
for (String word : sentence) {
int charCount = 1;
char localChar = '\0';
for (int wordIndex = 0; wordIndex < word.length(); wordIndex++) {
char currentLetter = word.charAt(wordIndex);
if (currentLetter != ' ' && currentLetter != mostFrequentLetter) {
for (int l = wordIndex + 1; l < word.length(); l++) {
char nextLetter = word.charAt(l);
if (currentLetter == nextLetter) {
localChar = currentLetter;
charCount++;
}
}
}
}
if (charCount > mostFrequentLetterCount) {
mostFrequentLetterCount = charCount;
mostFrequentLetter = localChar;
}
}
}
Now all I did was rename your variables and change your for loop to a for-each loop. By doing this you can see more clearly your algorithm and what you're trying to do. Basically you're going through each word and comparing the current letter with the next letter to check for duplicates. If I run this with "I like" i should get i 2 but instead I get null char 1. You aren't properly comparing and saving common letters. This isn't giving you the answer, but I hope this makes it more clear what your code is doing so you can fix it.

Here is a somewhat more elegant solution
public static void FindMostPopularCharacter(String input)
{
String alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
input = input.toUpperCase();
HashMap<Character, Integer> charData = new HashMap<>();
char occursTheMost = 'A'; //start with default most popular char
int maxCount = 0;
//create the map to store counts of all the chars seen
for(int i = 0; i < alphabet.length(); i++)
charData.put(alphabet.charAt(i), 0);
//first find the character to look for
for(int i = 0; i < input.length(); i++)
{
char c = input.charAt(i);
//if contained in our map increment its count
if(charData.containsKey(c))
charData.put(c, charData.get(c) + 1);
//check for a max count and set the values accordingly
if(charData.containsKey(c) && charData.get(c) > maxCount)
{
occursTheMost = c;
maxCount = charData.get(c);
}
}
//final step
//now split it up into words and search which contain our most popular character
String[] words = input.split(" ");
int wordCount = 0;
CharSequence charSequence;
for(Character character : charData.keySet())
{
int tempCount = 0;
charSequence = "" + character;
for(int i = 0; i < words.length; i++)
{
if(words[i].contains(charSequence))
tempCount++;
}
if(tempCount > wordCount)
{
occursTheMost = character;
wordCount = tempCount;
}
}
System.out.println(occursTheMost + " " + wordCount);
}
Output of
String input = "I like visiting my friend Will, who lives in Orlando, Florida.";
FindMostPopularCharacter(input);
is
I 8
Note: If there are ties this will only output the character that first reaches the maximum number of occurrences.
FindMostPopularCharacter("aabb aabb aabb bbaa");
Outputs
B 4
because B reaches the max first before A due to the last word in the input.
FindMostPopularCharacter("aab aab b")
B 3

How would I splice and add these two char arrays?

I have this array.
char [] cornStrand = {'G','G','A','G','T','T','C','C','C','A'};
I also have this array, for which the values are inputted by the user running the program.
char [] bacteriaStrand = new char [5];
String strBases = scan.nextLine();
for (int s=0; s <bacteriaStrand.length; s++)
{
char c = strBases.charAt(s);
bacteriaStrand[s]= c ;
}
The second block of code essentially inputs the values that the user entered into the bacteria strand array.
Now comes the tricky part. I need to "splice" and combine both arrays. By this I mean:
If the first character of
char [] bacteriaStrand
is A, then I have to insert
char [] bacteriaStrand
After the first G in
char [] cornStrand
Now, after I splice this, I have to put what I spliced into a new array, called
char [] combinedStrand
This is where I am becoming confused. If anyone can help, please do so! I would gladly appreciate it!

Maybe do something like this:
public char[] combine(char[] bacteriaStrand, char[] cornStrand) {
char[] result = new char[bacteriaStrand.length + cornStrand.length];
if (bacteriaStrand[0] == 'A') {
for (int i = 0; i < cornStrand.length; i++) {
boolean insertedBacteria = false;
if (cornStrand[i] == 'G') {
insertedBacteria = true;
for (int j = 0; j < bacteriaStrand.length; j++) {
result[i + 1 + j] = bacteriaStrand[j];
}
if (insertedBacteria)
i += bacteriaStrand.length;
result[i] = cornStrand[i];
}
}
}
return result;
}

If that is the only rule, it seems pretty simple to do.
if (bacteriaStrand[0] == 'A') {
int totalLength = cornStrand.length + bacteriaStrand.length;
char [] combinedStrand = new char [totalLength];
for(int i=0; i<cornStrand.length; i++){
combinedStrand[i] = cornStrand[i]; //fill in corn until you find the first G
if (cornStrand[i] == 'G') {
int j = 0;
for(; j<bacteriaStrand.length; j++){
combinedStrand[i+j+1] = bacteriaStrand[j]; //fill in bacteria
}
i++;
for(;i<cornStrand.length;i++){
combinedStrand[i+j+1] = cornStrand[i] //fill in the rest of corn
}
}
}//now this loop will break, since you increased i, so you won't get duplicates
}

How do I find out the position of a char

I've got an String ("Dinosaur") and I don't exactly know how, but how do I get the position of the char "o" and is it in all possible to get two positions like if my String was ("Pool")

As for your first question, you can use String#indexOf(int) to get the index of every 'o' in your string.
int oPos = yourString.indexOf('o');
As for your second question, it is possible to get all positions of a given char by making a method which uses String.indexOf(int, int), tracking the previous index so that you don't repeat searched portions of the string. You could store the positions in an array or list.

Use indexOf with a loop:
String s = "Pool";
int idx = s.indexOf('o');
while (idx > -1) {
System.out.println(idx);
idx = s.indexOf('o', idx + 1);
}

Simply:
public static int[] getPositions(String word, char letter)
{
List<Integer> positions = new ArrayList<Integer>();
for(int i = 0; i < word.length(); i++) if(word.charAt(i) == letter) positions.add(i);
int[] result = new int[positions.size()];
for(int i = 0; i < positions.size(); i++) result[i] = positions.get(i);
return result;
}

This is probably going a little over board, but hey ;)
String master = "Pool";
String find = "o";
Pattern pattern = Pattern.compile(find);
Matcher matcher = pattern.matcher(master);
String match = null;
List<Integer[]> lstMatches = new ArrayList<Integer[]>(5);
while (matcher.find()) {
int startIndex = matcher.start();
int endIndex = matcher.end();
lstMatches.add(new Integer[] {startIndex, endIndex});
}
for (Integer[] indicies : lstMatches) {
System.out.println("Found " + find + " # " + indicies[0]);
}
Gives me
Found o # 1
Found o # 2
The great thing is, you could also find "oo" as well

Have you tried converting the String to a char array?
int counter = 0;
String input = "Pool";
for(char ch : input.toCharArray()) {
if(ch == 'o') {
System.out.println(counter);
}
counter += 1;
}

Try this
String s= "aloooha";
char array[] = s.toCharArray();
Stack stack = new Stack();
for (int i = 0; i < array.length; i++) {
if(array[i] == 'o'){
stack.push(i);
}
}
for (int i = 0; i < stack.size(); i++) {
System.out.println(stack.get(i));
}