We Keep Coding

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.

Compare arraylists for non identical elements

Hello there I am being confused in comparing two array lists, one of my array list is as:
private ArrayList<String> members = new ArrayList<>();
members.add("member123keyxyzmember123 number");
members.add("member456keyxyzmember456 number");
members.add("member789keyxyzmember789 number");
members.add("member2233keyxyzmember2233 number");
members.add("member1122keyxyzmember1122 number");
The second arraylist is as:
private ArrayList<String> syncMembers = new ArrayList<>();
syncMembers.add("member123keyxyz123statuskeyxyz123photokeyxyzmember123 number");
syncMembers.add("member456keyxyz456statuskeyxyz456photokeyxyzmember456 number");
The problem is that I am comparing both so that they give me the numbers that are in members list and are not in syncMembers list!
That is the out put should be:
member789 number
member2233 number
member1122 number
only!
What I have been trying is:
for (int i = 0; i < members.size(); i++) {
String stringFromMembersList = members.get(i);
String[] memberParts = stringFromMembersList.split("keyxyz");
String memberNumber = memberParts[1];
//Log.e("hgax", "sync:::" + memberNumber);
for (int j = 0; j < syncMembers.size(); j++) {
String stringFromSyncList = syncMembers.get(j);
String[] syncParts = stringFromSyncList.split("keyxyz");
String n = syncParts[3];
if (memberNumber.equals(n)) {
//Log.e("hgax", "hee:::" + n);
break;
} else {
Log.e("hgax", "ssshee:::" + memberNumber);
}
}
}
The output I am getting is:
member456 number
member789 number
member789 number
member2233 number
member2233 number
member2233 number
member1122 number
member1122 number
member1122 number
member1122 number
I am bit confuse what is happeing to me and What i have been doing wrong? Can somebody please tell what blunder I am doing Thanks in advance

Try to think about what you need to check to reach your goal. In order to determine that a member in the list members does not exist in syncMembers you have to check the entirety of the syncMembers list for that member. Since the lists are not identical (as your question states), you cannot use Collection.contains(Object o).
This should achieve your goal:
// We need this initial check as if syncMembers is empty it'll display all members
// And why bother to do this if syncMembers is empty anyway!
if (!syncMembers.isEmpty()) {
for (String member : members) {
String memberNo = member.split("keyxyz")[1];
int i = 0;
boolean found = false;
while (!found && i < syncMembers.size()) {
// Iterate over syncMembers until a match if found
// or we have exhausted the list
found = syncMembers.get(i).split("keyxyz")[3].equals(memberNo);
i++;
}
if (!found) {
// Display only if not found
System.out.println(memberNo);
}
}
}

Edit: updated answer to include the original mixed values in the arrayList
ArrayList<String> membersList = new ArrayList<>();
ArrayList<String> syncMembersList = new ArrayList<>();
for (int i = 0; i < members.size(); i++) {
String s = members.get(i).substring(members.get(i).lastIndexOf("member"));
membersList.add(s);
}
for (int j = 0; j < syncMembers.size(); j++) {
String s = syncMembers.get(j).substring(syncMembers.get(j).lastIndexOf("member"));
syncMembersList.add(s);
}
for (int i = 0; i < membersList.size(); i++) {
if (!syncMembersList.contains(membersList.get(i))) {
System.out.println(membersList.get(i));
}
}
This will print the output you require.

Program Overwriting Array with Null

For a project in school (intro to java), we have to make a program using arrays. I decided to make a login program that stores logins. It works perfectly, except when deleting items. This is my code
public void delete() throws FileNotFoundException{
int p;
c.clear();
c.print("Please enter a website to delete it's login info: ");
String delete_name = c.readLine();
Boolean found = false;
// Search for the search key, and display the matching elements
c.println("Searching for " + delete_name + "...");
for (int i = 0; i < pass.length; i++)
if (pass[i][0].equals(delete_name)) {
c.println("Deleting login for " + pass[i][0]);
String new_array[][] = new String[pass.length - 1][3];
//remove an element
for (int w = 0; i < new_array.length; i++)
for (int j = 0; j <= 2; j++) {
p = w;
if (i >= p) {
new_array[w][j] = pass[w + 1][j];
} else {
new_array[w][j] = pass[w][j];
}
}
found = true;
pass = new_array;
}
if (found == false) {
c.println("No luck! " + delete_name + " wasn't found, please try again.");
delete();
}
fileWriter();
}
When it writes to the file, anything after the part that should have been deleted gets changed to "null".
Sorry if the format is awful, I'm just starting with java :) Any help is greatly appreciated, thanks!

When deleting a row of a 2D array in Java, you can use this shortcut (no for-loops needed)
List<String[]> tempArr = new ArrayList<String[]>(Arrays.asList(pass));
//Remove row at index of "delete_name":
for(int i = 0; i < pass.length; i++){
if(pass[i][0].equals(delete_name)){
tempArr.remove(i);
}
}
String[][] new_array = tempArr.toArray(new String[][]{});
However, this solution only works if you are only deleting one object in the List. I would suggest looking into "iterators" to make this solution better.
EDIT:
Here is an example with an iterator
String[][] pass = new String[][]{{"Name","data1","data2"}};
List<String[]> tempArr = new ArrayList<String[]>(Arrays.asList(pass));
for (Iterator<String[]> iterator = tempArr.iterator(); iterator.hasNext();) {
String id = iterator.next()[0];
if (id.equals(delete_name)){
iterator.remove();
}
}

sub arraylist's size isn't correct

After hard searchig I still haven't found the proper answer for my question and there is it:
I have to write a java program that enters an array of strings and finds in it the largest sequence of equal elements. If several sequences have the same longest length, the program should print the leftmost of them. The input strings are given as a single line, separated by a space.
For example:
if the input is: "hi yes yes yes bye",
the output should be: "yes yes yes".
And there is my source code:
public static void main(String[] args) {
System.out.println("Please enter a sequence of strings separated by spaces:");
Scanner inputStringScanner = new Scanner(System.in);
String[] strings = inputStringScanner.nextLine().split(" ");
System.out.println(String.join(" ", strings));
ArrayList<ArrayList<String>> stringsSequencesCollection = new ArrayList<ArrayList<String>>();
ArrayList<String> stringsSequences = new ArrayList<String>();
stringsSequences.add(strings[0]);
for (int i = 1; i < strings.length; i++) {
if(strings[i].equals(strings[i - 1])) {
stringsSequences.add(strings[i]);
} else {
System.out.println(stringsSequences + " " + stringsSequences.size());
stringsSequencesCollection.add(stringsSequences);
stringsSequences.clear();
stringsSequences.add(strings[i]);
//ystem.out.println("\n" + stringsSequences);
}
if(i == strings.length - 1) {
stringsSequencesCollection.add(stringsSequences);
stringsSequences.clear();
System.out.println(stringsSequences + " " + stringsSequences.size());
}
}
System.out.println(stringsSequencesCollection.size());
System.out.println(stringsSequencesCollection.get(2).size());
System.out.println();
int maximalStringSequence = Integer.MIN_VALUE;
int index = 0;
ArrayList<String> currentStringSequence = new ArrayList<String>();
for (int i = 0; i < stringsSequencesCollection.size(); i++) {
currentStringSequence = stringsSequencesCollection.get(i);
System.out.println(stringsSequencesCollection.get(i).size());
if (stringsSequencesCollection.get(i).size() > maximalStringSequence) {
maximalStringSequence = stringsSequencesCollection.get(i).size();
index = i;
//System.out.println("\n" + index);
}
}
System.out.println(String.join(" ", stringsSequencesCollection.get(index)));
I think it should be work correct but there is a problem - the sub array list's count isn't correct: All the sub arrayList's size is 1 and for this reason the output is not correct. I don't understand what is the reason for this. If anybody can help me to fix the code I will be gratefull!

I think it is fairly straight forward just keep track of a max sequence length as you go through the array building sequences.
String input = "hi yes yes yes bye";
String sa[] = input.split(" ");
int maxseqlen = 1;
String last_sample = sa[0];
String longest_seq = last_sample;
int seqlen = 1;
String seq = last_sample;
for (int i = 1; i < sa.length; i++) {
String sample = sa[i];
if (sample.equals(last_sample)) {
seqlen++;
seq += " " + sample;
if (seqlen > maxseqlen) {
longest_seq = seq;
maxseqlen = seqlen;
}
} else {
seqlen = 1;
seq = sample;
}
last_sample = sample;
}
System.out.println("longest_seq = " + longest_seq);

Lots of issues.
First of all, when dealing with the last string of the list you are not actually printing it before clearing it. Should be:
if(i == strings.length - 1)
//...
System.out.println(stringsSequences + " " + stringsSequences.size());
stringsSequences.clear();
This is the error in the output.
Secondly, and most importantly, when you do stringsSequencesCollection.add you are adding an OBJECT, i.e. a reference to the collection. When after you do stringsSequences.clear(), you empty the collection you just added too (this is because it's not making a copy, but keeping a reference!). You can verify this by printing stringsSequencesCollection after the first loop finishes: it will contain 3 empty lists.
So how do we do this? First of all, we need a more appropriate data structure. We are going to use a Map that, for each string, contains the length of its longest sequence. Since we want to manage ties too, we'll also have another map that for each string stores the leftmost ending position of the longest sequence:
Map<String, Integer> lengths= new HashMap<>();
Map<String, Integer> indexes= new HashMap<>();
String[] split = input.split(" ");
lengths.put(split[0], 1);
indexes.put(split[0], 0);
int currentLength = 1;
int maxLength = 1;
for (int i = 1; i<split.length; i++) {
String s = split[i];
if (s.equals(split[i-1])) {
currentLength++;
}
else {
currentLength = 1;
}
int oldLength = lengths.getOrDefault(s, 0);
if (currentLength > oldLength) {
lengths.put(s, currentLength);
indexes.put(s, i);
}
maxLength = Math.max(maxLength, currentLength);
}
//At this point, youll have in lengths a map from string -> maxSeqLengt, and in indexes a map from string -> indexes for the leftmost ending index of the longest sequence. Now we need to reason on those!
Now we can just scan for the strings with the longest sequences:
//Find all strings with equal maximal length sequences
Set<String> longestStrings = new HashSet<>();
for (Map.Entry<String, Integer> e: lengths.entrySet()) {
if (e.value == maxLength) {
longestStrings.add(e.key);
}
}
//Of those, search the one with minimal index
int minIndex = input.length();
String bestString = null;
for (String s: longestStrings) {
int index = indexes.get(s);
if (index < minIndex) {
bestString = s;
}
}
System.out.println(bestString);

Below code results in output as you expected:
public static void main(String[] args) {
System.out.println("Please enter a sequence of strings separated by spaces:");
Scanner inputStringScanner = new Scanner(System.in);
String[] strings = inputStringScanner.nextLine().split(" ");
System.out.println(String.join(" ", strings));
List <ArrayList<String>> stringsSequencesCollection = new ArrayList<ArrayList<String>>();
List <String> stringsSequences = new ArrayList<String>();
//stringsSequences.add(strings[0]);
boolean flag = false;
for (int i = 1; i < strings.length; i++) {
if(strings[i].equals(strings[i - 1])) {
if(flag == false){
stringsSequences.add(strings[i]);
flag= true;
}
stringsSequences.add(strings[i]);
}
}
int maximalStringSequence = Integer.MIN_VALUE;
int index = 0;
List <String> currentStringSequence = new ArrayList<String>();
for (int i = 0; i < stringsSequencesCollection.size(); i++) {
currentStringSequence = stringsSequencesCollection.get(i);
System.out.println(stringsSequencesCollection.get(i).size());
if (stringsSequencesCollection.get(i).size() > maximalStringSequence) {
maximalStringSequence = stringsSequencesCollection.get(i).size();
index = i;
//System.out.println("\n" + index);
}
}
System.out.println(stringsSequences.toString());

How do you copy the components of an ArrayList to a regular Array?

public boolean makeReservation(int id, AvilaNatalyPassenger request) {
boolean status = true;
ArrayList<Integer> inputValues = new ArrayList<Integer>();
for (int i = 0; i < 22; i++) {
for (int j = 0; j < 5; j++) {
id = seats[i][j];
if (id != -1) {
if (inputValues.contains(id)) {
status = false;
break;
}
else {
inputValues.add(id);
for(int a = 0; a < inputValues.size; a++)
seats[a] = inputValues[a];
}
}
}
}
return status;
}
This is what I have but its not correct. I need to add what I have in inputVaule arrayList into the array seats.

You can also look at the Java API: http://docs.oracle.com/javase/7/docs/api/index.html?java/util/ArrayList.html
public Object[] toArray()
Returns an array containing all of the elements in this list in proper sequence (from first to last element).
So this is what you could do:
seats[a] = inputValues.toArray();
Furthermore you cannot use inputValues[a] since it is not an array. What you probably could do is
seats[a] = (inputValues.toArray())[a];

To answer your question, here is an example:
ArrayList<String> stock_list = new ArrayList<String>();
stock_list.add("stock1");
stock_list.add("stock2");
String[] stockArr = new String[stock_list.size()];
stockArr = stock_list.toArray(stockArr);
for(String s : stockArr)
System.out.println(s);
Example is taken from here