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How to search a CSV file based on an input field?

I am able to access only few number of lines (41 lines to be proper).after that I am unable to read.
import java.io.File;
import java.util.Scanner;
public class FileReader {
public static void main(String[] args) {
String filePath = "qwe.csv";
System.out.println("Enter the City name to be Searched\n");
Scanner in = new Scanner(System.in);
String searchTerm = in.nextLine();
readRecord(filePath, searchTerm);
}
public static void readRecord( String filePath, String searchTerm ) {
boolean found = false;
String City = ""; String City_Asciis = ""; String Lattitude = "";
String longitude = ""; String Country = "";
String iso_2 = ""; String iso_3 = ""; String Admin_Name = "";
String Capital = ""; String Population = ""; String Id = "";
try {
File file = new File(filePath);
Scanner x = new Scanner (file);
x.useDelimiter("[,\n]"); //to separate the data items
//hasNext - Returns true if the scanner has another token/value in its input
while(x.hasNext() && !found) {
City = x.next();
City_Asciis = x.next();
Lattitude = x.next();
longitude = x.next();
Country = x.next();
iso_2 = x.next();
iso_3 = x.next();
Admin_Name = x.next();
Capital = x.next();
Population = x.next();
Id = x.next();
if (City.equals(searchTerm)) {
found = true;
}
}
if (found) {
System.out.println(" The following details are of city : " + City +"\n The Ascii string would be : "
+ City_Asciis +"\n Its having the lattitude around : "
+ Lattitude + "\n and Longitude of : "+ longitude +"\n It is situated in : "
+ Country +"\n These have iso code like : "+ iso_2 +" and : "+ iso_3 +"\n It comes under : "
+ Admin_Name +" State \n Capital of this city is : "+ Capital +"\n The population is around : "
+ Population +"\n ZIP code is : "+Id+"");
}
else {
System.out.print("Enter the Correct City Name");
}
}
catch(Exception e1){
System.out.print("file not found \n");
e1.printStackTrace();
}
}
}
This code will load the searched city from the file path given, so that given a particular city name print the details of the city.

Who knows?
Without getting a headache, the code itself looks as though it should work and I personally can't off hand see why your read will only do 41 lines without doing a series of experiments with actual data and not many people really want to do that which is why you've been asked to provide some sample fictitious data.
It could be as simple as the fact that you are satisfying the boolean found variable criteria within the while loop condition and the loop breaks out stopping the read. I would suspect this since you do indicate that the "code will load the searched city from the file path given". I should think that this is not really what you would want for the mere reason that some countries contain the same City names. As a matter of fact, some States, Provinces, or Regions within the same Country can contain same City names. As an example did you know that in the United States alone, there are 88 Cities and Towns named Washington? I know, weird right, especially when you consider that there are only 50 States and 2 Territories. Benjamin Franklin was also one of the Founding Fathers of the United States and there are 35 cities and towns/villages that honorably carry the name of Franklin within that country.
If your data file or database is big enough then I'm sure you would want to display all cities that match your specific search criteria. With that being said perhaps what you need to do is get rid of that && !found condition for the while loop. I personally wouldn't use the Scanner#hasNext() method in the while loop condition either. It's an invitation for disaster since it's more focused towards checking the availability of tokens when used in combination with Scanner#next() rather than actual file lines. Use the Scanner#hasNextLine() in combination with the Scanner#nextLine() method then use the String#split() method to parse the CSV comma (,) delimited data lines one line at a time.
Below I provide a runnable Java code example which demonstrates the above mentioned methods. Your readRecord() method is used but considerably modified to accommodate the following options:
Return a List Interface (List<String>) of City information found
pertaining to the supplied search criteria.
Ignore (skip past) blank or comment lines within the CSV file. Comment lines can start with # or ;.
The option to ignore letter case during the search.
Allow for selection of the desired City Information field to which
the Search Criteria will be applied to. The City Information Fields
are:
City, CityAscii, Latitude, Longitude, Country, ISO2,
ISO3, AdminName, Capital, Population, and ID
Wildcard (? and *) characters can be used when supplying the desired search field so that the entire field name does not need to be provided, for example: lat* for Latitude. So, you can do a City Information search simply based on population if you like instead of a City Name.
Allow for wildcard (? and *) characters to be used within the
supplied search criteria for example: wash*. This tells the method
to search for any city which name starts with Wash like
Washington or Washougal or Washtucna.
Allow for the number of found city instances to be returned.
Below is the runnable code which demonstrates the above mentioned concepts. The code is well commented. There are Regular Expressions used within the code and if you want an explanation of those expressions then copy/paste them into regex101.com.
import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class CityInfoRecords {
public static void main(String[] args) {
/* The appplication is started this way so that there
is no need for static methods or variables.
*/
new CityInfoRecords().startApp(args);
}
// Application Start method.
private void startApp(String[] args) {
String ls = System.lineSeparator(); // Not all OS Consoles work well with "\n"
String filePath = "qwe.csv"; // Path and file name of the data file.
Scanner in = new Scanner(System.in);
// Provide the City Info Field to base search from...
System.out.println("Enter the Data Field you want to search by:" + ls
+ "[City, CityAscii, Lattitude, Longitude, Country" + ls
+ "ISO2, ISO3, AdminName, Capital, Population, ID]" + ls
+ "Wildcards (? and *) can be used:");
String searchField = in.nextLine();
// Provide the Search Criteria to find within the supplied City Info Field.
System.out.println(ls + "Enter the search criteria you are looking for" + ls
+ "in " + searchField + ". Wildcards (? and *) are permitted:");
String searchCriteria = in.nextLine();
// Declare a List Interface of String and fill it
// with the call to the readRecord method.
List<String> cityInfoList = readRecord(filePath, searchField, searchCriteria, 0, "N/A");
// Display the returned List to console window.
for (int i = 0; i < cityInfoList.size(); i++) {
System.out.println(cityInfoList.get(i));
}
}
/**
* Returns a List Interface of the City Information found based on the supplied
* search criteria.<br><br>
*
* #param filePath (String) The full path and file name of the data file to read
* containing City information.<br>
*
* #param searchField (String) The City Information Field to based the supplied
* Search Criteria from. Any City Information Field can be supplied here and
* letter case is optional. The wildcard characters (? and *) can also be used
* here so that the entire field name does not need to be supplied, for example:
* <pre>
* lat* for the Latitude field or
* *asc* for the CityAscii field or
* iso? for either the ISO2 or ISO3 fields or simply
* City for the City field.</pre><br>
*
* The <b>?</b> wildcard character specifies any single alphanumeric character,
* as in ?an, which locates "ran," "pan", "can", and "ban".<br><br>
*
* The <b>*</b> wildcard character specifies zero or more of any alphanumeric
* character, as in corp*, which locates "corp", "corporate", "corporation",
* "corporal", and "corpulent".<br>
*
* #param searchCriteria (String) The search criteria string. This can be any
* string you would like to search for within the supplied City Information
* Field. By default letter case is ignored during searches therefore the
* supplied search criteria string does not need to be letter case specific
* however if you want the search to be case specific then set this methods
* optional ignoreLetterCase parameter to false.<br><br>
*
* Wildcard characters (? and *) can also be used within the Search Criteria
* string so as to expand the search to other possibilities, for example if
* the "City" field is supplied and a criteria string like: "wash*" is supplied
* then any city which name starts with "Wash" will have their city information
* returned.<br><br>
*
* The <b>?</b> wildcard character specifies any single alphanumeric character,
* as in ?an, which locates "ran," "pan", "can", and "ban".<br><br>
*
* The <b>*</b> wildcard character specifies zero or more of any alphanumeric
* character, as in corp*, which locates "corp", "corporate", "corporation",
* "corporal", and "corpulent".<br>
*
* #param numberOfFoundToReturn (int) The number of cities who's information
* should be returned. If 0 is supplied then all cities found will be returned.<br>
*
* #param noDataReplacement (String) Sometimes there is no data supplied for a
* specific field within the data file or the file data line may not contain
* the same amount of delimited data. Rather than returning NULL or Null String
* ("") for empty data fields you can supply here what to actually return in
* such a case. "N/A" is a good choice or perhaps: "Nothing Supplied". Whatever
* you like to use can be supplied here.<br>
*
* #param ignoreLetterCase (Optional - Boolean - Default is true) By default
* searches ignore letter case but if you want your search to be letter case
* specific then you can supply boolean false to this optional parameter.<br>
*
* #return (String List Collection) Information for every City found within the
* supplied data file which matches the supplied field and search criteria.
*/
public List<String> readRecord(String filePath, String searchField,
String searchCriteria, int numberOfFoundToReturn,
String noDataReplacement, boolean... ignoreLetterCase) {
String ls = System.lineSeparator(); // Not all OS Consoles work well with "\n" (property)
boolean ignoreCase = true; // Ignore letter case when searching (Default - property)
if (ignoreLetterCase.length > 0) {
ignoreCase = ignoreLetterCase[0];
}
boolean found = false; // Flag to indicate data was found (toggles)
int foundCounter = 0; // Indicates number of same data found (increments)
List<String> returnableList = // The List of found city information that will be returned (collection)
new ArrayList<>();
// City Information Variables (data fields)
String city;
String cityAscii;
String latitude;
String longitude;
String country;
String iso2;
String iso3;
String adminName;
String capital;
String population;
String id;
// Open Scanner to read data file...
// Try With Resources is used here to auto close the reader.
try (Scanner fileReader = new Scanner(new File(filePath))) {
// Iterate through data file...
while (fileReader.hasNextLine()) {
// Read file line by line and remove leading or
// trailing whitespaces, tabs, line breaks, etc.
String cityData = fileReader.nextLine().trim();
// Skip blank or comment lines (comment lines can be lines that start with # or ;)
if (cityData.equals("") || cityData.startsWith("#") || cityData.startsWith(";")) {
continue; // Get next file line
}
// Split the read line based on any comma delimited anomaly.
String[] cityInfo = cityData.split(",|,\\s+|\\s+,|\\s+,\\s+");
// The number of data pieces split from data line.
// Not all lines may contain the same amount of data.
int i = cityInfo.length;
/* Ternary is used to fill city information variables
so that data not provided will not be null or null string.
As an Example for the city variabel this is the same as:
if (i >= 1 && !cityInfo[0].equals("")) {
city = cityInfo[0].trim();
}
else {
city = noDataReplacement;
}
*/
city = (i >= 1 && !cityInfo[0].equals("")) ? cityInfo[0].trim() : noDataReplacement;
cityAscii = (i >= 2 && !cityInfo[1].equals("")) ? cityInfo[1].trim() : noDataReplacement;
latitude = (i >= 3 && !cityInfo[2].equals("")) ? cityInfo[2].trim() : noDataReplacement;
longitude = (i >= 4 && !cityInfo[3].equals("")) ? cityInfo[3].trim() : noDataReplacement;
country = (i >= 5 && !cityInfo[4].equals("")) ? cityInfo[4].trim() : noDataReplacement;
iso2 = (i >= 6 && !cityInfo[5].equals("")) ? cityInfo[5].trim() : noDataReplacement;
iso3 = (i >= 7 && !cityInfo[6].equals("")) ? cityInfo[6].trim() : noDataReplacement;
adminName = (i >= 8 && !cityInfo[7].equals("")) ? cityInfo[7].trim() : noDataReplacement;
capital = (i >= 9 && !cityInfo[8].equals("")) ? cityInfo[8].trim() : noDataReplacement;
population = (i >= 10 && !cityInfo[9].equals("")) ? cityInfo[9].trim() : noDataReplacement;
id = (i >= 11 && !cityInfo[10].equals("")) ? cityInfo[10].trim() : noDataReplacement;
// Determine the city data field we want to search in
String regex;
// Were wildcards used in the supplied Search Field string?
if (searchField.contains("?") || searchField.contains("*")) {
// Yes... Prep regex to get proper search field
regex = searchField.replace("?", ".?").replace("*", ".*?").toLowerCase();
}
else {
regex = "(?i)(" + searchField + ")";
}
// Get proper search field data
String field = "";
if ("city".toLowerCase().matches(regex)) {
field = city;
}
else if ("cityAsciis".toLowerCase().matches(regex)) {
field = cityAscii;
}
else if ("lattitude".toLowerCase().matches(regex)) {
field = latitude;
}
else if ("longitude".toLowerCase().matches(regex)) {
field = longitude;
}
else if ("country".toLowerCase().matches(regex)) {
field = country;
}
else if ("iso2".toLowerCase().matches(regex)) {
field = iso2;
}
else if ("iso3".toLowerCase().matches(regex)) {
field = iso3;
}
else if ("adminName".toLowerCase().matches(regex)) {
field = adminName;
}
else if ("capital".toLowerCase().matches(regex)) {
field = capital;
}
else if ("population".toLowerCase().matches(regex)) {
field = population;
}
else if ("id".toLowerCase().matches(regex)) {
field = id;
}
if (field.equals("")) {
System.err.println("Invalid Search Field Name Provided! (" + searchField + ")");
return returnableList;
}
// See if the search criteria contains wildcard characters
// A search can be carried out using wildcards in this method.
if (searchCriteria.contains("?") || searchCriteria.contains("*")) {
// There is...build the required Regular Expression (RegEx) to use.
regex = searchCriteria.replace("?", ".?").replace("*", ".*?");
// See if the data item matches the search criteria ignoring letter case if desired.
// The String.matches() method is used for this and ternary for ignoring letter case.
if (ignoreCase ? field.toLowerCase().matches(regex.toLowerCase()) : field.matches(regex)) {
found = true; // toogle flag to true if there is a match.
}
}
// No wildcard characters in search criteria...
// Ternary is used in condition to handle ignore letter case if desired.
else if (ignoreCase ? field.equalsIgnoreCase(searchCriteria) : field.equals(searchCriteria)) {
found = true; // toogle flag to true if there is a match.
}
// If the 'found' flag has been set to true...
if (found) {
// Add City information to returnable ArrayList
String info = ls + "The following details are of city: " + city + ls
+ "The Ascii string would be: " + cityAscii + ls
+ "It has the approximate Lattitude of: " + latitude + ls
+ "And the approximate Longitude of: " + longitude + ls
+ "It is situated in the country of: " + country + ls
+ "The city has iso codes like: " + iso2 + " and: " + iso3 + ls
+ "The State/Province/Region is: " + adminName + ls
+ "Capital of this city is: " + capital + ls
+ // Didn't know cities had capitals
"The population is approximately: " + population + ls
+ "City general ZIP code is: " + id;
returnableList.add(info); // Add to list
found = false; // Toggle found flag back to false in prep to locate more city data.
foundCounter++; // increment the found counter.
// If the First Instance Only flag is true then...
if (numberOfFoundToReturn > 0 && foundCounter == numberOfFoundToReturn) {
// Break out of the 'while' loop. We don't need anymore cities.
break;
}
}
}
// If the Found Counter was not incremented then
// we didn't find any data in file... Inform User.
if (foundCounter == 0) {
System.err.print(ls + "Can not find City Name (" + searchCriteria
+ ") in data file!" + ls);
}
}
catch (FileNotFoundException ex) {
System.err.print("City Data file not found! (" + filePath + ")" + ls);
}
// Return the List of found data.
return returnableList;
}
}
Create a new Java Application Project and name it CityInfoRecords. Copy and paste the above code over top of the Main Startup class. Run the application, read the console prompts carefully and enter the proper data.
The first prompt asks for a City Information Field name...enter: city.
The second prompt will ask for the search criteria for city...enter a city name in Upper or lower case (it doesn't matter). The city information will be displayed in console but only if that city name is contained within the City field within the data file.
Now run the code again and enter the same data except this time, for the city name just provide the first three letters of a city name and an asterisk (*) and then hit the enter key. Now any city information within your specific City Data File which starts with those supplied three letters will be displayed within the Console Window.
Play with it, try different fields to search from and play with the wildcard characters as well with your supplied field or search criteria data.
Now make readRecord a Class instead of a method which would be better.

ChangePassword method in Java

I'm working on a Java project, building a simple system, and it has some methods, one of them is "Change PassWord", I put the user's information (username & password) in a text file called ("Users.txt").
Now this is the description of the method:
boolean ChangePassWord(): Asks the user to enter old password for
verification, the user has at maximum three tries to enter correct old
password; if not the password will not be changed and a message Box
will be shown for the user. If user entered correct old password then
he is authenticated to changer his password and asked to enter new
password and confirming the new. Once if confirmed correctly the old
password will be changed to the new one and a message box will be
shown if wrong confirmation the old password will not be changed and a
message box will be shown.
I wrote this code:
boolean changePassword(){
String pass=JOptionPane.showInputDialog(null, "Enter old password: ", "Input", JOptionPane.QUESTION_MESSAGE);
if(pass.equals(Password)) {
String newpass=JOptionPane.showInputDialog(null,
"Enter new password: ", "Input", JOptionPane.QUESTION_MESSAGE);
String connewpass=JOptionPane.showInputDialog(null,
"Enter confirming new password: ", "Input",
JOptionPane.QUESTION_MESSAGE);
if(newpass.equals(connewpass)){
Password= newpass;
JOptionPane.showMessageDialog(null, "password changed ", "message",
JOptionPane.INFORMATION_MESSAGE);
return true;
}
else
JOptionPane.showMessageDialog(null, "Wrong Conferm ", "message",
JOptionPane.INFORMATION_MESSAGE);
}
else
JOptionPane.showMessageDialog(null, "Wrong password ", "message",
JOptionPane.INFORMATION_MESSAGE);
return false;
}
but I think that it's wrong, and I need to use a loop I think.
I hope you help me!

A while loop is appropriate for your case. I will briefly explain how this while loop runs 3 times.
So, first n=3. The condition n-- > 0 means 2 things. Check if n is greater than zero and subtract the value of n by 1. These 2 things happen in that exact order.
So the condition checks that n is indeed greater than zero and enters the loop. At the same time n is also decreased by 1 and becomes 3-1=2.
This goes on 3 times. After the 3rd time, n becomes 0. And the condition 0 > 0 is false and therefore the while loop breaks.
boolean changePassword(){
String pass = ""; //get old password from user
int n = 3;
while (n-- > 0) {
if(pass.equals(Password)) {
String newPass = ""; // get new password from user
String conNewPass = ""; // confirm new password from user
if (newPass.equals(conNewPass)) {
Password = newPass;
// password changed
return true;
} else {
// wrong confirmation.. password not changed
return false;
}
}
else {
// tell user to enter the correct old password
pass = ""; // ask user for old password again
}
}
// show error message that user entered the old password 3 times incorrectly
// and return false
return false;
}

Java - Check online password

This is from Liang's Java Book. Basically, I have to check with a method if a certain word could be used as password.
/*
(Check password) Some websites impose certain rules for passwords. Write a
method that checks whether a string is a valid password. Suppose the password
rules are as follows:
■ A password must have at least eight characters.
■ A password consists of only letters and digits.
■ A password must contain at least two digits.
Write a program that prompts the user to enter a password and displays Valid
Password if the rules are followed or Invalid Password otherwise.
*/
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
System.out.println("This program checks if the password prompted is valid, enter a password:");
Scanner input = new Scanner(System.in);
String password = input.nextLine();
if (isValidPassword(password))
System.out.println("The password is valid.");
else
System.out.println("The password is not valid.");
public static boolean isValidPassword (String password) {
if (password.length() >= 8) {
// if (regex to include only alphanumeric characters?
// if "password" contains at least two digits...
return true;
}
Also, what if (not required) would I to display the exact kind of error? For instance, if I would notify the user that only a kind of error has occurred (e.g. "Your password length is OK, but there are no digits in your password")?

I would do this way:
public class Test {
public static String passwordChecker(String s){
String response = "The password";
int countdigits = 0;
Pattern pattern = Pattern.compile("[0-9]");
Matcher matcher = pattern.matcher(s);
while(matcher.find()){
++countdigits;
}
if(s.length() >= 8){
response = response + ": \n-is too short (min. 8)";
}
else if(!(s.toLowerCase().matches("[a-z]+") && s.matches("[0-9]+"))){
response = response + "\n-is not alphanumeric";
}
else if(countdigits < 2){
response = response + "\n-it doesn't contains at least 2 digits";
}
else{
response = response + " ok";
}
return response;
}
public static void main(String[] args) {
System.out.println("This program checks if the password prompted is valid, enter a password:");
Scanner input = new Scanner(System.in);
String password = input.nextLine();
System.out.println(passwordChecker(password));
}
}
Oops, I forgot to add the rules; well, just use System.out.println :)

How can I check if a string is available in a table?

Here's the table (tblemployees)
How can I convert my code that used text files to a code that will use database (tables).
int intcurrentLine = -1;
String[] strLineSplit = (sb.toString()).split("\\r?\\n"); // converts sb to string then splits it by line
int intNumElements = strLineSplit.length; // number of elements
while (intcurrentLine != (intNumElements - 1)) {
intcurrentLine++;
String[] strWords = (strLineSplit[intcurrentLine]).split(" ", 2); // splits the current line by the first instance(space)
if (strEmpID.equals(strWords[0])) { // checks if the employee ID is available
JOptionPane.showMessageDialog(null, "Welcome " + strWords[1] + ", you have successfully logged in.");
strCheck = 1; // to confirm and go to time in and out process
break;
}
if ((intcurrentLine + 1) == intNumElements) { // condition to state that ID cant be found from the employee list
JOptionPane.showMessageDialog(null, "No such employee, please check the ID No. that you entered.");
}
}
Now I would like to search a column if it contains an Employee number. How do I put it to a condition, I've been searching but unable to find a clear answer. They only put how to search like this
String queryCheck = "SELECT * from messages WHERE EmpIDNo = 'COMSCI0001'";
ResultSet res = st.executeQuery(queryCheck);
then I'm lost, how to make a condition where if the employee no. doesn't exists something would happen else something would happen. I'm just confuse how to make a condition for that.

You can do like this:
String queryCheck = "SELECT * FROM messages WHERE EmpIDNo = 'COMSCI0001' LIMIT 1";
ResultSet res = st.executeQuery(queryCheck);
boolean exists = res.next();
The boolean variable exists will indicate whether a matching record exists or not.
Notice that I added LIMIT 1 at the end of the SQL as an optimization to avoid fetching more data than you really need.

Want to get single database value

I have a login form which if is success to login. I want to get a name of the logged, here see my code:
try {
if(jTextField1.getText().equals(""))
{
JOptionPane.showMessageDialog(null, "Pleass Input Username");
}
else if(jPasswordField1.getText().equals(""))
{
JOptionPane.showMessageDialog(null, "Please Input Password");
}
else
{
rs = con.executeQuery("SELECT * FROM MsEmployee WHERE EmployeeID='"+jTextField1.getText()+"' And Password='"+jPasswordField1.getText()+"'");
if (rs.next())
{
help.IDemployee = jTextField1.getText();
JOptionPane.showMessageDialog(null, "Login Success! welcome "+ help.IDemployee);
MainMenu mm = new MainMenu(true);
mm.setVisible(true);
this.dispose();
}else
{
JOptionPane.showMessageDialog(null, "Username not found!!");
}
}
} catch (SQLException ex) {
JOptionPane.showMessageDialog(null,ex.getMessage());
}
So I want to display the EmployeeName from MSEmployee which it got from EmployeeID.
I think something like this:
String qry;
qry = "Select EmployeeName From MsEmplyee WHERE EmployeeID = '" + jtextField1.gettext() + "'" ;
But when I compile, its just print the text above, not get the value. Can anyone help please?

As suggested in a comment, please check which name, MsEmplyee/MsEmployee, is correct.
This is not related to your problem but I think there can be one (possible) improvement in your code.
Instead of using
if(jTextField1.getText().equals(""))
It is better to use trim() method before using equals() method. So if user enters a space in jTextField1, your check will be bypassed in this case. So better to use trim() method to remove all first and last space characters from the string.
if(jTextField1.getText().trim().equals(""))
Same can be done for password field.

You did not read the result set value.
// help.IDemployee = jTextField1.getText();
help.IDemployee = rs.getString(1);
The column index is from 1 for the first column. Not from 0

You Can Try This !
String EmployeeName = rs.getString("Column Label In Database (Like EmployeeName)");
System.out.println(EmployeeName);