Develop Reference

how to input username by getting the half of the first name and half of the last name and the day of the given birthday

example of output should be
please help thank you in advance!!
the output of the code in username should be the 2 letter in firt name and 3 in last name and date number
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner sc = new Scanner(System.in);
System.out.println("Enter Fullname:");
String fullname = sc.nextLine();
System.out.println("Enter Birthday : ");
String bday = sc.nextLine();
System.out.println("Your Login Details");
System.out.println("Enter Fullname:" + fullname);
System.out.println("Enter Birthday : " + bday);
System.out.println("Enter Username: " + );
}
}

Assuming the input will always be in the format you provided, you can use String.split() and String.substring() to extract the required information from the input as shown below.
String[] splitName = fullName.split(" ");
String firstName = splitName[0];
String lastName = splitName[1];
String day = bday.split("-")[1];
String username = firstName.substring(0, 2) + lastName.substring(0, 3) + day;

You can use this code to achieve the expected result. The name should always be in this format FirstName LastName, otherwise, you may encounter NullPointerException more frequently. There are split and substring methods in the string class. Follow these steps to get started
Full name should be split into two strings, the first is for the first name and another is for the last name, for this we will use the split method which returns String[].
After splitting the full name, the substring method comes into the picture, substring method takes two parameters first and the last index. We can use this method with both strings received by the split method.
String[] firstLastName = fullname.split(" ");
System.out.println("Enter Username: " + firstLastName[0].substring(0, 2) + firstLastName[1].substring(0, 3) + bday.split("-")[1]);
Syntax
Public String [] split ( String regex, int limit)
public String substring(int begIndex, int endIndex)

Java - String splitting

I read a txt with data in the following format: Name Address Hobbies
Example(Bob Smith ABC Street Swimming)
and Assigned it into String z
Then I used z.split to separate each field using " " as the delimiter(space) but it separated Bob Smith into two different strings while it should be as one field, same with the address. Is there a method I can use to get it in the particular format I want?
P.S Apologies if I explained it vaguely, English isn't my first language.
String z;
try {
BufferedReader br = new BufferedReader(new FileReader("desc.txt"));
z = br.readLine();
} catch(IOException io) {
io.printStackTrace();
}
String[] temp = z.split(" ");

If the format of name and address parts is fixed to consist of two parts, you could just join them:
String z = ""; // z must be initialized
// use try-with-resources to ensure the reader is closed properly
try (BufferedReader br = new BufferedReader(new FileReader("desc.txt"))) {
z = br.readLine();
} catch(IOException io) {
io.printStackTrace();
}
String[] temp = z.split(" ");
String name = String.join(" ", temp[0], temp[1]);
String address = String.join(" ", temp[2], temp[3]);
String hobby = temp[4];
Another option could be to create a format string as a regular expression and use it to parse the input line using named groups (?<group_name>capturing text):
// use named groups to define parts of the line
Pattern format = Pattern.compile("(?<name>\\w+\\s\\w+)\\s(?<address>\\w+\\s\\w+)\\s(?<hobby>\\w+)");
Matcher match = format.matcher(z);
if (match.matches()) {
String name = match.group("name");
String address = match.group("address");
String hobby = match.group("hobby");
System.out.printf("Input line matched: name=%s address=%s hobby=%s%n", name, address, hobby);
} else {
System.out.println("Input line not matching: " + z);
}

I can think of three solutions.
In order from best to worst:
Different delimiter
Enforce the format to always have two names, two address parts and one hobby
Have a dictionary with names and hobbies, check each word to determine which type it is and then group them together as needed.
(The 3rd option is not meant as a serious alternative.)

As others have mentioned, using spaces as both field delimiter and inside fields is problematic. You could use a regex pattern to split the line (paste (\w+ \w+) (\w+ \w+) (.+) in Regex101 for an explanation):
Pattern pattern = Pattern.compile("(\\w+ \\w+) (\\w+ \\w+) (.+)");
Matcher matcher = pattern.matcher("Bob Smith ABC Street Bowling Fishing Rollerblading");
System.out.println("matcher.matches() = " + matcher.matches());
for (int i = 0; i <= matcher.groupCount(); i++) {
System.out.println("matcher.group(" + i + ") = " + matcher.group(i));
}
This would give the following output:
matcher.matches() = true
matcher.group(0) = Bob Smith ABC Street Bowling Fishing Rollerblading
matcher.group(1) = Bob Smith
matcher.group(2) = ABC Street
matcher.group(3) = Bowling Fishing Rollerblading
However this only works for this exact format. If you get a line with three name parts for example:
John B Smith ABC Street Swimming
This will get split into John B as the name, Smith ABC as the address and Street Swimming as hobbies.
So either make 100% sure your input will always match this format or use a different delimiter.

The split() method majorly works on the 2 things:
Delimiter and
The String Object
Sometimes on limit too.
Whatever limit you will provide, the split() method will do its work according to that.
It doesn't understand whether the left substring is a name or not, same as for the right substring.
Have a look at this code snippet:
String assets = "Gold:Stocks:Fixed Income:Commodity:Interest Rates";
String[] splits = assets.split(":");
System.out.println("splits.size: " + splits.length);
for(String asset: splits){
System.out.println(assets);
}
OutPut
splits.size: 5
Gold
Stocks
Fixed Income // with space
Commodity
Interest Rates // with space
The output came with spaces because I provided the ; as a delimiter.
This probably helped you to get your answer.
Find Detailed Information on Split():
Top 5 Use cases of Split()
Java Docs : Split()

It depends on the data you're dealing with. Will the name always consist of a first and last name? Then you can simply combine the first two elements from the resulting array into a new string.
Otherwise, you might have to find a different way to separate out the different pieces within the txt file. Possibly a comma? Some character that you know won't ever be used in your normal data.

Assuming that every line follows the format
Bob Smith ABC Street Swimming
ie, name surname.... this code can manually manipulate the data for you:
String[] temp = z.split(" ");
String[] temp2 = new String[temp.length - 1];
temp2[0] = temp[0] + " " + temp[1];
for (int i = 2; i < temp.length; i++) {
temp2[i] = temp2[i];
}
temp = temp2;

How to ignore white spaces in Java [duplicate]

This question already has answers here:
Remove all occurrences of char from string
(13 answers)
Closed 5 years ago.
I was wondering how to ignore spaces in Java. This program allows you to enter your first, middle and surname which then outputs your initials. I'm now trying to make it ignore any white spaces. Thanks in advance!
String fullName;
char firstName;
char secondName;
char surname;
int space1;
int space2;
System.out.println("Please enter your first name, your second name and your surname: ");
fullName = kybd.nextLine();
firstName = fullName.charAt(0);
space1 = fullName.indexOf(" ");
secondName = fullName.charAt(space1 + 1);
space2 = fullName.lastIndexOf(" ");
surname = fullName.charAt(space2 + 1);
System.out.println("Initials: " + firstName + secondName + surname);

Explanation
You can implicitly ignore them by just removing them from your input text.
Therefore replace all occurrences with "" (empty text):
fullName = fullName.replaceAll(" ", "");
After that call fullName won't contain a whitespace anymore.
However you'll then get a problem with your logic as you split on whitespaces.
Solution
An alternative could be to first trim the text (removing leading and trailing whitespaces). Then do your split and after that you can remove all other whitespaces:
fullName = kybd.nextLine();
// Remove leading and trailing whitespaces
fullName = fullName.trim();
// Bounds
firstSpace = fullName.indexOf(" ");
lastSpace = fullName.lastIndexOf(" ");
// Extract names
String fullFirstName = fullName.substring(0, firstSpace);
String fullSecondName = fullName.substring(firstSpace + 1, lastSpace);
String fullSurname = fullName.substring(lastSpace + 1);
// Trim everything
fullFirstName = fullFirstName.trim(); // Not needed
fullSecondName = fullSecondName.trim();
fullSurname = fullSurname.trim();
// Get initials
firstName = fullFirstName.charAt(0);
secondName = fullSecondName.charAt(0);
surname = fullSurname.charAt(0);
Example
Let's take a look at an example input (_ stands for whitespace):
__John___Richard_Doe_____
We will first trim fullName and thus get:
John___Richard_Doe
Now we identify the first and the last whitespace and split on them:
First name: John
Second name: ___Richard
Surname: _Doe
Last we also trim everything and get:
First name: John
Second name: Richard
Surname: Doe
With charAt(0) we access the initials:
First name: J
Second name: R
Surname: D
More dynamic
Another more dynamic approach would be to merge all successive whitespaces into a single whitespace. Therefore you would need to traverse the text from left to right and start recording once you see a whitespace, end recording if visiting a non-whitespace character, then replace that section by a single whitespace.
Our example then is:
_John_Richard_Doe_
And after an additional trim you can use your regular approach again:
John_Richard_Doe
Or you can use split(" ") and then reject every empty String:
Iterator<String> elements = Pattern.compile(" ").splitAsStream(fullName)
.filter(e -> !e.isEmpty()) // Reject empty elements
.collect(Collectors.toList()) // Collect to list
.iterator() // Iterator
firstName = elements.next().charAt(0);
secondName = elements.next().charAt(0);
surname = elements.next().charAt(0);
Using the example again the Stream first consists of
"", "", "John", "", "", "Richard", "Doe", "", "", "", "", ""
after the filtering it's
"John", "Richard", "Doe"
Minus Sign
As you said you also want
Richard Jack Smith-Adams
output RJS-A, you can simply split on - after splitting on the whitespace.
Pattern spacePatt = Pattern.compile(" ");
Pattern minusPatt = Pattern.compile("-");
String result = spacePatt.splitAsStream(fullName) // Split on " "
.filter(e -> !e.isEmpty()) // Reject empty elements
.map(minusPatt::splitAsStream) // Split on "-"
.map(stream ->
stream.map(e -> e.substring(0, 1))) // Get initials
.map(stream ->
stream.collect(Collectors.joining("-"))) // Add "-"
.collect(Collectors.joining("")); // Concatenate
Which outputs RJS-A.
This approach is a bit more complicated as we need to maintain the information of the sub-streams, we can't just flatMap everything together, otherwise we wouldn't know where to add the - again. So in the middle part we are indeed operating on Stream<Stream<String>> objects.

I think what you're after here is the split method in String
Which you could use like this:
String fullName = "John Alexander Macdonald";
String[] split = fullName.split(" "); // ["John", "Alexander", "Macdonald"]
The other thing you might want is the trim method which removes spaces from the front and the back of a string.
String withSpaces = " a b c ";
String trimmed = withSpace.trim(); // "a b c"

useDelimeter(",") not working

I have a text file that holds data like this:
Jones,Mary,903452
4342,2.5,A
3311,4,B+
I'm using Scanner to read the file. This is my code:
while(reader.hasNextLine())
{
reader.useDelimiter(",");
String lastN = reader.next();
String firstN = reader.next();
String id = reader.nextLine();
String course1 = reader.next();
double credits = reader.nextDouble();
String grade = reader.nextLine();
}
But when I print the line on the console, the , on the last part of the line doesn't get delimited and it prints like this:
Jones, Mary, ,903452
4342, 2.5, ,A
6.5, ,3.569
My toString method on my class:
public String toString() {
return lastName + ", " + firstName + ", " + idNo + "\n"
+ courseOne + ", " + credits + ", " + grade;
I'm searched around for a solution. I tried reader.useDelimiter("[,]") and reader.useDelimiter(",|,") but still gives me the same output. How can I fix this?

From the Scanner's documentation:
This method returns the rest of the current line, excluding any line separator at the end. The position is set to the beginning of the next line.
(Emphasis mine) This means that the whole rest of the line is returned, including delimiters. Setting id to reader.next() wouldn't work because it sucks up everything until the next delimiter. A better solution would be to make it accept line breaks as a delimiter, like so:
reader.useDelimiter("[,\n]");

How to include white spaces in next() without using nextLine() in Java

I am trying to make the user input a string, which can both contain spaces or not. So in that, I'm using NextLine();
However, i'm trying to search a text file with that string, therefore i'm using next() to store each string it goes through with the scanner, I tried using NextLine() but it would take the whole line, I just need the words before a comma.
so far here's my code
System.out.print("Cool, now give me your Airport Name: ");
String AirportName = kb.nextLine();
AirportName = AirportName + ",";
while (myFile.hasNextLine()) {
ATA = myFile.next();
city = myFile.next();
country = myFile.next();
myFile.nextLine();
// System.out.println(city);
if (city.equalsIgnoreCase(AirportName)) {
result++;
System.out.println("The IATA code for "+AirportName.substring(0, AirportName.length()-1) + " is: " +ATA.substring(0, ATA.length()-1));
break;
}
}
The code works when the user inputs a word with no spaces, but when they input two words, the condition isn't met.
the text file just includes a number of Airports, their IATA, city, and country. Here's a sample:
ADL, Adelaide, Australia
IXE, Mangalore, India
BOM, Mumbai, India
PPP, Proserpine Queensland, Australia

By default, next() searches for first whitespace as a delimiter. You can change this behaviour like this:
Scanner s = new Scanner(input);
s.useDelimiter("\\s*,\\s*");
By this, s.next() will match commas as delimiters for your input (preceeded or followed by zero or more whitespaces)

Check out the String#split method.
Here's an example:
String test = "ADL, Adelaide, Australia\n"
+ "IXE, Mangalore, India\n"
+ "BOM, Mumbai, India\n"
+ "PPP, Proserpine Queensland, Australia\n";
Scanner scan = new Scanner(test);
String strings[] = null;
while(scan.hasNextLine()) {
// ",\\s" matches one comma followed by one white space ", "
strings = scan.nextLine().split(",\\s");
for(String tmp: strings) {
System.out.println(tmp);
}
}
Output:
ADL
Adelaide
Australia
IXE
Mangalore
India
BOM
Mumbai
India
PPP
Proserpine Queensland
Australia