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Formatting entered stream data in java

I am curious how to get input data formatted from a user in java, for example if the user enters 1,2,3 how can I get these numbers in an array when the input look like this:
Scanner s = new Scanner();
String inputString = s.nextLine();
I can get a single number
Integer num = Integer.parseInt(inputString)
but I am unsure how handling multiple numbers would go

Well, you'd use... scanner. That's what it is for. However, out of the box a scanner assumes all inputs are separated by spaces. In your case, input is separated by a comma followed by/preceded by zero or more spaces.
You need to tell scanner this:
Scanner s = new Scanner(System.in);
s.useDelimiter("\\s*,\\s*");
s.nextInt(); // 1
s.nextInt(); // 2
s.nextInt(); // 3
The "\\s*,\\s*" think is a regexp; a bit of a weird concept. That's regexpese for 'any amount of spaces (even none), then a comma, then any amount of spaces'.
You could just use ", " too, that'll work, as long as your input looks precisely like that.
More generally if you have a fairly simple string you can use someString.split("\\s*,\\s*") - regexes are used here too. This returns a string array with everything between the commas:
String[] elems = "1, 2, 3".split("\\s*,\\s*");
for (String elem : elems) {
System.out.println(Integer.parseInt(elem));
}
> 1
> 2
> 3

Why am I not getting the correct output in ques of printing even and odd index character seperatly?

enter link description here
This is the link to the question. I have written this code in java but I am not getting the correct output.Why?
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
for(int i=0; i<n; i++)
{
String name = sc.nextLine();
String even="";
String odd ="";
for(int j=0; j<name.length(); j++)
{
if(j%2==0)
even=even+String.valueOf(name.charAt(j));
else
odd=odd+String.valueOf(name.charAt(j));
}
System.out.println(even+" "+odd);
This is the error I am getting.
Input (stdin)
2
Hacker
Rank
Your Output (stdout)
// a blank space here.
Hce akr
Expected Output
Hce akr
Rn ak

Your int n = sc.nextInt(); consumes the integer that's input (2), but there is a still a newline.
When your loop goes through the first time, and you call String name = sc.nextLine();, it will consume that remaining newline (and nothing else). Hence, your blank line.
To get past that, make sure to read in the new line after you read in n
Also, the last entry isn't shown because you likely need a trailing newline (one after "Rank" in your input)

your code is correct but the problem is in your input taking.
if u take this as a input
2
Hacker
Rank
then your excepted output never come as u mentioned in your question.
Now i tell u in brief about where is the problem:---------
int n = sc.nextInt();
here u take integer input 2 but you delare only one string type variable.u must declare 2string typr variable if u choose 2.
otherwise only 1 tring willl be handled .
Hacker
Rank
thatswhy u take 2 string variable bt according to ur code only hacker will be compiled and give the output.
u declare 2 string variable .

Java input/output confusion

I am writing a program and I need to input a value for index, but the index should be composite, e.g 44GH.
My question is, how to make the program to do not crash when I ask the user to input it and then I want to display it?
I have been looking for answer in the site, but they are only for integer or string type.
If anyone can help, would be really appreciated.
Scanner s input = new Scanner(System.in);
private ArrayList<Product> productList;
System.out.println("Enter the product");
String product = s.nextLine();
System.out.println("Input code for your product e.g F7PP");
String code = s.nextLine();
}
public void deleteProduct(){
System.out.println("Enter the code of your product that you want to delete ");
String removed = input.nextLine();
if (productList.isEmpty()) {
System.out.println("There are no products for removing");
} else {
String aString = input.next();
productList.remove(aString);
}
}

Remove all non digits char before casting to integer:
String numbersOnly= aString.replaceAll("[^0-9]", "");
Integer result = Integer.parseInt(numbersOnly);

The best way to do it is to create some RegEx that could solve this problem, and you test if your input matches your RegExp. Here's a good website to test RegExp : Debuggex
Then, when you know how to extract the Integer part, you parse it.

I think the OP wants to print out a string just but correct me if I am wrong. So,
Scanner input = new Scanner(System.in);
String aString = input.nextLine(); // FFR55 or something is expected
System.out.println(aString);
Then obviously you can use:
aString.replaceAll();
Integer.parseInt();
To modify the output but from what I gather, the output is expected to be something like FFR55.

Try making the code split the two parts:
int numbers = Integer.parseInt(string.replaceAll("[^0-9]", ""));
String chars = string.replaceAll("[0-9]", "").toUpperCase();
int char0Index = ((int) chars.charAt(0)) - 65;
int char1Index = ((int) chars.charAt(1)) - 65;
This code makes a variable numbers, holding the index of the number part of the input string, as well as char0Index and char1Index, holding the value of the two characters from 0-25.
You can add the two characters, or use the characters for rows and numbers for columns, or whatever you need.

convert String to arraylist of integers using wrapper class

Im trying to write a program that takes a string of user inputs such as (5,6,7,8) and converts it to an arrayList of integers e.g. {5,6,7,8}. I'm having trouble figuring out my for loop. Any help would be awesome.
String userString = "";
ArrayList<Integer> userInts = new ArrayList<Integer>();
System.out.println("Enter integers seperated by commas.");
userString = in.nextLine();
for (int i = 0; i < userString.length(); i++) {
userInts.add(new Integer(in.nextInt()));
}

If your list consists of single-digit numbers, your approach could work, except you need to figure out how many digits there are in the string before allocating the result array.
If you are looking to process numbers with multiple digits, use String.split on the comma first. This would tell you how many numbers you need to allocate. After than go through the array of strings, and parse each number using Integer.parseInt method.
Note: I am intentionally not showing any code so that you wouldn't miss any fun coding this independently. It looks like you've got enough knowledge to complete this assignment by reading through the documentation.

Lets look at the lines:
String userString = ""
int[] userInt = new int[userString.length()];
At this point in time userString.length() = 0 since it doesnt contain anything so this is the same as writing int[] userInt = new int[0] your instantiating an array that cant hold anything.
Also this is an array not an arrayList. An arrayList would look like
ArrayList<Integer> myList = new ArrayList()<Integer>;

I'm assuming the in is for a Scanner.
I don't see a condition to stop. I'll assume you want to keep doing this as long as you are happy.
List<Integer> arr = new ArrayList<Integer>();
while(in.hasNext())
arr.add(in.nextInt());
And, say you know that you will get 10 numbers..
int count = 10;
while(count-- > 0)
arr.add(in.nextInt());

Might I suggest a different input format? The first line of input will consist of an integer N. The next line contains N space separated integers.
5
3 20 602 3 1
The code for accepting this input in trivial, and you can use java.util.Scanner#nextInt() method to ensure you only read valid integer values.
This approach has the added benefit of validate the input as it is entered, rather than accepting a String and having to validate and parse it. The String approach presents so many edge cases which need to be handled.

Parse a string and cast certain elements to int

I was working on a bit of code where you would take an input of 2 numbers, separated by a comma, and then would proceed to do other actions with the numbers.
I was wondering how I would parse the string to take the first number up to the comma, cast it to and int and then proceed to cast the second number to an int.
Here is the code I was working on:
Scanner Scan = new Scanner(System.in);
System.out.print("Enter 2 numbers (num1,num2): ");
//get input
String input = Scan.nextLine();
//parse string up to comma, then cast to an integer
int firstNum = Integer.parseInt(input.substring(0, input.indexOf(',')));
int secondNum = Integer.parseInt(Scan.nextLine());
Scan.close();
System.out.println(firstNum + "\n" + secondNum);
The first number is cast to an integer just fine, I run into issues with the second one.
Exception in thread "main" java.lang.NumberFormatException: For input string: ""
How would I be able to then take the second integer out of the input string and cast it to an Int.

The error mode you're encountering seems reasonable indeed, as you're reading the next line from the scanner and therefore explicitly no longer operating on the first input anymore.
What you're looking for is probably this:
int secondNum = Integer.parseInt(input.substring(input.indexOf(',') + 1));

When defining secondNum, you're setting it equal to the parsed integer of the next line the scanner object reads, but all of the data has already been read. So rather than read from the scanner again, you'll want to call Integer.parseInt on everything after the comma.

It fails because all digit are given by the user on the same line. and you have two Scanner.nextLine(); the second is probably empty.
here is a solution :
Scanner Scan = new Scanner(System.in);
System.out.print("Enter 2 numbers (num1,num2): ");
//get input
String input = Scan.nextLine();
StringTokenizer st = new StringTokenizer(input, ",");
List<Integer> numbers = new ArrayList<>();
while (st.hasMoreElements()) {
numbers.add(Integer.parseInt(st.nextElement()));
}
System.out.println(numbers);

If input on one line, both the numbers will be stored in the String variable input. You don't need to scan another line. It will be empty, and you cannot cast the empty string to an int. Why not just parse the second number out of input, as you did the first.