java.util.scanner

Possible Duplicate: Number of lines in a file in Java I need to count the number of lines of a txt file that is passed to java through a command line argument. I know how to read from a file but i am having trouble doing the rest. any help would be appreciated. here is what i have so far: import java.util.*; import java.io.*; public class LineCounter { public static void main (String [] args) throws IOException{ Scanner file = new Scanner(new File("myFlile.txt")); int count = 0; while(file.hasNext()){ boolean s = file.hasNext(); int count = file.nextInt(); } System.out.println(count); } } Why

I'm having some trouble with getting input from the command line before opening a GUI window. I asked this question previously on Apple Exchange but was sent here after we determined it to be a Programming problem. Basically I'm running a Scanner to get user input before I open up a window but it starts the program, switching spaces on my Mac, and then I have to switch back to the workspace with the terminal in it to answer the question. Here's a link to the original question. https://apple.stackexchange.com/questions/45058/lion-fullscreen-desktop-switching-quirk/45065#comment51527_45065 Here

I'm trying to use Java's Scanner class to scan in double and int values delimited by commas. The following Scanner input = new Scanner(System.in).useDelimiter("\\D"); can only scan int values separated by , . e.g. input = 1000,2,3 How do I scan in double and int values separated by , e.g. input = 1000.00,3.25,5 or 100.00,2,3.5 ? I tried the following but they don't seem to work: Scanner input = new Scanner(System.in).useDelimiter(","); Scanner input = new Scanner(System.in).useDelimiter("\\,"); Scanner input = new Scanner(System.in).useDelimiter("[,]"); Using these seems to hang the code.

I have a very large text file and I need to gather data from somewhere near the end. Maybe Scanner isn't the best way to do this but it would be very wasteful to start at the top and grab 6000 lines before getting to the part of the file I am interested in. Is there a way to either tell Scanner to jump to say 7/8ths down the document or start from the bottom and scan upwards grabbing line by line? Thanks The underlying input source for a java.util.Scanner is a java.lang.Readable . Beyond the Scanner(File) constructor, a Scanner neither knows nor cares of the fact that it's scanning a file.

I'm a beginner in java. I want to check first if the user input is String or Double or int. If it's String, double or a minus number, the user should be prompted to enter a valid int number　again. Only when the user entered a valid number should then the program jump to try. I've been thinking for hours and I come up with nothing useful.Please help, thank you! import java.util.InputMismatchException; import java.util.Scanner; public class Fizz { public static void main(String[] args) { System.out.println("Please enter a number"); Scanner scan = new Scanner(System.in); try { Integer i = scan

Scanner sc = new Scanner(System.in); Scanner can be used for reading text files, user input streams, and more. I am specifically using it for reading user input as is made clear above. With the Scanner that I made above, because it 'rides' System.in, a call to its hasNext() when there is no next input will cause the relevant thread to block until it has data next and return true when it does. I would like to check, getter style, weather there is data next, not, like hasNext() returns, weather there could be data next. Other questions have resolved this by starting a thread to wait over hasNext

Imagine the following scanario: I have a program which ask for an integer input, followed by a String input. int age=0; String name; Scanner sc = new Scanner(System.in); System.out.print("Enter Age: "); age = sc.nextInt(); System.out.print("Enter Name: "); name= sc.nextLine(); With the aobe codes, I was not given a chance to enter the name. So normally I will declare 2 scanner objects as follows: int age=0; String name; Scanner sc = new Scanner(System.in); Scanner sc2 = new Scanner(System.in); //2nd Scanner object System.out.print("Enter Age: "); age = sc.nextInt(); System.out.print("Enter

This question already has an answer here: How to handle infinite loop caused by invalid input (InputMismatchException) using Scanner 5 answers boolean z = false; do { try { a = sc.nextInt(); z = true; } catch(Exception e) { } } while(!z); Try this. If you try an integer the first time it executes properly. However if you enter the wrong type of text it turns into an infinite loop even if you enter an int next and skips assigning the boolean value to true. Why is this? Your problem is from not handling the end of line token and so the scanner is left hanging. You want to do something like so: