Develop Reference

Output an array to the console from a .txt file

I am trying to copy the contents of a .txt file to an array and print it to the console.
The code requires a main method with two scanners (one to read input from the user, and the second to read the file), a method to make the array, and a method to print the array.
I have successfully managed to make an array and print it, but the output is not ideal. It is scattered and difficult to read. Can someone help me to improve my output so it reads more like a list?
Here is my code:
public class CutupSongCreator {
// Creates two Scanner objects; one reads input from console, the other scans a file
public static void main(String[] args) throws FileNotFoundException {
Scanner console = new Scanner(System.in); // SCANNER ONE (reads input)
System.out.print("What is the input filename? ");
String filename = console.next();
File f = new File(filename);
while (!f.exists()) {
System.out.print("That file does not exist. Try again: ");
filename = console.next();
f = new File(filename);
}
Scanner input = new Scanner(f); // SCANNER TWO (reads file)
SongLine[] arr = makeArray(input);
printArray(arr);
// Sort by genre
// System.out.print("What genre are you looking for: ");
// String genretype = console.next();
// if (genretype == input.next()) {
// System.out.print("You can't just make up a genre. Try again: ");
// genretype = console.next();
// }
// listLinesByGenre(arr, genretype);
}
// Creates an array of SongLines from a set of lines
public static SongLine[] makeArray(Scanner reader) {
int total = reader.nextInt(); // First int = # of lines
SongLine[] arr = new SongLine[total]; // New array to hold the length of the file
for(int i = 0;i < total; i++) {
String genre = reader.next();
int lineNumber = reader.nextInt();
String words = reader.nextLine();
SongLine temp = new SongLine(genre, lineNumber, words);
arr[i] = temp;
}
reader.close();
return arr;
}
// Prints out the elements of an array
public static void printArray(SongLine[] songs) {
System.out.println(Arrays.toString(songs));
}
}
My code makes use of a constructor class, which I could post if needed, but I think I just do not understand how to read or use the constructor file. Below are the current and desired output. The desired shows the genre, lineNumber, and script, and I would like to print it looking as so.
Current Output
Desired Output
Thank you.

java find a specific line in a file based on the first word

I have a file that I am importing and what I want do is ask for the user's input and use that as the basis for finding the right line to examine. I have it set up like this:
public class ReadLines {
public static void main(String[] args) throws FileNotFoundException
{
File fileNames = new File("file.txt");
Scanner scnr = new Scanner(fileNames);
Scanner in = new Scanner(System.in);
int count = 0;
int lineNumber = 1;
System.out.print("Please enter a name to look up: ");
String newName = in.next();
while(scnr.hasNextLine()){
if(scnr.equals(newName))
{
String line = scnr.nextLine();
System.out.print(line);
}
}
}
Right now, I am just trying to get it to print out to see that I have captured it, but that's not working. Does anyone have any ideas? Also, if it matters, I can't use try and catch or arrays.
Thanks a lot!

You need to cache the line in a local variable so you can print it out later. Something like this should do the trick:
while(scnr.hasNextLine()){
String temp = scnr.nextLine(); //Cache variable
if (temp.startsWith(newName)){ //Check if it matches
System.out.println(temp); //Print if match
}
}
Hope this helps!

I'd do something in the lines of:
Scanner in = new Scanner(System.in);
System.out.print("Please enter a name to look up: ");
String name = in.next();
List<String> lines = Files.readAllLineS(new File("file.txt").toPath(), StandardCharsets.UTF_8);
Optional<String> firstResult = lines.stream().filter(s -> s.startsWith(name)).findFirst();
if (firstResult.isPresent) {
System.out.print("Line: " + firstResult.get());
} else {
System.out.print("Nothing found");
}

Line/Token based processing (java)

I'm writing a program to read data from files with various sports statistics. Each line has information about a particular game, in say, basketball. If a particular line contains an "#" symbol, it means that one of the teams is playing at home. I'm trying to count the lines that contain an "#" and output that to the user as the Number of Games in which either team played at home. The first file has that 9 games were played at home for some team, but my output keeps printing out 0 rather than 9. How can I fix this?
Here's the relevant code:
public static void numGamesWithHomeTeam(String fileName) throws IOException{
File statsFile = new File(fileName);
Scanner input1 = new Scanner(statsFile);
String line = input1.nextLine();
Scanner lineScan = new Scanner(line);
int count = 0;
while(input1.hasNextLine()){
if(line.contains("#")){
count++;
input1.nextLine();
} else{
input1.nextLine();
}
}
System.out.println("Number of games with a home team: " + count);
}

Your line variable always has the first line's value. You should set line in the loop, something like that.
while(input1.hasNextLine()){
if(line.contains("#")){
count++;
line = input1.nextLine();
} else{
line = input1.nextLine();
}
Edit: On the second look your code has other problem: the last line is never checked. You should not initialize line (set to null) and do the check after nextLine():
public static void numGamesWithHomeTeam(String fileName) throws IOException{
File statsFile = new File(fileName);
Scanner input1 = new Scanner(statsFile);
String line = null;
Scanner lineScan = new Scanner(line);
int count = 0;
while(input1.hasNextLine()){
line = input1.nextLine();
if(line.contains("#")){
count++;
}
}
System.out.println("Number of games with a home team: " + count);}

How do I get the list of numbers off of a file that the user inputs in Java?

I am using Java eclipse and I would like to have the user input the filename to retrieve a list of scores from the file. My goal is to take the average of those numbers. What line of code do I need just to get the user to input a file name and for the program to take those numbers so that I can compute with them? Currently I can have the user input scores, But I need to get the numbers from the file instead. I have visited numerous resources on this site. Here are a few:
BufferedReader, Error finding file, Getting a list from a file
package Average;
/**An average of scores*/
import java.util.Scanner;
public class Average2 {
public static void main(String[] args) {
int grade = 0;
int students = 0;
float total = 0;
double average = 0;
Scanner input = new Scanner(System.in);
System.out.println("Enter number of students: ");
students = input.nextInt();
if (students <= 10) {
System.out.println("Enter the grades of the students: ");
for(int i = 0; i < students; i++) {
do {
grade = input.nextInt();
} while(grade < 0 || grade > 100);
total += grade;
}
average = (total/students);
int median = ((82+84)/2);
System.out.println("The average is " + average);
System.out.println("The mean is " + median);
}
}
}
Update since above post!
package trials;
import java.io.File;
import java.io.IOException;
import java.util.Scanner;
public class trials2 {
public static void main(String[] args) throws IOException {
// TODO Auto-generated method stub
// Create new Scanner object to read from the keyboard
Scanner in = new Scanner(System.in);
// Grab the name of the file
System.out.println("Enter filename: ");
String fileName = in.next();
// Access the file
Scanner fileToRead = new Scanner(new File(fileName));
// While there is still stuff in the file...
double sum = 0;
while (fileToRead.hasNext()) {
if (fileToRead.hasNextDouble()) {
sum += fileToRead.nextDouble();
} else {
fileToRead.next();
}
}
{
fileToRead.close();
}
System.out.println(sum);
}
}
The results I get from this:
Enter filename:
esp.txt <--entered by me
501.0

Given that you want to find the average of numbers in a file, you could do something like this:
// Create new Scanner object to read from the keyboard
Scanner in = new Scanner(System.in);
// Grab the name of the file
System.out.println("Enter filename: ");
String fileName = in.next();
// Access the file
Scanner fileToRead = new Scanner(new File(fileName));
// Initialize our relevant counters
double sum = 0.0;
int numStudents = 0;
// While there is still stuff in the file...
while (fileToRead.hasNext()) {
// Is this next line consisting of just a number?
if (fileToRead.hasNextDouble()) {
// If it is, accumulate
sum += fileToRead.nextDouble();
numStudents++;
}
else { // Else, just skip to the next line
fileToRead.next();
}
}
// Close the file when finished
fileToRead.close();
// Print the average:
System.out.println("The average mark is: " + (sum / numStudents));
This code will create a new Scanner object that will read input from your keyboard. Once it does that, you type in the file name, and it gets access to this file by opening another Scanner object. After that, we initialize some counters to help us calculate the average. These are sum, which will add up all of the marks we encounter and numStudents, which keeps track of how many students there are in the file.
The while loop will keep looping through each line of this file until it reaches the end. What is important is that you check to see whether or not the line you are reading in next consists of a single number (double). If it is, then add this to our sum. If it isn't, skip to the next line.
Once you're finished, close the file, then display the average by taking the sum and dividing by the total number of students we have encountered when reading the numbers in the file.
Just took a look at your profile and your profile message. You have a long road ahead of you. Good luck!

Look at the Java tutorial on Scanning: http://docs.oracle.com/javase/tutorial/essential/io/scanning.html, particularly the ScanSum example. It shows how to scan double values from a text file and add them. You should be able to modify this example for your project.

Scanner userInput = new Scanner(System.in);
System.out.println("ENter filename");
String fileName = userInput.next();
Scanner fileScan = new Scanner(new File(fileName));
then use scanner methods to process lines or string tokens you are interested in.

What's wrong with this file Scanner code?

I am trying to search the File for characters in Java language. For that I am using Scanner to scan the file.
Well to check the Heirarchy work, I am using System.out.print("Worked till here!"); so that I can check whether it is executed or not. I was able to execute the code till the last stage, but then I found that the essential boolean variable wasn't altered, which was under the condition to check whether there is a character match or not.
The file contents are as
Ok, here is some text!
Actually this file is created to test the validity of the java application
Java is my favourite programming language.
And I think I can score even more :)
Wish me luck!
However, no matter what I search it always prompts me to be false.
Here is the code I am using
public static void main (String[] args) throws IOException {
// Only write the output here!!!
System.out.print("Write the character to be found in the File: ");
Scanner sc = new Scanner(System.in);
String character = sc.next();
// Find the character
System.out.println("Searching now...");
getCharacterLocation(character);
// Close the resource!
sc.close();
}
The method call executed and the method is as
public static void getCharacterLocation (String character) throws IOException {
System.out.println("File found...");
File file = new File("res/File.txt");
Scanner sc = new Scanner(file);
int lineNumber = 0;
int totalLines = 0;
boolean found = false;
// First get the total number of lines
while(sc.hasNextLine()) {
totalLines++;
sc.nextLine();
System.out.println("Line looping! For Total Lines variable.");
}
int[] lineNumbers = new int[totalLines];
int lineIndex = 0;
System.out.println("Searching in each line...");
while(sc.hasNextLine()) {
// Until the end
/* Get each of the character, I mean string from
* each of the line... */
while(sc.hasNext()) {
// Until the end of line
String characterInLine = sc.next();
if(sc.findInLine(character) != null) {
found = true;
}
}
System.out.print(sc.nextLine() + "\n");
lineNumber++;
sc.nextLine();
}
System.out.println("Searching complete, showing results...");
// All done! Now post that.
if(found) {
// Something found! :D
System.out.print("Something was found!");
} else {
// Nope didn't found a fuck!
System.out.println("Sorry, '" + character +
"' didn't match any character in file.");
}
sc.close();
}
Never mind the extra usage of variables, and arrays. I would use it in further coding if I can get the character and set the value to true.
Here is the output of this program.
Initial Stage
This is the initial stage for that. I wrote Ok in the input field, you can see Ok is the very first character in the File too.
Final Stage
This is the result after the execution.
Any help in this?

You count lines and don't restart the scanner.
boolean found = false;
// First get the total number of lines
while(sc.hasNextLine()) {
totalLines++;
sc.nextLine();
System.out.println("Line looping! For Total Lines variable.");
}
int[] lineNumbers = new int[totalLines];
int lineIndex = 0;
System.out.println("Searching in each line..."); // <------
while(sc.hasNextLine()) {
add e.g.
UPDATED from the comment
sc.close();
sc = new Scanner(file);
before the next while(sc.hasNextLine())

You need to implement a way to string your characters together and check them against your input. It appears that you don't currently have a way to do this in your code.
Try building an array of characters with your scanner, and moving through and doing a check of your input vs the indexes. Or maybe there is a way to implement the tonkenizer class achieve this.
Put remember, what you are looking for is not a character, it is a string, and you need to keep this in mind when writing your code.

When you count your lines you use while(sc.hasNextLine()).
After this loop, your scanner is behind the last line, so when you go to your next loop while(sc.hasNextLine()) { it is never executed.

There are multiple problems with your code:
You Iterated through your scanner here:
while(sc.hasNextLine()) {
totalLines++;
sc.nextLine();
System.out.println("Line looping! For Total Lines variable.");
}
So after this you have to reset it again to read for further processing.
While searching for character you are having two loops:
while(sc.hasNextLine()) {
// Until the end
/* Get each of the character, I mean string from
* each of the line... */
while(sc.hasNext()) {
// Until the end of line
String characterInLine = sc.next();
if(sc.findInLine(character) != null) {
found = true;
}
}
Here you just need a single loop like:
while(sc.hasNextLine()) {
String characterInLine = sc.nextLine();
if(characterInLine.indexOf(character) != -1) {
found = true;
break;
}
}