Thank you all very much for your help both answers work Perfectly.
I have a Lab assigment for Java that I need some help with please.
The assignemnt is to Read a txt that has 28 ints and then place them into a 2D Array.
Here is what I have:
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class TextFileExample {
public static void main(String[] args) {
String fileName = "TemperatureData.txt";
Scanner inputStream = null;
System.out.println("The file " + fileName + "\ncontains the following lines:\n");
try
{
inputStream = new Scanner(new File("C:\\Users\\username\\Documents\\TemperatureData.txt"));//The txt file is being read correctly.
String line = inputStream.nextLine();
String[] numbers = line.split("");
int[][] temperatures = new int[4][7];
for (int row = 0; row < 4; row++) {
for (int column = 0; column < 7; column++) {
temperatures[row][column] = temperatures.parseInt(temperatures[row][column]);//Is this correct?
}
}
}
catch(FileNotFoundException e)
{
System.out.println("Error opening the file " + fileName);
System.exit(0);
}
while (inputStream.hasNextLine())
{
String line = inputStream.nextLine();
System.out.println(line);
}
inputStream.close();
}
}
I need some help as to Getting the data from the txt file into the array temperatures[4][7].
Then printout the temperatures array showing the data. The output should be as follow:
Temperature Data
Week 1: 73 71 68 69 75 77 78
Week 2: 76 73 72 72 75 79 76
Week 3: 79 82 84 84 81 78 78
Week 4: 75 72 68 69 65 63 65
He does not required the txt file to be an output.
The txt file is this:
73
71
68
69
75
77
78
76
73
72
72
75
79
76
79
82
84
84
81
78
78
75
72
68
69
65
63
65
temperatures[row][column] = temperatures.parseInt(temperatures[row][column]);
Should be
temperatures[row][column] = Integer.parseInt(line);
Also, delete String[] numbers = line.split(""); as it is not used.
You need to reorder a few more things for this to work. The logic is:
Open file
if filenotfound, quit
loop through your arrays
Parse the string in the file, put it in your array
Now you can do something with the array. Note this does not elegantly handle the case where the file isn't long enough.
String fileName = "TemperatureData.txt";
Scanner inputStream = null;
System.out.println("The file " + fileName + "\ncontains the following lines:\n");
try
{
inputStream = new Scanner(new File("C:\\Users\\username\\Documents\\TemperatureData.txt"));//The txt file is being read correctly.
}
catch(FileNotFoundException e)
{
System.out.println("Error opening the file " + fileName);
System.exit(0);
}
for (int row = 0; row < 4; row++) {
for (int column = 0; column < 7; column++) {
String line = inputStream.nextLine();
int[][] temperatures = new int[4][7];
temperatures[row][column] = Integer.parseInt(line);
}
}
inputStream.close();
Here is a solution:
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.InputMismatchException;
import java.util.Scanner;
import java.util.StringTokenizer;
public class TxtTo2DArray {
public static void main(String[] args) throws FileNotFoundException, IOException {
String filename = ""; //Here you must write the path to the file f.exp "//folder//file.txt"
try{
FileReader readConnectionToFile = new FileReader(filename);
BufferedReader reads = new BufferedReader(readConnectionToFile);
Scanner scan = new Scanner(reads);
int[][] temperatures = new int[4][7];
int counter = 0;
try{
while(scan.hasNext() && counter < 5){
for(int i = 0; i < 4; i++){
counter = counter + 1;
for(int m = 0; m < 7; m++){
temperatures[i][m] = scan.nextInt();
}
}
}
for(int i = 0; i < 4; i++){
System.out.println("Temperature at week:" + (i + 1) + " is: " + temperatures[i][0] + ", " + temperatures[i][1] + ", " + temperatures[i][2] + ", " + temperatures[i][3] + ", " + temperatures[i][4] + ", " + temperatures[i][5] + ", " + temperatures[i][6]);
}
} catch(InputMismatchException e){
System.out.println("Error converting number");
}
scan.close();
reads.close();
} catch (FileNotFoundException e){
System.out.println("File not found" + filename);
} catch (IOException e){
System.out.println("IO-Error open/close of file" + filename);
}
}
}
With your file gave this results:
Temperature at week:1 is: 73, 71, 68, 69, 75, 77, 78
Temperature at week:2 is: 76, 73, 72, 72, 75, 79, 76
Temperature at week:3 is: 79, 82, 84, 84, 81, 78, 78
Temperature at week:4 is: 75, 72, 68, 69, 65, 63, 65
Related
This question already has answers here:
Reading only the integers from a txt file and adding the value up for each found
(5 answers)
Closed 5 years ago.
I'm working on a project that reads in grades from a file but the file contains student names and the class they are in as well, some have 3 grades and some have 4. I'm struggling with getting a divide by 0 error when I try to run the program and cant figure it out after much googling, beginner with java. I'm fine with opening the file but I'm struggling with how to get it to read the average of the first line then continue to all the other ones as well returning the value in the println.
File contents(with three grades):
//Happy CS145 81 85 91
//Sneezy CS145 67 75 75
//Doc CS145 92 97 89
//Dopey CS111
//Grumpy CS145 75 65 66
//Bashful CS145 81 82 81
//Sleepy CS145 71 74 71
import java.io.FileReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class MainClass {
public static void main(String args[]){
int numTestScores = 0;
int sum = 0;
int average = 0;
Scanner input = null;
try {
input = new Scanner(new File("PA2data2.txt"));
} catch (FileNotFoundException ex) {
System.out.println("Cannot open file - " + ex);
}
while (input.hasNext()) {
while (input.hasNextInt()){
sum += input.nextInt();
numTestScores++;
}
average = sum / numTestScores;
System.out.println(average);
}
System.out.println("Average is " + sum / numTestScores);
input.close();
}
}
You should use nextLine() rather than nextInt()
while (input.hasNext()) {
String line = input.nextLine();
String[] brokenLine = line.split(" ");
//do stuff with your array of {Happy, CS145, 81, 85, 91}
...
...
}
Also, your also going to want to use doubles rather than int for average, you will get average of 0 otherwise.
Just keep your division operation inside an if statement:
if(numTestScores > 0) {
average = sum / numTestScores;
System.out.println(average);
}
I have a text file and i need to read data from it to a 2D array. the file contains string as well as numbers.
String[][] arr = new String[3][5];
BufferedReader br = new BufferedReader(new FileReader("C:/Users/kp/Desktop/sample.txt"));
String line = " ";
String [] temp;
int i = 0;
while ((line = br.readLine())!= null){
temp = line.split(" ");
for (int j = 0; j<arr[i].length; j++) {
arr[i][j] = (temp[j]);
}
i++;
}
sample text file is :
name age salary id gender
jhon 45 4900 22 M
janey 33 4567 33 F
philip 55 5456 44 M
now, when the name is a single word without any space in between, the code works. but it doesn't work when the name is like "jhon desuja". How to overcome this?
I need to store it in a 2d array. how to validate the input? like name should not contain numbers or age should not be negative or contain letters. any help will be highly appreciated.
Regular Expression might be a better options:
Pattern p = Pattern.compile("(.+) (\\d+) (\\d+) (\\d+) ([MF])");
String[] test = new String[]{"jhon 45 4900 22 M","janey 33 4567 33 F","philip 55 5456 44 M","john mayer 56 4567 45 M"};
for(String line : test){
Matcher m = p.matcher(line);
if(m.find())
System.out.println(m.group(1) +", " +m.group(2) +", "+m.group(3) +", " + m.group(4) +", " + m.group(5));
}
which would return
jhon, 45, 4900, 22, M
janey, 33, 4567, 33, F
philip, 55, 5456, 44, M
john mayer, 56, 4567, 45, M
I wrote this code that was intended to read a file with integer values. If the integer values are >= 0 and <=100 I need to give the average of the grades. If there are any values out of the specified range 0-100 then I need to count the incorrect integer grades, inform the user of the incorrect grades, and inform how many incorrect grades there were. I attempted the code but I keep getting the error code:
Exception in thread "main" java.util.NoSuchElementException
at java.util.Scanner.throwFor(Unknown Source)
at java.util.Scanner.next(Unknown Source)
at Project9.main(Project9.java:26)
Code sample:
public static void main(String[] args) throws IOException{
String file;
int readInts;
Scanner k = new Scanner(System.in);
System.out.println("Enter filename: ");
file = k.nextLine();
int counterWrong = 0;
int counterRight = 0;
int sum = 0;
double average = 1.0 * sum/counterRight;
File fileReader = new File(file);
if (fileReader.exists()) {
Scanner input = new Scanner(fileReader);
while (input.hasNext()) {
readInts = input.nextInt();
System.out.println(readInts);
String a = input.next();
int a2 = Integer.parseInt(a);
if (a2 <= 100 && a2 >= 0){
counterRight++;
sum = sum + a2;
System.out.println("Score " + a2 + " was counted.");
} else {
counterWrong++;
System.out.println("The test grade " + a2 + " was not scored as it was out of the range of valid scores.");
System.out.println("There were " + counterWrong + " invalid scores that were not counted.");
}
}
if (counterRight > 0){
System.out.println("The average of the correct grades on file is " + average + ".");
}
} else {
System.out.println("The file " + file + " does not exist. The program will now close.");
}
}
}
You are doing a single check hasNext but then you read twice from scanner using nextInt() and next().
There may be two issues with your code I see.
file = k.nextLine(); // Depending on how your file is set up k.nextLine() or k.next() or maybe k.nextInt() may be useful.
while (input.hasNext()) {
readInts = input.nextInt(); // input.hasNext() assumes the next value the scanner is reading has a string value which would make readInts = input.nextInt(); impossible to use without parsing (or some other method).
I thought it'd be fun to try out this exercise (didn't want to ruin it for you). Check out my code and hopefully you'll pick up on some of the concepts I was talking about.
Note: My program reads integer values like 95 185 23 13 90 93 37 125 172 99 54 148 53 36 181 127 85 122 195 45 79 14 19 88 34 73 92 97 200 167 126 48 109 38. Which uses hasNext() & next() to get every token listed. So using nextLine() wouldn't be useful for the given input.
package cs1410;
import java.io.File;
import java.io.IOException;
import java.util.Scanner;
import javax.swing.JFileChooser;
public class Grader {
public static void main(String[] args) throws IOException {
int count = 0;
int sum = 0;
double ave = 0;
int incorrectCount = 0;
String correctGrades = "";
String incorrectGrades = "";
// Read file input
JFileChooser chooser = new JFileChooser();
if (JFileChooser.APPROVE_OPTION != chooser.showOpenDialog(null)) {
return;
}
File file = chooser.getSelectedFile();
// Scan chosen document
Scanner s = new Scanner(file);
// While the document has an Int
while (s.hasNextInt()) {
// Convert our inputs into an int
int grade = Integer.parseInt(s.next());
if (grade >= 0 && grade <= 100) {
// adds sum
sum += grade;
// increments correct count
count++;
// displays valid grades
correctGrades += Integer.toString(grade) + "\n";
} else {
// increments incorrect count
incorrectCount++;
// displays invalid grades
incorrectGrades += Integer.toString(grade) + "\n";
}
}
// Created average variable
ave = sum / count;
// bada bing bada boom
System.out.println("The number of correct grades were " + correctGrades);
System.out.println("The average score on this test was " + ave + "\n");
System.out.println("The number of incorrect grades were " + incorrectCount + "\n");
System.out.println("The incorrect values for the grades were " + "\n" + incorrectGrades);
}
}
Use hasNextInt() instead of hasNext().
hasNext() only means there is another token, not necessarily that there is another integer which you are assuming when you wrote nextInt().
Here's the documentation for hasNext() and hasNextInt()
You also want to do a check before this line:
String a = input.next();
For each student read from the file, output the following information:
Student Number (line number from the file, 1 to N)
Student Name (last name, a comma, and first name)
Student Athlete
Output Yes or No(Athlete Flag (Y = is an athlete, N = is not an athlete)
Eligibility-- Output either Yes or No --(Rule: If student is an athlete, their letter grade must be a “C” or higher to be eligible to play in the big game)
**this is how the text file looks:
Smith Richard N 87 98 59 77 77 92 86
Johnson Daniel Y 73 56 83 82 69 72 61
Williams David N 60 70 91 56 70 71 77
Jones Carol N 88 85 76 68 61 84 98
Brown James Y 67 91 62 73 74 83 94
Davis Dorothy N 96 60 97 58 82 100 89
Miller Jeff N 80 74 74 68 64 90 87
Wilson William N 61 83 96 59 67 68 60
Moore Betty N 65 59 93 86 72 80 73
Taylor Helen N 94 77 83 68 80 60 73
Anderson Sandra N 78 94 91 95 88 70 75
Each Row of the Text File Contains:
• Student Last Name
• Student First Name
• Athlete Flag (Y = is an athlete, N = is not an athlete)
• Grade on Quiz 1
• Grade on Quiz 2
• Grade on Quiz 3
• Grade on Quiz 4
• Grade on Quiz 5
• Grade on Test 1
• Grade on Test 2
This is i have written so far,
import java.io.*;
import java.util.*;
public class Assignment3
{
public static final void main(String args[]) throws FileNotFoundException
{
System.out.println("my name!");
Scanner myScanner = new Scanner(new File("students.txt"));
String firstName = myScanner.next();
String lastName = myScanner.next();
String athlete=myScanner.next();
int lineNumber =1;
while (myScanner.hasNextLine())
{
if(myScanner.hasNextLine())
{
myScanner.nextLine();
}
System.out.println(lineNumber + " "+ lastName + ", "+ firstName +
athlete);
String firstName = myScanner.next();
String lastName = myScanner.next();
String athlete=myScanner.next();
lineNumber++;
}
}
}
I am really new to java. can anyone help please?
You can try for this code snippet, I didn’t get your question properly. But it's better to use BufferedReader instead of Scanner
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
public class Assignment3 {
public static void main(String[] args) {
try (BufferedReader br = new BufferedReader(new FileReader("C:\\students.txt"))) {
String line;
int lineNumber = 1;
while ((line = br.readLine()) != null) {
System.out.println(line);
String[] words = line.split(" ");
if (words.length <= 1) {
continue;
}
String studentNumber = ""+ lineNumber++;
String studentName = words[1]+","+words[0];
String studentAthlete = words[2];
boolean eligibility = false;
if(studentAthlete.equals("Y")){
int totalMarks = 0;
int subject = words.length-3;
for (int i = 3; i < subject; i++) {
totalMarks+= Integer.parseInt(words[i]);
}
int marksGrade = totalMarks/subject;
// now you can check the grade
if(marksGrade<50){
eligibility = true;
}
}
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
I am trying to get the averages of values in a text file. The content of the file is:
Agnes 56 82 95 100 68 52
Bufford 87 92 97 100 96 85 93 77 98 86
Julie 99 100 100 89 96 100 92 99 68
Alice 40 36 85 16 0 22 72
Bobby 100 98 92 86 88
I have to skip the names, and try to sum the values of the integers of each line. The ouput should be something like this:
Agnes, average = 76
Bufford, average = 91
Julie, average = 94
Alice, average = 39
Bobby, average = 93
My problem is that i am unable to sum the values (using sum+=sc1.nextInt()). I also cant count the number of tokens of just the integers. For example, for the first line I need countTokens to equal 6, but i get 7, even after I skip the name.
import java.io.*;
import java.util.*;
public class studentAverages
{
public static void main() throws IOException
{
Scanner sf = new Scanner(new File("C:\\temp_Name\\StudentScores.in"));
int maxIndex = -1;
String text[] = new String[100];
while(sf.hasNext( ))
{
maxIndex++;
text[maxIndex] = sf.nextLine();
}
sf.close();
int sum=0;
int avg=0;
int divisor=0;
for (int i=0;i<=maxIndex; i++)
{
StringTokenizer sc= new StringTokenizer(text[i]);
Scanner sc1= new Scanner (text[i]);
while (sc1.hasNext())
{
sc1.useDelimiter(" ");
sc1.skip("\\D*");
System.out.print(sc1.nextInt());
System.out.println(sc1.nextLine());
sum+=sc1.nextInt(); // trying to sum all the numbers in each line, tried putting this line everywhere
avg=sum/divisor;
break;
}
System.out.println(avg);
while (sc.hasMoreTokens())
{
divisor=sc.countTokens()-1; //Not able to count tokens of just the numbers, thats why I am using -1
//System.out.println(divisor);
break;
}
}
//this is for the output
/*for (int i=0; i<=maxIndex; i++)
{
String theNames="";
Scanner sc= new Scanner (text[i]);
theNames=sc.findInLine("\\w*");
System.out.println(theNames + ", average = ");
}*/
}
}
I would recommend splitting each line using the split method and then looping through those values while ignoring the first, because you know that is the title.
public static void main() throws IOException {
Scanner sf = new Scanner(new File("C:\\temp_Name\\StudentScores.in"));
int maxIndex = -1;
String text[] = new String[100];
while(sf.hasNext( )) {
maxIndex++;
text[maxIndex] = sf.nextLine();
}
sf.close();
for(int i = 0; i < maxIndex; i ++) {
String[] values = text[i].split(" ");
String title = values[0];
int sum = 0;
for(int j = 1; i < values.length; j ++) {
sum += Integer.parseInt(values[j]);
}
double average = sum / (values.length - 1);
System.out.println(title + ": " + average);
}
}
Notice that the inner loop's index begins at 1 and not 0, and that when calculating the average, we subtract one from the size of the values array because we want to ignore the title.
Try this one:
Scanner scanner = new Scanner(new File("resources/abc.txt"));
//check for next line
while (scanner.hasNextLine()) {
//create new scanner for each line to read string and integers
Scanner scanner1 = new Scanner(scanner.nextLine());
//read name
String name = scanner1.next();
double total = 0;
int count = 0;
//read all the integers
while (scanner1.hasNextInt()) {
total += scanner1.nextInt();
count++;
}
System.out.println(name + ", average = " + (total / count));
}
scanner.close();
output:
Agnes, average = 75.5
Bufford, average = 91.1
Julie, average = 93.66666666666667
Alice, average = 38.714285714285715
Bobby, average = 92.8
--EDIT--
Here is the code as per your last comment (I have to use StringTokenizer`/string methods like useDelimiter, skip, etc to arrive at the answer)
Scanner sf = new Scanner(new File("resources/abc.txt"));
List<String> text = new ArrayList<String>();
while (sf.hasNext()) {
text.add(sf.nextLine());
}
sf.close();
for (String str : text) {
StringTokenizer sc = new StringTokenizer(str, " ");
double sum = 0;
int count = 0;
String name = sc.nextToken();
while (sc.hasMoreElements()) {
sum += Integer.valueOf(sc.nextToken());
count++;
}
System.out.println(name + ", average = " + (sum / count));
}
}
output
Agnes, average = 75.5
Bufford, average = 91.1
Julie, average = 93.66666666666667
Alice, average = 38.714285714285715
Bobby, average = 92.8