I would like some help with a project that I am working on. I want to create a simple program that formats data into a way that is accepting of our database. I am having trouble copying the contents of the main file to the destination file. The program creates the new destination file and it writes the "Gage ID, Date/Time, Precip_1min, Precip/Year" headers in the file but there are no data values copied to the new file. I have tried to look online for some solutions but, I have had no luck in applying these solutions. The main thing that I am concentrating on is copying each line of the main file to the new created file one-by-one then I will work from there. Any assistance is very much appreciated! Here is my code so far. P.S Cowlic105.txt is the file that has the lines of data that I want to be copied.
import java.io.*;
import java.util.Scanner;
public class MyDataFormat {
public static void main(String[] args) {
String fileName = "Cowlic105.txt";
String fileName2 = "FormDatFile.txt";
String line = null;
int x;
int gageID;
int precipYTD;
try {
FileReader fileReader = new FileReader(fileName);
BufferedReader bufferedReader = new BufferedReader(fileReader);
while((line = bufferedReader.readLine()) != null) {
System.out.println(line);
}
bufferedReader.close();
}
catch(FileNotFoundException ex) {
System.out.println("Unable to open file '" + fileName + "'");
}
catch(IOException ex) {
System.out.println("Error reading file '" + fileName + "'");
}
Scanner in = new Scanner(System.in);
System.out.println("Is this the file you wish to format? " + fileName + "(0 for no, 1 for yes)");
x = in.nextInt();
if (x == 0){
System.exit(0);
}
else if (x == 1){
System.out.println("Hello there you resumed the program!!!");
System.out.println("What is the ID of the rain gage? ");
gageID = in.nextInt();
System.out.println("What is the value of precipitation YTD? ");
precipYTD = in.nextInt();
File destFile = new File("FormDatFile.txt");
if(!destFile.exists()){
try {
destFile.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
try {
FileInputStream fis = new FileInputStream(destFile);
FileWriter writer = new FileWriter(destFile, true);
BufferedWriter write2 = new BufferedWriter(writer);
FileReader fileReader = new FileReader(fileName);
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(fis));
while((line = bufferedReader.readLine()) != null){
write2.write(line);
write2.newLine();
bufferedReader.close();
write2.close();
}
writer.write("Gage ID,Date/Time,Precip_1min,Precip/Year");
writer.write("\r\n");
writer.close();
}
catch (IOException e){
e.printStackTrace();
}
}
}
}
I am trying to make a program that imports a text file and analyzes it to tell me if another text file has possible match up sentences. I keep running into this error when I import my file and attempt to analyze it. I am assuming that I am missing something in my code.
Exception in thread "main" java.util.NoSuchElementException
at java.util.Scanner.throwFor(Scanner.java:907)
at java.util.Scanner.next(Scanner.java:1416)
at PossibleSentence.main(PossibleSentence.java:30)
Heres my code too:
import java.util.Scanner;
import java.io.File;
import java.io.FileNotFoundException;
public class PossibleSentence {
public static void main(String[] args) throws FileNotFoundException{
Scanner testScan = new Scanner(System.in);
System.out.print("Please enter the log file to analyze: ");
String fileName = testScan.nextLine();
File f = new File(fileName);
Scanner scan = new Scanner(f);
String line = null;
int i = 0;
while (scan.hasNextLine()) {
String word = scan.next();
i++;
}
scan.close();
File comparative = new File("IdentifyWords.java");
Scanner compare = new Scanner(comparative);
String line2 = null;
}
}
The second scanner I havent completed yet either. Any suggestions?
We need more info to conclusively answer, but check out the documentation for next(). It throws this exception when there's no next element. My guess is it's because of this part:
String fileName = testScan.nextLine();
You're not checking if hasNextLine first.
You are passing a file argument to a Scanner object, try using an InputStream
File input = new File(/* file argument*/);
BufferedReader br = null;
FileReader fr= null;
Scanner scan = null;
try {
fr = new FileReader(input);
br = new BufferedReader(fr);
scan = new Scanner(br);
/* Do logic with scanner */
} catch (IOException e) {
/* handling for errors*/
} finally {
try {
if (br != null) {
br.close();
}
if (fr != null) {
fr.close();
}
if (scan != null) {
scan.close();
}
} catch (IOException e) {
/* handle closing error */
}
}
This is my question :
a method readLine that reads a line from the file specified in fileName and returns the line a String.
What I am trying to do is I read and write some info into text file using eclipse. And here are my codes :
public class FileController {
private String fileName;
public FileController(){
String fileName = "student.txt";
}
public FileController(String fileName){
this.fileName = fileName;
}
public String readLine(){
String line ="";
try{
FileReader fr = new FileReader(fileName);
Scanner sc = new Scanner(fr);
while(sc.hasNextLine()){
Student stud = new Student(sc.nextLine());
line = stud.toString();
}
fr.close();
}catch(FileNotFoundException exception){
System.out.println("File " + fileName + " was not found");
}catch(IOException exception){
System.out.println(exception);
}
return line;
}
public void writeLine(String input){
try{
FileWriter fw = new FileWriter(fileName,true);
BufferedWriter bw = new BufferedWriter(fw);
PrintWriter outFile = new PrintWriter(bw);
outFile.println(input);
outFile.close();
}catch(IOException exception){
System.out.println(exception);
}
}
public static void main (String [] args){
FileController fc = new FileController("student.txt");
String input = "1234567H;Gabriel;23/12/1994;56;67;87";
fc.readLine();
fc.writeLine(input);
}
This works perfectly by adding the record into the text file. However, the console there doesn't shows the result. So from what I know it's the mistake was at readLine(). When I used void it works perfectly. But the question requests me to return a String. Anybody know how to solve this?
when I do println within the while loop there's record stored in there. I guess the programme took the String file= ""; this line and return the result. So how can I take the result of line in while loop and replace with the initialization?
You are overwriting the line in while loop:
try{
FileReader fr = new FileReader(fileName);
Scanner sc = new Scanner(fr);
while(sc.hasNextLine()){
Student stud = new Student(sc.nextLine());
line = stud.toString();
}
So this means that only last line will get passed to student [most likely blank line] and it might not print anything or even an exception might come. Use StringBuffer and append the string and then return that.
EDIT:
Try this.
public String readLine(){
StringBuffer line =new StringBuffer();
try{
FileReader fr = new FileReader(fileName);
Scanner sc = new Scanner(fr);
while(sc.hasNextLine()){
Student stud = new Student(sc.nextLine());
line.append(stud.toString());
}
fr.close();
}catch(FileNotFoundException exception){
System.out.println("File " + fileName + " was not found");
}catch(IOException exception){
System.out.println(exception);
}
return line.toString();
}
EDIT:
If above code also returns blank then most likely issue is Strudent "toString()" method. It might be returning blank.
EDIT:
public String readLine(){
StringBuffer line =new StringBuffer();
try{
FileReader fr = new FileReader(fileName);
Scanner sc = new Scanner(fr);
while(sc.hasNextLine()){
Student stud = new Student(sc.nextLine());
line.append(stud.toString());
line.append("\n");
}
fr.close();
}catch(FileNotFoundException exception){
System.out.println("File " + fileName + " was not found");
}catch(IOException exception){
System.out.println(exception);
}
return line.toString();
}
I have a problem with BufferReader and OutputStream in Java. My aim: when you insert something from a keyboard - it goes to the file. How should I correct my code?
import java.io.*;
class IntoFile {
public static void main(String[] args) throws Exception{
try {
BufferedReader sisse = new BufferedReader(new InputStreamReader(System.in));
System.out.print ("Insert something: ");
String s = sisse.readLine();
byte[] buf = new byte[1024];
OutputStream valja = new FileOutputStream(new File(args[0]));
String line = null;
while ((line = br.readLine()) != null) {
}
valja.close();
}
catch (IOException e) {
System.out.println ("I/O: " + e);
}
}
}
Thanks!
I'd use Scanner and PrintWriter
C:\Documents and Settings\glowcoder\My Documents>javac Dmitri.java
C:\Documents and Settings\glowcoder\My Documents>java Dmitri
test
woohoo
quit
C:\Documents and Settings\glowcoder\My Documents>more out.txt
test
woohoo
quit
C:\Documents and Settings\glowcoder\My Documents>
Code:
import java.io.*;
import java.util.*;
class Dmitri {
public static void main(String[] args) throws Exception {
Scanner in = new Scanner(System.in);
PrintWriter out = new PrintWriter("out.txt");
while(in.hasNextLine()) {
String line = in.nextLine();
out.println(line);
out.flush(); // not necessary every time, but simple to do so
if(line.equalsIgnoreCase("QUIT")) break;
}
out.close();
}
}
HI I am providing a sample code through which you can write in the file after user enters characters or line from keyboard.
try{
// Create file
FileWriter fstream = new FileWriter("out.txt");
BufferedWriter out = new BufferedWriter(fstream);
out.write("Hello Java");
//Close the output stream
out.close();
}catch (Exception e){//Catch exception if any
System.err.println("Error: " + e.getMessage());
}
In the our.write pass the line(variable) string argument and the string will be written in that file.
I need to read a text file line by line using Java. I use available() method of FileInputStream to check and loop over the file. But while reading, the loop terminates after the line before the last one. i.e., if the file has 10 lines, the loop reads only the first 9 lines.
Snippet used :
while(fis.available() > 0)
{
char c = (char)fis.read();
.....
.....
}
You should not use available(). It gives no guarantees what so ever. From the API docs of available():
Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next invocation of a method for this input stream.
You would probably want to use something like
try {
BufferedReader in = new BufferedReader(new FileReader("infilename"));
String str;
while ((str = in.readLine()) != null)
process(str);
in.close();
} catch (IOException e) {
}
(taken from http://www.exampledepot.com/egs/java.io/ReadLinesFromFile.html)
How about using Scanner? I think using Scanner is easier
private static void readFile(String fileName) {
try {
File file = new File(fileName);
Scanner scanner = new Scanner(file);
while (scanner.hasNextLine()) {
System.out.println(scanner.nextLine());
}
scanner.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
Read more about Java IO here
If you want to read line-by-line, use a BufferedReader. It has a readLine() method which returns the line as a String, or null if the end of the file has been reached. So you can do something like:
BufferedReader reader = new BufferedReader(new InputStreamReader(fis));
String line;
while ((line = reader.readLine()) != null) {
// Do something with line
}
(Note that this code doesn't handle exceptions or close the stream, etc)
String file = "/path/to/your/file.txt";
try {
BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(file)));
String line;
// Uncomment the line below if you want to skip the fist line (e.g if headers)
// line = br.readLine();
while ((line = br.readLine()) != null) {
// do something with line
}
br.close();
} catch (IOException e) {
System.out.println("ERROR: unable to read file " + file);
e.printStackTrace();
}
You can try FileUtils from org.apache.commons.io.FileUtils, try downloading jar from here
and you can use the following method:
FileUtils.readFileToString("yourFileName");
Hope it helps you..
The reason your code skipped the last line was because you put fis.available() > 0 instead of fis.available() >= 0
In Java 8 you could easily turn your text file into a List of Strings with streams by using Files.lines and collect:
private List<String> loadFile() {
URI uri = null;
try {
uri = ClassLoader.getSystemResource("example.txt").toURI();
} catch (URISyntaxException e) {
LOGGER.error("Failed to load file.", e);
}
List<String> list = null;
try (Stream<String> lines = Files.lines(Paths.get(uri))) {
list = lines.collect(Collectors.toList());
} catch (IOException e) {
LOGGER.error("Failed to load file.", e);
}
return list;
}
//The way that I read integer numbers from a file is...
import java.util.*;
import java.io.*;
public class Practice
{
public static void main(String [] args) throws IOException
{
Scanner input = new Scanner(new File("cards.txt"));
int times = input.nextInt();
for(int i = 0; i < times; i++)
{
int numbersFromFile = input.nextInt();
System.out.println(numbersFromFile);
}
}
}
Try this just a little search in Google
import java.io.*;
class FileRead
{
public static void main(String args[])
{
try{
// Open the file that is the first
// command line parameter
FileInputStream fstream = new FileInputStream("textfile.txt");
// Get the object of DataInputStream
DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String strLine;
//Read File Line By Line
while ((strLine = br.readLine()) != null) {
// Print the content on the console
System.out.println (strLine);
}
//Close the input stream
in.close();
}catch (Exception e){//Catch exception if any
System.err.println("Error: " + e.getMessage());
}
}
}
Try using java.io.BufferedReader like this.
java.io.BufferedReader br = new java.io.BufferedReader(new java.io.InputStreamReader(new java.io.FileInputStream(fileName)));
String line = null;
while ((line = br.readLine()) != null){
//Process the line
}
br.close();
Yes, buffering should be used for better performance.
Use BufferedReader OR byte[] to store your temp data.
thanks.
user scanner it should work
Scanner scanner = new Scanner(file);
while (scanner.hasNextLine()) {
System.out.println(scanner.nextLine());
}
scanner.close();
public class ReadFileUsingFileInputStream {
/**
* #param args
*/
static int ch;
public static void main(String[] args) {
File file = new File("C://text.txt");
StringBuffer stringBuffer = new StringBuffer("");
try {
FileInputStream fileInputStream = new FileInputStream(file);
try {
while((ch = fileInputStream.read())!= -1){
stringBuffer.append((char)ch);
}
}
catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println("File contents :");
System.out.println(stringBuffer);
}
}
public class FilesStrings {
public static void main(String[] args) throws FileNotFoundException, IOException {
FileInputStream fis = new FileInputStream("input.txt");
InputStreamReader input = new InputStreamReader(fis);
BufferedReader br = new BufferedReader(input);
String data;
String result = new String();
while ((data = br.readLine()) != null) {
result = result.concat(data + " ");
}
System.out.println(result);
File file = new File("Path");
FileReader reader = new FileReader(file);
while((ch=reader.read())!=-1)
{
System.out.print((char)ch);
}
This worked for me
Simple code for reading file in JAVA:
import java.io.*;
class ReadData
{
public static void main(String args[])
{
FileReader fr = new FileReader(new File("<put your file path here>"));
while(true)
{
int n=fr.read();
if(n>-1)
{
char ch=(char)fr.read();
System.out.print(ch);
}
}
}
}