Reading a file object in Java - java

How do you read a file object in java?
File file= new File(filePathName);
if (file.exists()){
filesArrayList.add(file);
}
Depending on the number of processors threads are sent:
a file and a starting (lower bound) and end (upper bound) to read.
File inputFile= (File)filesArrList.get(i);
BufferedInputStream bis= new BufferedInputStream(new FileInputStream (inputFile));
while ((line=bis.readLine())!=null) {
System.out.println(line);
}
Is it possible to read the files in the arraylist?

1 : You can read files stored in ArrayList through the following way.
2 : Yes it is also possible to read files stored in array list.
public class ReadingFiles {
BufferedReader br;
ArrayList<File> list = new ArrayList<>();
ReadingFiles() {
list.add(new File((getClass().getResource("file1.txt")).getPath()));
readFile(list.get(0));
list.add(new File((getClass().getResource("file2.txt")).getPath()));
readFile(list.get(1));
}
public void readFile(File file) {
try {
br = new BufferedReader(new FileReader(file));
String line = br.readLine();
while (line != null) {
System.out.println(line);
line = br.readLine();
}
br.close();
} catch (Exception ex) {
System.out.println("Sorry");
}
}
public static void main(String[] args){
new ReadingFiles();
}
}

Related

String cannot be converted to array

I have a program that reads in a file using a filename specified by the user.
All file contents must be read and stored in the array. I seem to have done the IO Correctly besides this error. I understand what the error is but not sure how to correct.
EDIT: The array is already defined in the file.
Zoo.java:284: error: incompatible types: String cannot be converted to
Animals
animals[ j ] = bufferedReader.readLine();
Here is my code for the readFile Submodule:
public String readFile(Animals[] animals)
{
Scanner sc = new Scanner(System.in);
String nameOfFile, stringLine;
FileInputStream fileStream = null;
BufferedReader bufferedReader;
InputStreamReader reader;
System.out.println("Please enter the filename to be read from.");
nameOfFile = sc.nextLine();
try
{
constructed = true;
fileStream = new FileInputStream(nameOfFile);
bufferedReader = new BufferedReader(new InputStreamReader(fileStream));
while((stringLine = bufferedReader.readLine()) != null)
{
for(int j = 0; j < animals.length; j++)
{
animals[j] = bufferedReader.readLine();
}
}
fileStream.close();
}
catch(IOException e)
{
if(fileStream != null)
{
try
{
fileStream.close();
}
catch(IOException ex2)
{
}
}
System.out.println("Error in file processing: " + e.getMessage();
}
}
Thanks for the help.
animals is array of Animals, but bufferedReader.readLine() reads line. You should convert it to Animal. I don't see definition of your class Animals, but, I think, there should be constructor that takes String as argument.
So, If i'm right, you should basically write:
animals[j] = new Animals(bufferedReader.readLine());
Lots of problems in your code. Starting with the method's input. Also reading from file.
public static void main(String[] args) {
// TODO code application logic here
for(String entry : readFile())
{
System.out.println(entry);
}
}
static public String[] readFile()
{
Scanner sc = new Scanner(System.in);
InputStreamReader reader;
System.out.println("Please enter the filename to be read from.");
String nameOfFile = sc.nextLine();
try(BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream(nameOfFile))); )
{
//constructed = true; why?
String stringLine;
ArrayList<String> arraylist = new ArrayList();
while((stringLine = bufferedReader.readLine()) != null)
{
arraylist.add(stringLine);
}
return arraylist.toArray(new String[0]);
}
catch (FileNotFoundException ex)
{
Logger.getLogger(Filetoarray.class.getName()).log(Level.SEVERE, null, ex);
}
catch (IOException ex)
{
Logger.getLogger(Filetoarray.class.getName()).log(Level.SEVERE, null, ex);
}
return null;
}

Concatenate multiple files

I am trying to concatenate multiple text files. The program is working correctly, but if I do not know the total number of files, then how should the for loop be changed?
public class MultipleMerge {
public static void main(String[] args) {
BufferedReader br = null;
BufferedWriter bw = null;
String inFileName = "C:\\Users\\dokania\\Desktop\\Bio\\Casp10\\fasta\\out";
File file = new File("C:\\Users\\dokania\\Desktop\\New folder\\out.txt");
try {
String s;
int fileCounter = 0;
FileWriter fw = new FileWriter(file.getAbsoluteFile());
bw = new BufferedWriter(fw);
for (fileCounter = 0; fileCounter < 157; fileCounter++) {
br = new BufferedReader(new FileReader(inFileName + (fileCounter++) + ".fa"));
while ((s = br.readLine()) != null) {
bw.write(s + "\n");
}
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (br != null) {
br.close();
bw.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
Try get an array of Files in directory:
File[] array = new File("C:\\Users\\dokania\\Desktop\\Bio\\Casp10\\fasta\\").listFiles();
And then go through all files using foreach cycle
for(File file:array){
//...
}
Maybe you'll need to use FileFilter:
http://docs.oracle.com/javase/7/docs/api/java/io/FileFilter.html
in method listFiles()
You could use command line arguments:
public class CommandLineTest {
public static void main(String[] args) {
int howManyFiles = Integer.parseInt(args[0]);
}
}
Above code gives you the first command line argument and treats it as an integer. In your code, you should check if there really is an integer specified, though.

Java read large text file with separator

I'm trying to read a large text file in the form of:
datadfqsjmqfqs+dataqfsdqjsdgjheqf+qsdfklmhvqziolkdsfnqsdfmqdsnfqsdf+qsjfqsdfmsqdjkgfqdsfqdfsqdfqdfssdqdsfqdfsqdsfqdfsqdfs+qsfddkmgqjshfdfhsqdflmlkqsdfqdqdf+
I want to read this string in the text file as one big java String. Is this possible? I know the use of the split method.
It worked to read it line by line, but what I really need is to split this long text-string at the '+' sign. Afterwards I want to store it as an array, arraylist, list,...
Can anyone help me with this? Because every information on the internet is just about reading a file line by line.
Thanks in advance!
String inpStr = "datadfqsjmqfqs+dataqfsdqjsdgjheqf+qsdfklmhvqziolkdsfnqsdfmqdsnfqsdf+qsjfqsdfmsqdjkgfqdsfqdfsqdfqdfssdqdsfqdfsqdsfqdfsqdfs+qsfddkmgqjshfdfhsqdflmlkqsdfqdqdf+";
String[] inpStrArr = inpStr.split("+");
Hope this is what you need.
You can read file using BufferedReader or any IO-classes.suppose you have that String in testing.txt file then by reading each line from file you can split it by separator (+). and iterate over array and print.
BufferedReader br = null;
try {
String sCurrentLine;
br = new BufferedReader(new FileReader("C:\\testing.txt"));//file name with path
while ((sCurrentLine = br.readLine()) != null) {
String[] strArr = sCurrentLine.split("\\+");
for(String str:strArr){
System.out.println(str);
}
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (br != null)br.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}
It seems to me like your problem is that you don't want to read the file line by line. So instead, try reading it in parts (say 20 characters each time and building your string):
char[] c = new char[20]; //best to save 20 as a final static somewhere
ArrayList<String> strings = new ArrayList<String>();
StringBuilder sb = new StringBuilder();
BufferedReader br = new BufferedReader(new FileReader(filename));
while (br.read(c) == 20) {
String str = new String(c);
if (str.contains("+") {
String[] parts = str.split("\\+");
sb.append(parts[0]);
strings.add(sb.toString());
//init new StringBuilder:
sb = new StringBuilder();
sb.add(parts[1]);
} else {
sb.append(str);
}
}
You should be able to get a String of length Integer.MAX_VALUE (always 2147483647 (231 - 1) by the Java specification, the maximum size of an array, which the String class uses for internal storage) or half your maximum heap size (since each character is two bytes), whichever is smaller
How many characters can a Java String have?
Try this one:
private static void readLongString(File file){
ArrayList<String> list = new ArrayList<String>();
StringBuilder builder = new StringBuilder();
int r;
try{
InputStream in = new FileInputStream(file);
Reader reader = new InputStreamReader(in);
while ((r = reader.read()) != -1) {
if(r=='+'){
list.add(builder.toString());
builder = new StringBuilder();
}
builder.append(r);
}
}catch (IOException ex){
ex.printStackTrace();
}
for(String a: list){
System.out.println(a);
}
}
Here is one way, caveat being you can't load more than the max int size (roughly one GB)
FileReader fr=null;
try {
File f=new File("your_file_path");
fr=new FileReader(f);
char[] chars=new char[(int)f.length()];
fr.read(chars);
String s=new String(chars);
//parse your string here
} catch (Exception e) {
e.printStackTrace();
}finally {
if(fr!=null){
try {
fr.close();
} catch (IOException e) {
}
}
}

Put .txt file data in array

I'm new at java I would like to know how to read a .txt file and then put every single line in an array cell.
.txt file must be formatted as shown:
car //goes in array[0]
boat //goes in array[1]
ship //goes in array[2]
airplane //goes in array[3]
//...and so on..
I've already tried to create a ReadFile class implemented in this way:
import java.io.*;
import java.util.*;
public class ReadFile {
private Scanner x;
public void open(){
try{
x = new Scanner(new File("time_table_data.txt"));
}catch(Exception e){
System.out.println("Could Not Create The File");
}
}
public String read(){
String s = "";
while(x.hasNext()){
String a = x.next();
s = a.format("%s\n",a);
}
return s;
}
public void close(){
x.close();
}
}
The problem is that you don't know how many words there are coming. To solve that, you could use an ArrayList.
List<String> entries = new ArrayList<String>();
while (scanner.hasNext())
{
entries.add(scanner.nextLine());
}
System.out.println(entries);
Access them using the get(int index) method:
String test = entries.get(0); // This will be "car"
if you're willing to use Apache Commons IO then you can do this really easy:
import org.apache.commons.io.FileUtils;
String[] linesArr = new String[0];
List<String> lines = FileUtils.readLines(new File("FILE_NAME.txt"));
if (lines != null) {
linesArr = lines.toArray(linesArr);
}
Just do:
List<String> lines = new ArrayList<String>();
try (BufferedReader br = new BufferedReader(new FileReader(file))) {
String line;
while ((line = br.readLine()) != null) {
lines.add(line); // Add line to list
}
} // Try-with-resources closes reader
You don't need the scanner or anything else fancy when you just looking for whole lines.
If you really need an array not a list at the end you can just read out the array from the final List.
Make a method that reads all data from file and stores in a List as follows.
public ArrayList<String> fileRead(String fileName){
File f;
String s;
FileReader fr = null;
BufferedReader br = null;
ArrayList<String> sl = new ArrayList<String>();
try {
f = new File(fileName);
fr = new FileReader(f);
br = new BufferedReader(fr);
while((s=br.readLine())!=null){
sl.add(s);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}finally{
try {
if(br!=null)
br.close();
if(fr!=null)
fr.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sl;
}

Read data from a text file using Java

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);
}
}
}
}

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