So I wrote this file reader method that should return a string of everything that is in the file, but it isn't working properly. Writing into the file works perfectly, but this reading method doesn't. What the method does currently is it reads the last string/text added, but it does not read the file from start to finish. 'br' is my bufferedReader, which is declared somewhere else in the same class.
Here's how br is defined:
private static FileInputStream fis;
private static BufferedReader br;
and then in the constructor:
fis = new FileInputStream(file);
br = new BufferedReader(new InputStreamReader(fis));
Here's the method:
public String readStuff(){
String line = "";
String r = "";
try{
while((line = br.readLine()) != null){
System.out.println(line + " read ");
r+= line;
}
//br.close(); JDK 7 does this automatically apparently
}catch(IOException e){
e.printStackTrace();
System.out.println("Error at readStuff!");
}
return r;
I know I'm making either a logic mistake or some obvious error, I just don't know where.
If you want to read the entire file twice, you will have to close it and open new streams/readers next time.
Those streams/readers should be local to the method, not members, and certainly not static.
Using File and FileReader You can Read / Write File From Dir.
you can get File using File class object
File file = new File("file.txt");
and After Process to read that file
FileReader fr = new FileReader(file);
There are Whole Code to read File...
File file = new File("G:\\Neon\\data.txt");
FileReader fr = new FileReader(file);
String data = "";
while((i = fr.read()) != -1)
{
data = data + (char)i;
}
System.out.println(data);
Related
I have a situation where i have a txt file and java file bundled inside jar. I am reading txt file from java which is bundled inside jar only.
While reading file, getting FileNotFoundException in Java and where as txt file is in same folder bundled inside jar.
I am calling this Java method from a test class sample code.
public static void loadtxtfile(){
try {
InputStream in =
Utils.class.getClassLoader().getResourceAsStream("sample.txt");
File f = new File(JetUtils.class.getClassLoader().getResource("dd.js").getFile());
//OJetBase.class.getClassLoader().getResourceAsStream("logging.properties");
BufferedReader input = new BufferedReader(new FileReader(js_filepath));
StringBuffer buffer = new StringBuffer();
while ((text = input.readLine()) != null)
buffer.append(text + "\n");
java_script = buffer.toString();
}
Test call - Utils.loadtxtfile();
I tried all the options.
You cannot read resources from a jar file as a java.io.File object because they do not exist in a file system. Just use java.lang.Classloader.getResourceAsStream(String name):
Reader inputStreamReader = new InputStreamReader(
JetUtils.class.getClassLoader().getResourceAsStream("dd.js"));
BufferedReader jsReader = new BufferedReader(inputStreamReader);
StringBuilder javascript = new StringBuilder();
String input;
while ((input = jsReader.readln()) != null) {
javascript.append(input);
}
I am create a new file
File f = new File(file_path);
then the end of program can i possible to close that the file object or file?
f.close();
else there is a method is possible to close file??
public class etest2read {
public static void main(String[] args) throws IOException {
File dir = new File("input");
String source = dir.getCanonicalPath() + File.separator + "TestFile.txt";
//String TestFileone = dir.getCanonicalPath() + File.separator + "TestFileone.txt";
File fin = new File(source);
FileInputStream fis = new FileInputStream(fin);
BufferedReader br = new BufferedReader(new InputStreamReader(fis));
System.out.println("file/folder: "+fin.getAbsolutePath());
System.out.println("file/folder: "+dir.getCanonicalPath());
System.out.println("file/folder: "+fin.lastModified());
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
br.close();
System.out.println("Closed Buffered Reader");
fis.close();
System.out.println("Closed File Input Stream");
fin.close(); // providing the error
}
}
No it is not possible.
A File is an abstract representation of a file or directory pathname. You do not open the File, only a Stream or a Reader on that File.
No. You can only close the instances of objects that implement the Closeable interface (example Reader , InputStream etc). File class doesn't implement Closeable. Like Burkahard says, it is merely an abstract representation of the underlying file/ directory
I need to read contents of a file as a server, and then send the read data file, for the client so the client print it out on the Client terminal.
The problem is that I can't find a way or method to read a txt file from the current directory which my java file and txt file are existed.
Please help me.
There are many ways to read text file or file in java. It depend on you to that in which format you need to pass your file content to client side.
Here are some method to reading file in java.
1. Using BufferedReader class
BufferedReader input = new BufferedReader(new FileReader(aFile));
String line = null; //not declared within while loop
while (( line = input.readLine()) != null){
String curLine = line;
//Process line
}
2.Using Apache Common IOUtils with the class IOUtils.toString() method.
FileInputStream inputStream = new FileInputStream("FILEPATH/FILENAME");
try {
String everything = IOUtils.toString(inputStream);
} finally {
inputStream.close();
}
3.Using the Scanner class in Java and the FileReader
Scanner in = new Scanner(new FileReader("FILENAME/FILEPATH"));
while (scanner.hasNextLine()){
//process each line in some way
String line = scanner.nextLine();
}
Scanner has several methods for reading in strings, numbers, etc...
4.In JAVA 7 this is the best way to simply read a textfile
new String(Files.readAllBytes(...))
or Files.readAllLines(...)
Path path = Paths.get("FILENAME");
List<String> allLines = Files.readAllLines(path, ENCODING);
Please refer this link for more onfomation.
You can use BufferedReader to read from a txt file.
BufferedReader br = new BufferedReader(new FileReader(fileName));
String line = br.readLine();
here fileName is a string that contain your absolute file name.
eg : fileName = "C:\temp\test.txt";
You can read file by using BufferedReader.
File file=new File("filepath");
BufferedReader br=new BufferedReader(new FileReader(file)); //Here you create an object of bufferedreader which file read through filereader
String data=br.readLine();
while(data!=null)
{
System.out.println(data); // Writing in the console
data=br.readLine();
}
This will taking input from file and giving output to console.If you want it write in other file then use BufferedWriter.
File out=new File("outputfilepath");
BufferedWriter bw=new BufferedWriter(new FileWriter(out));
simply us bw.write() instead of System.out.println();.
How would I read a .txt file in Java and put every line in an array when every lines contains integers, strings, and doubles? And every line has different amounts of words/numbers.
I'm a complete noob in Java so sorry if this question is a bit stupid.
Thanks
Try the Scanner class which no one knows about but can do almost anything with text.
To get a reader for a file, use
File file = new File ("...path...");
String encoding = "...."; // Encoding of your file
Reader reader = new BufferedReader (new InputStreamReader (
new FileInputStream (file), encoding));
... use reader ...
reader.close ();
You should really specify the encoding or else you will get strange results when you encounter umlauts, Unicode and the like.
Easiest option is to simply use the Apache Commons IO JAR and import the org.apache.commons.io.FileUtils class. There are many possibilities when using this class, but the most obvious would be as follows;
List<String> lines = FileUtils.readLines(new File("untitled.txt"));
It's that easy.
"Don't reinvent the wheel."
The best approach to read a file in Java is to open in, read line by line and process it and close the strea
// Open the file
FileInputStream fstream = new FileInputStream("textfile.txt");
BufferedReader br = new BufferedReader(new InputStreamReader(fstream));
String strLine;
//Read File Line By Line
while ((strLine = br.readLine()) != null) {
// Print the content on the console - do what you want to do
System.out.println (strLine);
}
//Close the input stream
fstream.close();
To learn more about how to read file in Java, check out the article.
Your question is not very clear, so I'll only answer for the "read" part :
List<String> lines = new ArrayList<String>();
BufferedReader br = new BufferedReader(new FileReader("fileName"));
String line = br.readLine();
while (line != null)
{
lines.add(line);
line = br.readLine();
}
Common used:
String line = null;
File file = new File( "readme.txt" );
FileReader fr = null;
try
{
fr = new FileReader( file );
}
catch (FileNotFoundException e)
{
System.out.println( "File doesn't exists" );
e.printStackTrace();
}
BufferedReader br = new BufferedReader( fr );
try
{
while( (line = br.readLine()) != null )
{
System.out.println( line );
}
#user248921 first of all, you can store anything in string array , so you can make string array and store a line in array and use value in code whenever you want. you can use the below code to store heterogeneous(containing string, int, boolean,etc) lines in array.
public class user {
public static void main(String x[]) throws IOException{
BufferedReader b=new BufferedReader(new FileReader("<path to file>"));
String[] user=new String[500];
String line="";
while ((line = b.readLine()) != null) {
user[i]=line;
System.out.println(user[1]);
i++;
}
}
}
This is a nice way to work with Streams and Collectors.
List<String> myList;
try(BufferedReader reader = new BufferedReader(new FileReader("yourpath"))){
myList = reader.lines() // This will return a Stream<String>
.collect(Collectors.toList());
}catch(Exception e){
e.printStackTrace();
}
When working with Streams you have also multiple methods to filter, manipulate or reduce your input.
For Java 11 you could use the next short approach:
Path path = Path.of("file.txt");
try (var reader = Files.newBufferedReader(path)) {
String line;
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
}
Or:
var path = Path.of("file.txt");
List<String> lines = Files.readAllLines(path);
lines.forEach(System.out::println);
Or:
Files.lines(Path.of("file.txt")).forEach(System.out::println);
How do you read and display data from .txt files?
BufferedReader in = new BufferedReader(new FileReader("<Filename>"));
Then, you can use in.readLine(); to read a single line at a time. To read until the end, write a while loop as such:
String line;
while((line = in.readLine()) != null)
{
System.out.println(line);
}
in.close();
If your file is strictly text, I prefer to use the java.util.Scanner class.
You can create a Scanner out of a file by:
Scanner fileIn = new Scanner(new File(thePathToYourFile));
Then, you can read text from the file using the methods:
fileIn.nextLine(); // Reads one line from the file
fileIn.next(); // Reads one word from the file
And, you can check if there is any more text left with:
fileIn.hasNext(); // Returns true if there is another word in the file
fileIn.hasNextLine(); // Returns true if there is another line to read from the file
Once you have read the text, and saved it into a String, you can print the string to the command line with:
System.out.print(aString);
System.out.println(aString);
The posted link contains the full specification for the Scanner class. It will be helpful to assist you with what ever else you may want to do.
In general:
Create a FileInputStream for the file.
Create an InputStreamReader wrapping the input stream, specifying the correct encoding
Optionally create a BufferedReader around the InputStreamReader, which makes it simpler to read a line at a time.
Read until there's no more data (e.g. readLine returns null)
Display data as you go or buffer it up for later.
If you need more help than that, please be more specific in your question.
I love this piece of code, use it to load a file into one String:
File file = new File("/my/location");
String contents = new Scanner(file).useDelimiter("\\Z").next();
Below is the code that you may try to read a file and display in java using scanner class. Code will read the file name from user and print the data(Notepad VIM files).
import java.io.*;
import java.util.Scanner;
import java.io.*;
public class TestRead
{
public static void main(String[] input)
{
String fname;
Scanner scan = new Scanner(System.in);
/* enter filename with extension to open and read its content */
System.out.print("Enter File Name to Open (with extension like file.txt) : ");
fname = scan.nextLine();
/* this will reference only one line at a time */
String line = null;
try
{
/* FileReader reads text files in the default encoding */
FileReader fileReader = new FileReader(fname);
/* always wrap the FileReader in BufferedReader */
BufferedReader bufferedReader = new BufferedReader(fileReader);
while((line = bufferedReader.readLine()) != null)
{
System.out.println(line);
}
/* always close the file after use */
bufferedReader.close();
}
catch(IOException ex)
{
System.out.println("Error reading file named '" + fname + "'");
}
}
}
If you want to take some shortcuts you can use Apache Commons IO:
import org.apache.commons.io.FileUtils;
String data = FileUtils.readFileToString(new File("..."), "UTF-8");
System.out.println(data);
:-)
public class PassdataintoFile {
public static void main(String[] args) throws IOException {
try {
PrintWriter pw = new PrintWriter("C:/new/hello.txt", "UTF-8");
PrintWriter pw1 = new PrintWriter("C:/new/hello.txt");
pw1.println("Hi chinni");
pw1.print("your succesfully entered text into file");
pw1.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
BufferedReader br = new BufferedReader(new FileReader("C:/new/hello.txt"));
String line;
while((line = br.readLine())!= null)
{
System.out.println(line);
}
br.close();
}
}
In Java 8, you can read a whole file, simply with:
public String read(String file) throws IOException {
return new String(Files.readAllBytes(Paths.get(file)));
}
or if its a Resource:
public String read(String file) throws IOException {
URL url = Resources.getResource(file);
return Resources.toString(url, Charsets.UTF_8);
}
You most likely will want to use the FileInputStream class:
int character;
StringBuffer buffer = new StringBuffer("");
FileInputStream inputStream = new FileInputStream(new File("/home/jessy/file.txt"));
while( (character = inputStream.read()) != -1)
buffer.append((char) character);
inputStream.close();
System.out.println(buffer);
You will also want to catch some of the exceptions thrown by the read() method and FileInputStream constructor, but those are implementation details specific to your project.