I have a text file and a class (Reader) that reads the text file and stores each line in a String [].
String name;
String [] lines;
Reader(String name){
this.name = name;
}
public String toString(){
return this.name;
}
public readFile(String filename){
String line = "";
int i = 0;
try{
BufferedReader reader = new BufferedReader(new FileReader(filename));
while(line = reader.readLine()) != null){
lines[i] = line;
i++;
}// while
reader.close();
}
catch(etc...){}
}
I wish to print each array element in table on my jsp page.
Reader r = new Reader("test");
out.print(r.toString());
works and prints 'test' but...
r.readFile("test.txt")
for (int i=0; i < r.lines.length; i++)
out.print(r.lines[i])
does not... However if I run this on the command line its prints the lines [ ] fine
How do I go about doing it in web context?
Try replacing the following:
BufferedReader reader = new BufferedReader(new FileReader(filename));
with
BufferedReader reader = new BufferedReader(new InputStreamReader(this.getClass().getResourceAsStream(filename)));
That should work since the input file is in the same package as Reader.
Update:
I think the problem lies in the TeamData.
readFile("skytest\\data.file")
That's not a valid path to the file. Neither in filesystem, nor in the classpath.
Since, the data.file is in the classpath, you can use getResourceAsStream to load it.
And, since skytest is the root directory (package), "/skytest/data.file" would also be valid here (the leading / means relative package root). Or, since the file lies in the same package as the TeamData, just the file name should be enough "data.file".
So, use of the following:
readFile("data.file")
And change the following:
BufferedReader reader = new BufferedReader(new FileReader(requiredFile));
to
BufferedReader reader = new BufferedReader(new InputStreamReader(this.getClass().getResourceAsStream(requiredFile)));
Also, the following is really a bad practice (that's called swallowing the exception):
catch (IOException ioe) {
//do something about the exception here
return false;
}
Try something like this:
BufferedReader reader = null;
try
{
reader = new BufferedReader(new FileReader(new File("path/to/filename.txt")));
String nextLine = reader.readLine();
while (nextLine != null)
{
System.out.println(nextLine); // do stuff with the line you read in.
nextLine = reader.readLine();
}
reader.close();
}
catch (FileNotFoundException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
Related
What i'm trying to do, is to replace a symbol in a file text which contains over 4000 lines but using the below code, after the program ends, it only remain 500 lines. Why is this file truncated? How to solve this?
This is my code:
ArrayList<String> arrayList = new ArrayList<>();
try (FileReader fileReader = new FileReader(file);
BufferedReader bufferedReader = new BufferedReader(fileReader)) {
String line;
while ((line = bufferedReader.readLine()) != null) {
line = line.replace("þ", "t");
arrayList.add(line);
try (BufferedWriter bw = new BufferedWriter(new FileWriter(file))) {
for (String string : arrayList) {
bw.write(string + "\n");
}
} catch (Exception e) {System.err.println(e);}
}
} catch (Exception e) {e.printStackTrace();}
Thanks in advance!
new BufferedWriter(new FileWriter(file)) clear file.
You should open it only once. Also you reading and writing to the same file. You should use different files.
Like this
try (FileReader fileReader = new FileReader(inputFile);
BufferedReader bufferedReader = new BufferedReader(fileReader);
BufferedWriter bw = new BufferedWriter(new FileWriter(outputFile))) {
String line;
while ((line = bufferedReader.readLine()) != null) {
line = line.replace("þ", "t");
bw.write(line + "\n");
}
} catch (Exception e) {
e.printStackTrace();
}
You are writing to the same file while you are reading it. This won't work. Once you start writing, the file becomes empty (plus whatever you've written), so subsequent reads will report end-of-file. Your ~500 lines will be buffered input from the first read.
One solution is to do all the reading first, before opening the file again for writing:
Array<String> arrayList = new ArrayList<>();
try (BufferedReader bufferedReader = new BufferedReader(new FileReader(file))) {
while ((String line = bufferedReader.readLine()) != null) {
line = line.replace("þ", "t");
arrayList.add(line);
}
} catch (Exception e) {
e.printStackTrace();
}
try (BufferedWriter bw = new BufferedWriter(new FileWriter(file))) {
for (String string : arrayList) {
bw.write(string + "\n");
}
} catch (Exception e) {
System.err.println(e);
}
Here, first the program slurps the file into a List<String>, fixing the lines as it goes. Then it writes all the lines back out to the file.
There are circumstances in which this model is appropriate. For example, you might be building a non-linear data structure from the file content. Or you might need to see the last line before you can modify earlier lines (and be unable to re-open the data source from the start).
However I'd suggest a method that's more thrifty with memory. You don't need to keep all those lines in memory. You can read one line, fix it up, then forget about it. But to do this, you'll need to write to a second file.
String filein = "inputfile";
String fileout = filein + ".tmp";
try(
BufferedReader reader = new BufferedReader(new FileReader(filein));
Writer writer = new BufferedWriter(FileWriter(fileout))
) {
while ((String line = bufferedReader.readLine()) != null) {
writer.write(line.replace("þ", "t");
}
}
Files.move(Paths.get(fileout)),
Paths.get(filein),
CopyOption.REPLACE_EXISTING);
I have left out the necessary exception catching -- add back in as required.
I'm new to coding in java. Can anyone help me with my codes? I'm currently making a program where you input a string in a jTextArea, and if the input word(s) matches the one in the text file then it will then do something.
For example: I input the word 'Hey' then it will print something like "Hello" when the input word matches from the text file.
I hope you understand what I mean.
Here's my code:
String line;
String yo;
yo = jTextArea2.getText();
try (
InputStream fis = new FileInputStream("readme.txt");
InputStreamReader isr = new InputStreamReader(fis, Charset.forName("UTF-8"));
BufferedReader br = new BufferedReader(isr);
)
{
while ((line = br.readLine()) != null) {
if (yo.equalsIgnoreCase(line)) {
System.out.print("Hello");
}
}
} catch (IOException ex) {
Logger.getLogger(ArfArf.class.getName()).log(Level.SEVERE, null, ex);
}
You can not use equals for line because a line contain many words. You have to modify it to search the index of the word in a line.
try (InputStream fis = new FileInputStream("readme.txt");
InputStreamReader isr = new InputStreamReader(fis, Charset.forName("UTF-8"));
BufferedReader br = new BufferedReader(isr);) {
while ((line = br.readLine()) != null) {
line = line.toLowerCase();
yo = yo.toLowerCase();
if (line.indexOf(yo) != -1) {
System.out.print("Hello");
}
line = br.readLine();
}
} catch (IOException ex) {
}
since you are new in java , I would suggest you to take some time to study java 8 which enable to write more clean codes. below is the solution write in java 8, hope can give a kind of help
String yo = jTextArea2.getText();
//read file into stream,
try (java.util.stream.Stream<String> stream = Files.lines(Paths.get("readme.txt"))) {
List<String> matchLines = stream.filter((line) -> line.indexOf(yo) > -1).collect(Collectors.toList()); // find all the lines contain the text
matchLines.forEach(System.out::println); // print out all the lines contain yo
} catch (IOException e) {
e.printStackTrace();
}
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class WordFinder {
public static void main(String[] args) throws FileNotFoundException {
String yo = "some word";
Scanner scanner = new Scanner(new File("input.txt")); // path to file
while (scanner.hasNextLine()) {
if (scanner.nextLine().contains(yo)) { // check if line has your finding word
System.out.println("Hello");
}
}
}
}
I'm trying to make a program that reads a file name through a text field and displays it in a text area. I will also need a clear button. This is what I have so far:
private void enterButtonActionPerformed(java.awt.event.ActionEvent evt) {
String fileName = jTextField1.getText();
try {
FileReader fr = new FileReader(fileName);
BufferedReader br = new BufferedReader(fr);
String s;
while ((s = br.readLine()) != null) {
jTextArea1.setText(s + "\n");
}
br.close();
} catch (IOException e) {
jTextArea1.setText("File not found!");
}
}
private void clearButtonActionPerformed(java.awt.event.ActionEvent evt) {
jTextField1.setText("");
jTextArea1.setText("");
}
For some reason, it is not reading my text file on my desktop, called "hi". How could I make my program work? What am I doing wrong?
setText does that, sets the text of the field
Now, JTextArea has a simple read method for reading content, for example
try (BufferedReader reader = new BufferedReader(new FileReader(new File("resources/New Text Document.txt")))) {
textArea.read(reader, "File");
} catch (IOException exp) {
exp.printStackTrace();
}
I'm not sure about your problem but this seems not right to me and I want to mention to you to fix it:
Actually what you do is putting the last line of text in your textArea1 and if your last line is "\n" or an empty line, then obviously you don't see anything on your screen.
It would be good to use StringBuffer to store your lines which are read from the file and display the whole text. The following code can help you:
StringBuffer buffer = new StringBuffer();
String s;
while ((s = br.readLine()) != null) {
buffer.append(s).append('\n');
}
jTextArea1.setText(buffer.toString());
your code is actually working and it is reading the file, but your code goes wrong inside the while loop when you are assigning the value you are not concating string inside the while loop i have made some changes to your code try this one.
String fileName = "src/hi.txt";
String content = "";
try {
FileReader fr = new FileReader(fileName);
BufferedReader br = new BufferedReader(fr);
String s;
while ((s = br.readLine()) != null) {
content+="\n"+s;
}
System.out.println(content);
br.close();
} catch (Exception e) {
System.out.println("file not found");
}
I'm performing certain commands through command prompt and storing the values in a text file.
wmic logicaldisk where drivetype=3 get deviceid > drive.txt
Now I want to read the string stored in the text file from my java file. When I try to do this:
try {
File file = new File("drive.txt");
FileReader reader = new FileReader(file);
BufferedReader in = new BufferedReader(reader);
int i=0;
while ((string[i] = in.readLine()) != null) {
System.out.println(string[i]);
++i;
}
in.close();
} catch (IOException e) {
e.printStackTrace();
}
I get the output as follows:
ÿþD[]E[]V[]I[]C[]E[]
how to avoid this?
while ((string[i] = in.readLine()) != null) {
System.out.println(string[2]);
}
over there you are missing the i++;
However I would advise you to use this structure: Use a ArrayList instead of an array, since this allows you to have a self-resizing structure, also instead in the while use the method ready(); from the BufferedRead in order to check the end from the document, at the end the for it's just to display the elements in String ArrayList.
ArrayList<String> string = new ArrayList<String>();
try {
File file = new File("drive.txt");
BufferedReader entrada;
entrada = new BufferedReader(new FileReader(file));
entrada.readLine();
while (entrada.ready()) {
string.add(entrada.readLine());
}
entrada.close();
} catch (IOException e) {
e.printStackTrace();
}
for (String elements : string) {
System.out.println(elements);
}
Why do you need a string array here? The size of the array may be wrong? Simply use a string instead of array. I tried this and works fine for me:
try {
String string;
File file = new File("drive.txt");
FileReader reader = new FileReader(file);
BufferedReader in = new BufferedReader(reader);
int i = 0;
while ((string = in.readLine()) != null) {
System.out.println(string);
++i;
}
in.close();
} catch (IOException e) {
e.printStackTrace();
}
If you are using eclipse IDE, change the encoding type. Go to Edit->Set Encoding-> Others->UTF-8.
I have few text files. Each text file contains some path and/or the reference of some other file.
File1
#file#>D:/FilePath/File2.txt
Mod1>/home/admin1/mod1
Mod2>/home/admin1/mod2
File2
Mod3>/home/admin1/mod3
Mod4>/home/admin1/mod4
All I want is, copy all the paths Mod1, Mod2, Mod3, Mod4 in another text file by supplying only File1.txt as input to my java program.
What I have done till now?
public void readTextFile(String fileName){
try {
br = new BufferedReader(new FileReader(new File(fileName)));
String line = br.readLine();
while(line!=null){
if(line.startsWith("#file#>")){
String string[] = line.split(">");
readTextFile(string[1]);
}
else if(line.contains(">")){
String string[] = line.split(">");
svnLinks.put(string[0], string[1]);
}
line=br.readLine();
}
} catch (Exception e) {
e.printStackTrace();
}
}
Currently my code reads the contents of File2.txt only, control does not come back to File1.txt.
Please ask if more inputs are required.
First of all you are jumping to another file without closing the current reader and when you come back you lose the cursor. Read one file first and then write all its contents that match to another file. Close the current reader (Don't close the writer) and then open the next file to read and so on.
Seems pretty simple. You need to write your file once your svnLinks Map is populated, assuming your present code works (haven't seen anything too weird in it).
So, once the Map is populated, you could use something along the lines of:
File newFile = new File("myPath/myNewFile.txt");
// TODO check file can be written
// TODO check file exists or create
FileOutputStream fos = null;
OutputStreamWriter osw = null;
BufferedWriter bw = null;
try {
fos = new FileOutputStream(newFile);
osw = new OutputStreamWriter(fos);
bw = new BufferedWriter(osw);
for (String key: svnLinks.keySet()) {
bw.write(key.concat(" my separator ").concat(svnLinks.get(key)).concat("myNewLine"));
}
}
catch (Throwable t) {
// TODO handle more gracefully
t.printStackTrace();
if (bw != null) {
try {
bw.close();
}
catch (Throwable t) {
t.printStackTrace();
}
}
Here is an non-recursive implementation of your method :
public static void readTextFile(String fileName) throws IOException {
LinkedList<String> list = new LinkedList<String>();
list.add(fileName);
while (!list.isEmpty()) {
BufferedReader br = null;
try {
br = new BufferedReader(new FileReader(new File(list.pop())));
String line;
while ((line = br.readLine()) != null) {
if (line.startsWith("#file#>")) {
String string[] = line.split(">");
list.add(string[1]);
} else if (line.contains(">")) {
String string[] = line.split(">");
svnLinks.put(string[0], string[1]);
}
}
} catch (Exception e) {
e.printStackTrace();
} finally {
br.close();
}
}
}
Just used a LinkedList to maintain the order. I suggest you to add some counter if you to limit the reading of files to a certain number(depth). eg:
while (!list.isEmpty() && readCount < 10 )
This will eliminate the chance of running the code to infinity(in case of circular reference).