I'm trying to write in a file whatever the user has written.
The file creates and all but the program fails to write whatever the user wrote from the program, to the file (The program is like notepad). It wont enter the while loop because the String line is null even if I write something in my program.
It seems it's returning null when I print the "line" String after using br.readLine().
while ((line = br.readLine()) != null) {
bw.write(line);
textArea.append("it worked");
}
Full code:
try {
path = fileChooser.getSelectedFile().getAbsolutePath().replace('\\', '/')
+ "/";
File file = new File(path + File.separator +
JOptionPane.showInputDialog(null, "File name", "File") + ".txt");
file.createNewFile();
FileWriter fw = new FileWriter(file);
BufferedWriter bw = new BufferedWriter(fw);
BufferedReader br = new BufferedReader(new FileReader(file));
String line;
while ((line = br.readLine()) != null) {
bw.write(line);
textArea.append("it worked");
}
bw.flush();
bw.close();
textArea.append(path);
} catch(IOException e1) {
e1.printStackTrace();
}
file.createNewFile();
. . .
BufferedReader br = new BufferedReader(new FileReader(file));
The reader works from an empty file that just has been created. Of course br.readLine() will return null immediately since the file is empty.
Instead of the while loop, I would simply write:
bw.write(textArea.getText());
Related
So i have a .txt file in local storage its a simple text file. The text is basically just a series of lines.
I am using the code below to attempt to read the text file (i verify the file exists before calling this method).
public static String GetLocalMasterFileStream(String Operation) throws Exception {
//Get the text file
File file = new File("sdcard/CM3/advices/advice_master.txt");
if (file.canRead() == true) {System.out.println("-----Determined that file is readable");}
//Read text from file
StringBuilder text = new StringBuilder();
BufferedReader br = new BufferedReader(new FileReader(file));
String line;
while ((line = br.readLine()) != null) {
text.append(line);
System.out.println("-----" + line); //for producing test output
text.append('\n');
}
br.close();
System.out.print(text.toString());
return text.toString();
}
The code produces in the log
----Determined that file is readable
But that is the ONLY output the file data is not written to the log
Also i have tried inserting before the while loop the following to attempt to just read the first line
line = br.readLine();
System.out.println("-----" + line);
That produces the following output:
-----null
Check this out getExternalStorage
File path = Environment.getExternalStorageDirectory();
File file = new File(path, "textfile.txt");
//text file is copied in sdcard for example
Try to add a lead slash in file path /sdcard/CM3/advices/advice_master.txt
File file = new File("/sdcard/CM3/advices/advice_master.txt");
Try this. Just pass the txt file name as a parameter...
public void readFromFile(String fileName){
/*
InputStream ips;
ips = getClass().getResourceAsStream(fileName);
//reading
try{
InputStreamReader ipsr = new InputStreamReader(ips);
BufferedReader br = new BufferedReader(ipsr);
String line;
while ((line = br.readLine())!=null){
//reading goes here ;)
}
br.close();
}
catch (Exception e){
System.out.println(e.toString());
}
*/
// or try this
File sdcard = Environment.getExternalStorageDirectory();
//Get the text file
File file = new File(sdcard,"file.txt");
//Read text from file
StringBuilder text = new StringBuilder();
try {
BufferedReader br = new BufferedReader(new FileReader(file));
String line;
while ((line = br.readLine()) != null) {
text.append(line);
text.append('\n');
}
br.close();
}
catch (IOException e) {
//You'll need to add proper error handling here
}
}
Let me refine my answer. You can try another way to read all lines from advice_master.txt and see what happens. It makes sure that all file contents can be read.
Charset charset = Charset.forName("ISO-8859-1");
try {
List<String> lines = Files.readAllLines(Paths.get(YOUR_PATH), charset);
for (String line : lines) {
System.out.println(line);
}
} catch (IOException e) {
System.out.println(e);
}
I have a problem with writing data to my .txt file. It doesn't write all the data to my .txt file. I have tried it to put everything in a array, but also that doesn't works.
My code:
BufferedWriter writer = null;
try {
String line;
Process p = Runtime.getRuntime().exec("ps -A -o pid");
BufferedReader input =
new BufferedReader(new InputStreamReader(p.getInputStream()));
while ((line = input.readLine()) != null) {
writer = new BufferedWriter(new FileWriter(" the path .."));
writer.write(line);
System.out.println(line);
}
writer.close();
input.close();
} catch (Exception err) {
err.printStackTrace();
System.out.println("Sorry!");
}
It writes only the last line of the console.
By re-creating the object without closing it during every iteration of the loop, you are discarding what you have written so far (You have to use writer.close() to save what you have written using the object).
You will need to declare writer before the loop, so change it to the following
BufferedWriter writer = null;
try {
String line;
Process p = Runtime.getRuntime().exec("ps -A -o pid");
BufferedReader input =
new BufferedReader(new InputStreamReader(p.getInputStream()));
writer = new BufferedWriter(new FileWriter(" the path .."));
while ((line = input.readLine()) != null) {
writer.write(line);
System.out.println(line);
}
writer.close();
input.close();
} catch (Exception err) {
err.printStackTrace();
System.out.println("Sorry!");
}
Can I just ask, why were you re-declaring the writer object every iteration?
I want add few strings to a text file in a particular location.
I have used BufferedReader to read the text file. Then I added the string at the particular position and wrote the modified text to a new temp file using BufferedWriter.
Then I deleted the old file and renamed the temp file to old file name.
This works sometimes and does not work sometimes. The delete() function sometimes does not delete the file. I have closed all the BufferedWriter's, but the problem still occurs sometimes.
Code:
public boolean cart(String uname, String item) throws IOException {
File file = new File("C:\\$$$$.tmp");
if (!file.exists()) {
file.createNewFile();
}
FileWriter fw = new FileWriter(file.getAbsoluteFile(), true);
BufferedWriter bw = new BufferedWriter(fw);
File fileop = new File("C:\\value.text");
FileReader fr = new FileReader(fileop.getAbsoluteFile());
BufferedReader br = new BufferedReader(fr);
String line;
while((line = br.readLine()) != null) {
String val[] = line.split(",");
if (val[0].equals(uname)) {
String linenew = line + item + "&";
bw.append(linenew);
bw.newLine();
bw.flush();
} else {
bw.append(line);
bw.newLine();
bw.flush();
}
}
br.close();
bw.close();
fileop.delete();
file.renameTo(fileop);
return true;
}
I found the answer by myself after spending one full day of searching..
Answer is:
It is enough to close the bufferedReader but also the fileReader..
fr.close(); should be inserted after br.close();
I am trying to read a variable number of lines from a file, hopefully using InputStream object. What I'm trying to do (in a very general sense) is as follows:
Pass in long maxLines to function
Open InputStream and OutputStream for reading/writing
WHILE (not at the end of read file AND linesWritten < maxLines)
write to file
I know InputStream goes on bytes, not lines, so I'm not sure if that's a good API to use for this. If anyone has any reccomendations on what to look at in terms of a solution (other API's, different algorithm) that's be very helpful.
You can have something like this
BufferedReader br = new BufferedReader(new FileReader("FILE_LOCATION"));
while (br.readLine() != null && linesWritten < maxLines) {
//Your logic goes here
}
Have a look at these:
Buffered Reader and
Buffered Writer
//Read file into String allText
InputSream fis = new FileInputStream("filein.txt");
BufferedReader br = new BufferedReader(new InputStreamReader(fis));
String line, allText = "";
try {
while ((line = br.readLine()) != null) {
allText += (line + System.getProperty("line.separator")); //Track where new lines should be for output
}
} catch(IOException e) {} //Catch any errors
br.close(); //Close reader
//Write allText to new file
BufferedWriter bw = new BufferedWriter(new FileWriter("fileout.txt"));
try {
bw.write(allText);
} catch(IOException e) {} //Catch any errors
bw.close(); //Close writer
I want to write the inputstream into a file in java. How to write the contents into a text file in java?
try {
BufferedReader in = new BufferedReader(new
InputStreamReader(client.getInputStream()));
//I want to write the content to a file line by line here
while (!in.ready()) {}
System.out.print("'\n");
in.close();
}
FileWriter fstream = new FileWriter("fileName");
BufferedWriter fbw = new BufferedWriter(fstream);
while ((line = in.readLine()) != null) {
fbw.write(line + "\n");
}