Read textfile line by line - java

I tried it this way but it doesn't find the textfile.
try {
FileInputStream fstream = new FileInputStream("textfile.txt");
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());
}
All files are in the same package.

Your text file is inside a the package "trainer" which is inside "src" so when you request it, you must use "src/trainer/textfile.txt". The preceding / denotes the root of the application and is optional if you're not exporting to runnable jars for example.
FileInputStream fstream = new FileInputStream("src/trainer/textfile.txt");

Related

How to handle FileNotFoundException using try and catch block in Java?

I have written a program in which I am reading a file through the BufferedReader. which file I am reading it may be in .txt format or .csv format.
I want in if file is not available with .txt extension BufferedReader read it with
.csv extension.
I have created a String "FileName" and storing file path on it. and in path variable i have stored file location.
path = "C:\Users\Desktop\folder(1)\"
and I am trying try catch block as follow.
try
{
FileName = path+"abc.txt";
}
catch(Exception e)
{
FileName = path+"abc.csv";
}
BufferedReader BR = new BufferedReader(new FileReader(FileName));
But I am getting java.io.FileNotFoundException.
The exception is thrown in the line BufferedReader SoftwareBundle = new BufferedReader(new FileReader(FileName));
So you need the try/catch-block arround this line:
try
{
FileName = path+"abc.txt";
BufferedReader SoftwareBundle = new BufferedReader(new FileReader(FileName));
}
catch(Exception e)
{
FileName = path+"abc.csv";
BufferedReader SoftwareBundle = new BufferedReader(new FileReader(FileName));
}
This is the ideal structure for the code:
String filename = null;
try (BufferedReader bundle = null) {
try {
filename = path + "abc.txt";
bundle = new BufferedReader(new FileReader(filename));
} catch(FileNotFoundException e) {
filename = path + "abc.csv";
bundle = new BufferedReader(new FileReader(FileName));
}
// use 'bundle' here
} catch(FileNotFoundException e) {
// log that >>neither<< file could be opened.
}
Notes:
Don't catch Exception. If you do that, you will catch all sorts of unexpected stuff, in addition to the exceptions that you are anticipating.
Use a "try with resource" to ensure that that the reader that was opened is always closed.
You need to get the scoping right ... unless you are prepared to duplicate the code that uses the reader.
Even with the "try again" logic, you still need to deal with the case where all of the filenames that you try fail. AND you need to make sure that the "all fail" case doesn't attempt to use the reader.

Android/java Cant read from .txt file in local storage

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);
}

Importing a text file in Android SDK

I've been trying to read a file for the last few days and have tried following other answers but have not succeeded. This is the code I currently have to import the text file:
public ArrayList<String> crteDict() {
try {
BufferedReader br = new BufferedReader
(new FileReader("/program/res/raw/levels.txt"));
String line;
while ((line = br.readLine()) != null) {
String[] linewrds = line.split(" ");
words.add(linewrds[0].toLowerCase());
// process the line.
}
br.close();
}
catch (FileNotFoundException fe){
fe.printStackTrace();
It is meant to read the text file and just create a long Array of words. It keeps ending up in the FileNotFoundException.
Please let me know any answers.
Thanks!
IF your file is stored in the res/raw folder of the android project, you can read it as follows, this code must be inside an Activity class, as this.getResources() refers to Context.getResources():
// The InputStream opens the resourceId and sends it to the buffer
InputStream is = this.getResources().openRawResource(R.raw.levels);
BufferedReader br = new BufferedReader(new InputStreamReader(is));
String readLine = null;
try {
// While the BufferedReader readLine is not null
while ((readLine = br.readLine()) != null) {
Log.d("TEXT", readLine);
}
// Close the InputStream and BufferedReader
is.close();
br.close();
} catch (IOException e) {
e.printStackTrace();
}

Reading a variable number of lines from a file

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

Writing the contents to a file from input stream

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");
}

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