Develop Reference

How to pass the file path as an argument in RandomFileAccess Object in android?

There is a small problem in the following code that it is unable to find the text file src/main/res/raw/dictionary.txt:
RandomAccessFile ifl = new RandomAccessFile("android.resource://"
+ getPackageName() + "/" + R.raw.dict , "r");
Is there any other way by which the text file can successfully be found and opened? Is there a way if we keep these files in 'assets' folder and then access? Plz suggest.

you can better use InputStream to read text in raw folder file ,
public String readRawFile()
{
StringBuilder builder = new StringBuilder();
InputStream in = getResources().openRawResource(R.raw.yourfile);
try {
int count = 0;
byte[] bytes = new byte[32768];
while ( (count = in.read(bytes,0, 32768)) > 0) {
builder.append(new String(bytes, 0, count));
}
in.close();
} catch (IOException e) {
e.printStackTrace();
}
return builder.toString();
}

Getting Stream closed when reading/writing to file Java

I'm implementing a small tool in Java. I have a excel document and from every sheet I need to generate a .sql file. I've created an sql file model, which I have to read from for every excel sheet then replace a value and write it back to another .sql file. The problem is I use a for where I loop through my sheets and for every sheet I need to read that sql file, modify it and export it somewhere else. I get a "Stream closed" error, and I don't know how to close my buffer and/or my InputStream properly. Can you guys help me out with this ?
This is my code:
This gets everything from the file and converts it to a String
public String getString(InputStream is) throws IOException {
BufferedReader reader = null;
StringBuilder sb = new StringBuilder();
String line;
try {
reader = new BufferedReader(new InputStreamReader(is));
while ((line = reader.readLine()) != null) {
sb.append(line + System.lineSeparator());
}
} catch (IOException ex) {
ex.printStackTrace();
}
return sb.toString();
}
This is used to export the file
public void exportFile(String text, String path, String name, String extension) {
BufferedWriter output = null;
try {
File sqlFile = new File(path + name + extension);
output = new BufferedWriter(new FileWriter(sqlFile));
output.write(text);
} catch (IOException e) {
e.printStackTrace();
logger.severe("Unable to write to file!\n");
} finally {
if (output != null) {
try {
output.close();
} catch (IOException e) {
e.printStackTrace();
logger.severe("Unable to close buffer\n");
}
}
}
}
And this a the part of my run() method, which uses the code above:
ClassLoader loader = this.getClass().getClassLoader();
InputStream createTableInputStream = loader.getResourceAsStream("val_table_create.sql");
if (createTableInputStream == null) {
logger.severe("No tempalte found for creating table!\n");
return;
}
List<Sheet> bookSheets = getSheets(book);
for (Sheet sheet : bookSheets) {
setHeader(table, sheet);
String exportText = getString(createTableInputStream);
exportText = exportText.replaceAll(TABLE_NAME, tableName);
// exportText = exportText.replaceAll(VAL_DATA_TYPE, valDataType);
// exportText = exportText.replaceAll(MSG_TEXT_DATA_TYPE, messageDataType);
exportFile(exportText, absoluteWorkspacePath + File.separator + outputPath + File.separator, tableName, ".sql");
}
if (createTableInputStream != null) {
createTableInputStream.close();
}

The Problem is in this method:
public String getString(InputStream is) throws IOException {
You close the the reader and stream at the end. (When you close the reader the streams in it are automatic close.
Edit: You should close the reader. getString(InputStream is) throws IOException returns always the same String or? Read it before you go in the loop and reuse the String everytime.
String exportText = getString("val_table_create.sql");
for (Sheet sheet : bookSheets) {
setHeader(table, sheet);
String newExportText = exportText.replaceAll(TABLE_NAME, tableName);
messageDataType);
exportFile(newExportText, absoluteWorkspacePath + File.separator + outputPath + File.separator, tableName, ".sql");
}
Change your getString Method to this:
public String getString(String resourceName) throws IOException {
BufferedReader reader = null;
StringBuilder sb = new StringBuilder();
String line;
try {
InputStream createTableInputStream reader.getResourceAsStream(resourceName);
reader = new BufferedReader(new InputStreamReader(is));
while ((line = reader.readLine()) != null) {
sb.append(line + System.lineSeparator());
}
} catch (IOException ex) {
ex.printStackTrace();
}
return sb.toString();
}
and close there all the streams. Now you have one place where you load your file.

createTableInputStream will be closed for the first time you call getString method so for next sheet in loop you will get stream closed.
It's a better practice to close the stream in the method who created it. You should close the stream in run method instead.

Error in reading file java.io

So i'm trying to read the following string from the text file addToLibrary.txt
file:/Users/JEAcomputer/Music/iTunes/iTunes%20Media/Music/Flight%20Of%20The%20Conchords/Flight%20Of%20The%20Conchords/06%20Mutha'uckas.mp3
But when I do i get the following error:
java.io.FileNotFoundException: file:/Users/JEAcomputer/Music/iTunes/iTunes%20Media/Music/Flight%20Of%20The%20Conchords/Flight%20Of%20The%20Conchords/06%20Mutha'uckas.mp3 (No such file or directory)
Whats odd is that I got that string from a fileChooser using this method:
public static void addToLibrary(File f) {
String fileName = "addToLibrary.txt";
try {
FileWriter filewriter = new FileWriter(fileName, true);
BufferedWriter bufferedWriter = new BufferedWriter(filewriter);
bufferedWriter.newLine();
bufferedWriter.write(f.toURI().toString());
System.out.println("Your file has been written");
bufferedWriter.close();
} catch (IOException ex) {
System.out.println(
"Error writing to file '"
+ fileName + "'");
} finally {
}
}
An even stranger error is that my file reader can read things in another folder but not anything in iTunes Media.
I attempt to read all the files in the different folders with the following method:
public void getMusicDirectory() {
int index = 0;
try {
File[] contents = musicDir.listFiles();
//System.out.println(contents[3].toString());
for (int i = 0; i < contents.length; i++) {
//System.out.println("----------------------------------------"+contents.length);
String name = contents[i].getName();
//System.out.println(name);
if (name.indexOf(".mp3") == -1) {
continue;
}
FileInputStream file = new FileInputStream(contents[i]);
file.read();
System.out.println(contents[i].toURI().toString());
songsDir.add(new Song((new MediaPlayer(new Media(contents[i].toURI().toString()))), contents[i]));
file.close();
}
} catch (Exception e) {
System.out.println("Error -- " + e.toString());
}
try(BufferedReader br = new BufferedReader(new FileReader("addToLibrary.txt"))) {
//System.out.println("In check login try");
for (String line; (line = br.readLine()) != null; ) {
FileInputStream file = new FileInputStream(new File(line));
file.read();
songsDir.add(new Song(new MediaPlayer(new Media(line)), new File(line)));
file.close();
}
// line is not visible here.
} catch (Exception e) {
System.out.println("Error reading add to library-- " + e.toString());
}
}
So how can i make this work? why does the first part of the method work but not the second?

You are not having a problem reading the string
file:/Users/JEAcomputer/Music/iTunes/iTunes%20Media/Music/Flight%20Of%20The%20Conchords/Flight%20Of%20The%20Conchords/06%20Mutha'uckas.mp3
from a file. That part works fine. Your problem is after that, when you try to open the file with the path:
file:/Users/JEAcomputer/Music/iTunes/iTunes%20Media/Music/Flight%20Of%20The%20Conchords/Flight%20Of%20The%20Conchords/06%20Mutha'uckas.mp3
because that's not actually a path; it's a URI (although it can be converted to a path).
You could convert this to a path, in order to open it, but you have no reason to - your code doesn't actually read from the file (apart from the first byte, which it does nothing with) so there's no point in opening it. Delete the following lines:
FileInputStream file = new FileInputStream(contents[i]); // THIS ONE
file.read(); // THIS ONE
System.out.println(contents[i].toURI().toString());
songsDir.add(new Song((new MediaPlayer(new Media(contents[i].toURI().toString()))), contents[i]));
file.close(); // THIS ONE
and
FileInputStream file = new FileInputStream(new File(line)); // THIS ONE
file.read(); // THIS ONE
songsDir.add(new Song(new MediaPlayer(new Media(line)), new File(line)));
file.close(); // THIS ONE

file:/Users/JEAcomputer/Music/iTunes/iTunes%20Media/Music/Flight%20Of%20The%20Conchords/Flight%20Of%20The%20Conchords/06%20Mutha'uckas.mp3 is not a valid File reference, especially under Windows.
Since you've idendtified the String as a URI, you should treat it as such...
URI uri = URI.create("file:/Users/JEAcomputer/Music/iTunes/iTunes%20Media/Music/Flight%20Of%20The%20Conchords/Flight%20Of%20The%20Conchords/06%20Mutha'uckas.mp3");
Okay, but, there's no real way to read URI, but you can read a URL, so we need to convert the URI to URL, luckily, this is quite simple...
URL url = uri.toURL();
From there you can use URL#openStream to open an InputStream (which you can wrap in a InputStreamReader) and read the contents of the file, for example...
String imageFile = "file:/...";
URI uri = URI.create(imageFile);
try {
URL url = uri.toURL();
try (InputStream is = url.openStream()) {
byte[] bytes = new byte[1024 * 4];
int bytesRead = -1;
int totalBytesRead = 0;
while ((bytesRead = is.read(bytes)) != -1) {
// Somthing, something, something, bytes
totalBytesRead += bytesRead;
}
System.out.println("Read a total of " + totalBytesRead);
} catch (IOException ex) {
ex.printStackTrace();
}
} catch (MalformedURLException ex) {
ex.printStackTrace();
}
You could, however, save your self a lot of issues and stop using things like f.toURI().toString()); (File#toURI#toString) and simply use File#getPath instead...This would allow you to simply create a new File reference from the String...
Also, your resource management needs some work, basically, if you open it, you should close it. See The try-with-resources Statement for some more ideas

I am trying to modify some lines in text files and when I write that line back again to the file, I end up with a blank file

This code is reading a bunch of .java files and finding "public [classname]" or "private [classname]" and adding "System.out.println([classname])" to that line.
The problem is When I write that line back in I end up with a blank file
Can anyone see what I am doing wrong?
private static void work(ArrayList<File> fileList) {
for (int i = 0; i < fileList.size(); i++) {
replaceLines(fileList.get(i));
}
}
public static void replaceLines(File file) {
String path = file.getPath();
String fileNameLong = file.getName();
String fileName = null;
if (fileNameLong.contains(".java")) {
fileName = fileNameLong.substring(0, file.getName().indexOf("."));
}
if (fileName != null && fileName != "") {
System.out.println(fileName);
try {
//prepare reading
FileInputStream in = new FileInputStream(path);
BufferedReader br = new BufferedReader(
new InputStreamReader(in));
//prepare writing
FileWriter fw = new FileWriter(file);
PrintWriter out = new PrintWriter(fw);
String strLine;
while ((strLine = br.readLine()) != null) {
// Does it contain a public or private constructor?
boolean containsPrivateCon = strLine.contains("private "
+ fileName);
boolean containsPublicCon = strLine.contains("public "
+ fileName);
if (containsPrivateCon || containsPublicCon) {
int lastIndexOfBrack = strLine.lastIndexOf("{");
while (lastIndexOfBrack == -1) {
strLine = br.readLine();
lastIndexOfBrack = strLine.lastIndexOf("{");
}
if (lastIndexOfBrack != -1) {
String myAddition = "\n System.out.println(\""
+ fileName + ".java\"); \n";
String strLineModified = strLine.substring(0,
lastIndexOfBrack + 1)
+ myAddition
+ strLine.substring(lastIndexOfBrack + 1);
strLine = strLineModified;
}
}
out.write(strLine);
}
} catch (Exception e) {
System.out.println(e);
}
}
}

If you want to write to the same file you're reading from, you should either write to a copy of the file (different filename) and then rename the output file, or use RandomAccessFile interface to edit a file in-place.
Usually, the first solution will be much easier to implement than the second one; unless the files are huge (which is probably not the case with .java files), there is no real reason to use the second.

You forgot to flush and close the file. PrintWriter keeps a buffer and unless you explicitly flush() it, the data will (un)happily sit in the buffer and it will never be written to the output.
So you need to add this before the line catch (Exception e) {
out.flush();
out.close();
Note that this is only necessary for PrintWriter and PrintStream. All other output classes flush when you close them.

File handling in java

I have the below code.
The below source code is from the file x.java. The hi.html is present in the same directory as x.java.
I get a file not found exception even though the file is present. Am I missing something ?
public void sendStaticResource() throws IOException{
byte[] bytes = new byte[1024];
FileInputStream fis = null;
try{
File file = new File("hi.html");
boolean p = file.exists();
int i = fis.available();
fis = new FileInputStream(file);
int ch = fis.read(bytes, 0, 1024);
while(ch!=-1){
output.write(bytes, 0, ch);
ch = fis.read(bytes, 0, 1024);
}
}catch(Exception e){
String errorMessage = "file not found";
output.write(errorMessage.getBytes());
}finally {
if(fis != null){
fis.close();
}
}
}

The directory of the .java file is not necessarily the direction your code runs in! You can check the current working dir of your program by in example:
System.out.println( System.getProperty( "user.dir" ) );
You could use the System.getProperty( "user.dir" ) string to make your relative filename an absolute one! Just prefix it to your filename :)

Take a look at your "user.dir" property.
String curDir = System.getProperty("user.dir");
That's where the program will root its search for files that don't have a complete path.

Catch the FileNotFoundException before catching Exception so as to be sure that is the real Exception type.
Since you don't give an absolute location for a file it searches from your working directory. You can store the absolute path in a property file and use that instead or use System.getProperty("user.dir") to return the directory that you are running the Java app from.
Code to get Key-Value from Property files
private void getPropertyFileValues() {
String currentPath = System.getProperty("user.dir") + System.getProperty("file.separator") + "Loader.properties";
FileInputStream fis = null;
try {
fis = new FileInputStream(currentPath);
} catch (FileNotFoundException ex) {
ex.printStackTrace();
}
Properties props = new Properties();
try {
props.load(fis);
} catch (IOException ex) {
ex.printStackTrace();
}
String filePath= props.getProperty("FILE_PATH");
try {
fis.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}

I guess you get a NullPointerException:
FileInputStream fis = null;
then the call:
int i = fis.available();
will result in an NullPointerException as the first non-null assignment to fis is later:
fis = new FileInputStream(file);

File Handling in Java:
Use File class for Representing and manipulating file or folder/directory.
you can use constructor :
ex. File file = new File("path/file_name.txt");
or
File file = new File("Path","file_name");
File representation example:
import java.io.File;
import java.util.Date;
import java.io.*;
import java.util.*;
public class FileRepresentation {
public static void main(String[] args) {
File f =new File("path/file_name.txt");
if(f.exists()){
System.out.println("Name " + f.getName());
System.out.println("Absolute path: " +f.getAbsolutePath());
System.out.println("Is writable " +f.canWrite());
System.out.println("Is readable " + f.canRead());
System.out.println("Is File " + f.isFile());
System.out.println("Is Directory " + f.isDirectory());
System.out.println("Last Modified at " + new Date(f.lastModified()));
System.out.println("Length " + f.length() +"bytes long.");
}//if
}//main
}//class

Write data character by character, into Text file by Java:
use FileWriter Class-
import java.io.FileWriter;
import java.io.PrintWriter;
import java.io.Writer;
public class WriteFile {
public static void main(String[] args) throws Exception{
//File writer takes chars and convert into bytes and write to a file
FileWriter writer = new FileWriter("path/file_name.txt");
//if file not exits then created it, else override data
writer.write('A');
writer.write('E');
writer.write('I');
writer.write('O');
writer.write('U');
writer.close();
System.out.println("Successfully Written");
}
}