Develop Reference

Java too many open files exception

I have a problem on my code; basically I have an array containing some key:
String[] ComputerScience = { "A", "B", "C", "D" };
And so on, containing 40 entries.
My code reads 900 pdf from 40 folder corresponding to each element of ComputerScience, manipulates the extracted text and stores the output in a file named A.txt , B.txt, ecc ...
Each folder "A", "B", ecc contains 900 pdf.
After a lot of documents, an exception "Too many open files" is thrown.
I'm supposing that I am correctly closing files handler.
static boolean writeOccurencesFile(String WORDLIST,String categoria, TreeMap<String,Integer> map) {
File dizionario = new File(WORDLIST);
FileReader fileReader = null;
FileWriter fileWriter = null;
try {
File cat_out = new File("files/" + categoria + ".txt");
fileWriter = new FileWriter(cat_out, true);
} catch (IOException e) {
e.printStackTrace();
}
try {
fileReader = new FileReader(dizionario);
} catch (FileNotFoundException e) { }
try {
BufferedReader bufferedReader = new BufferedReader(fileReader);
if (dizionario.exists()) {
StringBuffer stringBuffer = new StringBuffer();
String parola;
StringBuffer line = new StringBuffer();
int contatore_index_parola = 1;
while ((parola = bufferedReader.readLine()) != null) {
if (map.containsKey(parola) && !parola.isEmpty()) {
line.append(contatore_index_parola + ":" + map.get(parola).intValue() + " ");
map.remove(parola);
}
contatore_index_parola++;
}
if (! line.toString().isEmpty()) {
fileWriter.append(getCategoryID(categoria) + " " + line + "\n"); // print riga completa documento N x1:y x2:a ...
}
} else { System.err.println("Dictionary file not found."); }
bufferedReader.close();
fileReader.close();
fileWriter.close();
} catch (IOException e) { return false;}
catch (NullPointerException ex ) { return false;}
finally {
try {
fileReader.close();
fileWriter.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return true;
}
But the error still comes. ( it is thrown at:)
try {
File cat_out = new File("files/" + categoria + ".txt");
fileWriter = new FileWriter(cat_out, true);
} catch (IOException e) {
e.printStackTrace();
}
Thank you.
EDIT: SOLVED
I found the solution, there was, in the main function in which writeOccurencesFile is called, another function that create a RandomAccessFile and doesn't close it.
The debugger sais that Exception has thrown in writeOccurencesFile but using Java Leak Detector i found out that the pdf were already opened and not close after parsing to pure text.
Thank you!

Try using this utility specifically designed for the purpose.
This Java agent is a utility that keeps track of where/when/who opened files in your JVM. You can have the agent trace these operations to find out about the access pattern or handle leaks, and dump the list of currently open files and where/when/who opened them.
When the exception occurs, this agent will dump the list, allowing you to find out where a large number of file descriptors are in use.

i have tried using try-with resources; but the problem remains.
Also running in system macos built-in console print out a FileNotFound exception at the line of FileWriter fileWriter = ...
static boolean writeOccurencesFile(String WORDLIST,String categoria, TreeMap<String,Integer> map) {
File dizionario = new File(WORDLIST);
try (FileWriter fileWriter = new FileWriter( "files/" + categoria + ".txt" , true)) {
try (FileReader fileReader = new FileReader(dizionario)) {
try (BufferedReader bufferedReader = new BufferedReader(fileReader)) {
if (dizionario.exists()) {
StringBuffer stringBuffer = new StringBuffer();
String parola;
StringBuffer line = new StringBuffer();
int contatore_index_parola = 1;
while ((parola = bufferedReader.readLine()) != null) {
if (map.containsKey(parola) && !parola.isEmpty()) {
line.append(contatore_index_parola + ":" + map.get(parola).intValue() + " ");
map.remove(parola);
}
contatore_index_parola++;
}
if (!line.toString().isEmpty()) {
fileWriter.append(getCategoryID(categoria) + " " + line + "\n"); // print riga completa documento N x1:y x2:a ...
}
} else {
System.err.println("Dictionary file not found.");
}
}
}
} catch (IOException e) {
e.printStackTrace();
}
return true;
}
This is the code that i am using now, although the bad managing of Exception, why the files seem to be not closed?
Now i am making a test with File Leak Detector

Maybe your code raises another exception that you are not handling. Try add catch (Exception e) before finally block
You also can move BufferedReader declaration out the try and close it in finally

Setting value of an attribute when uploading file to database

I have a .csv file "Salesman" that will be uploaded to the sqlite database. This file contains details about a Salesman.
A sample row for Salesman:
-----------
|code|name|
-----------
|0001|Jon|
-----------
|0002|Stu|
DDL for Salesman:
CREATE TABLE salesman (
code INTEGER NOT NULL,
name TEXT NOT NULL,
isSelected INTEGER NOT NULL,
PRIMARY KEY (
code
)
);
The attribute isSelected acts as a tag stating that the Salesman has been selected, thus cannot be chosen again.
This is my code for getting Salesman details from .CSV file:
public static ArrayList<Salesman> getSalesmanFromFile(String filePath){
ArrayList<Salesman> salesmanList= new ArrayList<Salesman>();
try {
BufferedReader br = new BufferedReader(new FileReader(filePath));
String line = null;
String[] strSalesman = null;
try {
while ((line=br.readLine()) != null){
strSalesman = line.split(",");
salesmanList.add(new Salesman(Integer.parseInt(strSalesman[0]), strSalesman[1]));
}
} catch (IOException ex) {
ex.printStackTrace();
} finally {
try {
br.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}
} catch (FileNotFoundException ex) {
ex.printStackTrace();
String status = "Error"; //- Please review file selected. Make sure that format is followed.";
}
return salesmanList;
}
My question is, how can I set the third attribute isSelected in the method to 0 (not selected)? Since .csv file doesn't contain the tagging attribute, I'm thinking of placing it in the method above (which will be used at the start of the whole program).
I'm thinking of creating a variable within the method int isSelected = 0 but I don't know how to incorporate it with the BufferedReader. Something like:
BufferedReader br = new BufferedReader(new FileReader(filePath));
String line = null;
String[] strSalesman = null;
//int isSelected = 0;
try {
while ((line=br.readLine()) != null){
strSalesman = line.split(",");
salesmanList.add(new Salesman(Integer.parseInt(strSalesman[0]), strSalesman[1], isSelected?));
}
} catch (IOException ex) {
ex.printStackTrace();
}
Any help would be appreciated!

How do I read a CSV file into my local Oracle Database table?

My goal is to read from a CSV file, loading it into a sample database table (Oracle) that I have .
So far , I have the following Java code :
public class ParsingCSV {
public static void main(String[] args) {
ParsingCSV obj = new ParsingCSV();
obj.run();
}
#SuppressWarnings("oracle.jdeveloper.java.nested-assignment")
public void run() {
String csvFile = "C:\\Users\\IBM_ADMIN\\Desktop\\Work\\ConnectOne_Bancorp\\Database_Work\\Book1.csv";
BufferedReader br = null;
String line = "";
String cvsSplitBy = ",";
try {
br = new BufferedReader(new FileReader(csvFile));
while ((line = br.readLine()) != null) {
// use comma as separator
String[] country = line.split(cvsSplitBy);
System.out.println("Country [code= " + country[4]
+ " , name=" + country[5] + "]");
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
/* boilerplate */
any tips/pointers appreciated , thanks !

The tips could be:
Download the Oracle Database driver Oracle driver
Set the .jar to your classpath. [java setting class path]
Register the driver and connect to the database [java connect to oracle]
Execute sql "CREATE TABLE...." [sql create table example]
For every line that you read do sql = "INSERT INTO..." [sql insert into example]
For every step if you need more example and advice, I suggest google use the [] tags to search

Append a string in front of line in java?

I am creating a pattern lock based project in android.
I have a file called category.txt
The content of the file is as below
Sports:Race:Arcade:
No what i want is that whenever the user draw a pattern for a specific games category the pattern should get append in front of that category.
eg :
Sports:Race:"string/pattern string to be appended here for race"Arcade:
i have used following code but it is not working.
private void writefile(String getpattern,String category)
{
String str1;
try {
file = new RandomAccessFile(filewrite, "rw");
while((str1 = file.readLine()) != null)
{
String line[] = str1.split(":");
if(line[0].toLowerCase().equals(category.toLowerCase()))
{
String colon=":";
file.write(category.getBytes());
file.write(colon.getBytes());
file.write(getpattern.getBytes());
file.close();
Toast.makeText(getActivity(),"In Writefile",Toast.LENGTH_LONG).show();
}
}
}
catch (FileNotFoundException e)
{
e.printStackTrace();
}
catch(IOException io)
{
io.printStackTrace();
}
}
please help !

Using RandomAccessFile you have to calculate the position. I think it's much easier to just replace the file content with a little help from apache-commons-io FileUtils. This might be not the best idea if you have a very large file but it's quite simple.
String givenCategory = "Sports";
String pattern = "stringToAppend";
final String colon = ":";
try {
List<String> lines = FileUtils.readLines(new File("someFile.txt"));
String modifiedLine = null;
int index = 0;
for (String line : lines) {
String[] categoryFromLine = line.split(colon);
if (givenCategory.equalsIgnoreCase(categoryFromLine[0])) {
modifiedLine = new StringBuilder().append(pattern).append(colon).append(givenCategory).append(colon).toString();
break;
}
index++;
}
if (modifiedLine != null) {
lines.set(index, modifiedLine);
FileUtils.writeLines(new File("someFile.txt"), lines);
}
} catch (IOException e1) {
// do something
}

Using FileWriter to convert Google Analytics data into CSV file using JAVA

Hi all after getting some advice, I am attempting to use the filewriter method in order to export my google analytics queries that i got to a CSV file format here is what i have so far
private static void printGaData(GaData results) {
try {
PrintWriter pw = new PrintWriter(BufferedWriter(new FileWriter("data.csv")));
}
catch(Exception e) {
e.printStackTrace();
}
System.out.println(
"printing results for profile: " + results.getProfileInfo().getProfileName());
if (results.getRows() == null || results.getRows().isEmpty()) {
System.out.println("No results Found.");
} else {
// Print column headers.
for (ColumnHeaders header : results.getColumnHeaders()) {
System.out.printf(header.getName() + ", ");
}
System.out.println();
// Print actual data.
for (List<String> row : results.getRows()) {
for (String column : row) {
pw.printf(row + ", ");
}
pw.println();
}
pw.println();
}
}
}
doesnt output any data and keeps saying that the pw is non extent and stuff like that

Your PrintWriter is inside the try catch block. If you define it outside like
PrintWriter pw = null;
try {
pw = new PrintWriter(BufferedWriter(new FileWriter("data.csv")));
} catch (Exception e) {
// handle exception
}
then it will be available to the rest of your code.