Develop Reference

File.delete() isn't deleting the .Json file in Java

I am trying to delete a json file I just created, The file is in the same directory as the workplace so I didn't include it when creating the new File object.
I also closed the output stream before trying to delete the file by using .close() method.
import java.io.File;
public static void processFilesForValidation(String name, Scanner obj, PrintWriter logFile) {
int count = 0;
PrintWriter outputStream = null;
String[] line = obj.nextLine().split(",", -1);
if (count == 0) {
for (int i = 0; i < line.length; i++) {
try {
if (line[i].equals(" ")) {
throw new CSVFileInvalidException();
} else {
try {
outputStream = new PrintWriter((new FileOutputStream(name + ".json", true)));
} catch (FileNotFoundException e) {
System.out.println("Could not create json file " + name
+ ". Program will terminate after deleting any corrupted files and closing any opened files.");
obj.close();
outputStream.close();
String fname = name + ".json";
File file = new File(fname);
file.delete();
System.exit(0);
}
}
} catch (CSVFileInvalidException eCsvFileInvalidException) {
System.out.println(
"File " + name + ".CSV is invlaid: field is missing. \nFile is not converted to JSON.");
int detected = line.length - 1;
logFile.println("\nFile " + name + ".CSV is invalid. \nMissing field:" + detected
+ " detected, 1 missing");
for (int j = 0; j < line.length; j++) {
if (line[j].equals(" ")) {
logFile.print(line[j] + "***, ");
} else {
logFile.print(line[j] + ", ");
}
}
logFile.close();
outputStream.close();
String fname= name+".JSON";
File file = new File(fname);
file.delete();
break;
}
}
}
}
The code is a little long but this is the method, I hope you can help me.

You open a new outputStream every time around the loop. As far as I can tell, you only close it on a couple of errors. So, on loop #2, the first outputStream is left dangling and not closed.

CSV writing data beside each other

I am writing to CSV file the BLE scanned results. What I am doing currently is writing all the data one below another.
The data consists of device name, rssi and mac address. For example, the CSV file looks like this -
DeviceA -85 DS:DA:AB:2B:B4:AE
DeviceB -100 2C:18:0B:2B:96:9E
DeviceA -85 DS:DA:AB:2B:B4:AE
My requireemnt is to write like this -
DeviceA -85 DS:DA:AB:2B:B4:AE DeviceB -100 2C:18:0B:2B:96:9E
DeviceA -85 DS:DA:AB:2B:B4:AE
After the last column of device A, I need to start with new column of device B instead of writing below device A.
Also for Device C, I want to write it beside Device C...And so on. Here is my code for writing to CSV.
public final String DATA_SEPARATOR = ",";
public final String LINE_SEPARATOR = System
.getProperty("line.separator");
try {
fileName = "test.csv";
path = Environment.getExternalStorageDirectory()
+ File.separator + "Documents";
path += File.separatorChar + "SampleApp";
File file = new File(path, fileName);
new File(path).mkdirs();
file.createNewFile();
fileStream = new OutputStreamWriter(new FileOutputStream(file));
fileStream.write("sep= " + DATA_SEPARATOR + LINE_SEPARATOR);
} catch (IOException e) {
e.printStackTrace();
fileStream = null;
}
private void writeElements(Object... elements) throws IOException {
if (fileStream != null) {
for (Object o : elements) {
fileStream.write(o.toString());
fileStream.write(DATA_SEPARATOR);
}
fileStream.write(LINE_SEPARATOR);
}
}
writeElements(btDeviceName, btRSSIValue, btMacId) is called from bluetoothScan() method every now and then.
How can I achieve writing beside?

Just put 2 on the same line before writing a LINE_SEPARATOR. Change what's in your writeElements to something like this:
private void writeElements(Object... elements) throws IOException {
if (fileStream != null) {
for (int index = 1; index < elements.length + 1; index++) {
String address = elements[index - 1].toString();
fileStream.write(address);
if(index % 2 == 0) fileStream.write(LINE_SEPARATOR);
else fileStream.write(DATA_SEPARATOR);
}
}
}
Testing:
Object[] elements = new Object[4];
elements[0] = "here";
elements[1] = "are";
elements[2] = "some";
elements[3] = "words";
writeElements(elements);
When opening the file:
here,are
some,words

I need to read a .txt file from a java and write the sorted context to a different .txt file

I have a I/O java file, a SDive file which contains main, a .txt Directory file that has random words in it and a Sorted .txt to return the random words in order ascending to descending. It print all the words in the Sorted but it is not sorted.
//Sort.java
// required for input
import java.io.FileReader;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
// required for output
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
class Sort{
private String[] tArr = new String[100];
public void swap(int j) {
String temp = tArr[j-1];
tArr[j-1] = tArr[j];
tArr[j] = temp;
}
///Bubble sort
public void sort() {
int n = tArr.length;
for(int i = 0; i < n; i++) {
for(int j = 1; j < n-i; j++) {
if(tArr[j-1].compareTo(tArr[j]) > 0) {
swap(j);
}
}
}
}
public void read() {
System.out.println("in read()");
String pwd = System.getProperty("user.dir");
String fileName = pwd + "/directory.txt";
System.out.println("Looking for: " + fileName);
String fileLine = "";
try {
File f = new File(fileName);
if(f.exists()) {
System.out.println("Directory profile found, loading data...");
}
else {
System.out.println("Directory profile not found, loading default...");
return; // done, return back to the caller
}
// Read file
FileReader data = new FileReader(fileName);
// Wrap FileReader with BufferedReader
BufferedReader br = new BufferedReader(data);
//String tmp;
int i=0;
while ((fileLine = br.readLine()) != null) {
tArr[i++] = fileLine;
}
// ok, time to load an existing profile
// close the file
br.close();
} catch (FileNotFoundException fnf) {
System.out.println("File not found: " + fileName);
} catch (IOException ioe) {
System.out.println("Error reading file: " + fileName);
} catch (Exception exc) {
System.out.println("Something went wrong: " + fileName);
}
}
public void write() {
System.out.println("in write()");
String pwd = System.getProperty("user.dir");
String fileName = pwd + "/Sorted.txt";
try {
System.out.println("Writing out to: " + fileName);
File file = new File(fileName);
// creates the file
file.createNewFile();
// create FileWriter object
FileWriter writer = new FileWriter(file);
// output to file
// ADD pIdx, pArr, mood, and anything else here...
for(int i = 0; i < tArr.length; i++) {
writer.write(tArr[i] + "\n");
}
writer.flush();
writer.close();
} catch (IOException ex) {
System.out.println("Error writing to file: " + fileName);
}
}
}
And my main file is SDrive:
class SDriver{
public static void main(String args []){
Sort io = new Sort();
io.read();
io.write();
}
}

You should add the io.sort() method after io.read(); line and just before io.write(); line.
I see you use bubble sort, if you really want to implement your own sorting method take a look at quick sort and merge sort which are much much faster than bubble sort on larger arrays but also harder to implement. Insertion and Selection sort are not as fast as merge or quick but still faster than bubble and still as easy to self implement. Or use Arrays.sort(tArr); if you want to do it quick.

Directory not being recognized

So I have a method that reads all the files in a folder and creates new classes in a List with the variables read from the files. For some reason it doesn't ever get past the if(mainDir.isDirectory()){ part, even though the paths are correct and I double checked the folders were there.
public static void loadIntoClass(String dir, int temp){
try {
File mainDir = new File(dir);
if(mainDir.isDirectory()){ //Checks if the dir is a folder and not a file
String[] fileNames = mainDir.list(); //Grabs a list of all the filenames in the dir
for(int x = 0; x > fileNames.length; x++){ //loops through all the files
File currFile = new File(dir + fileNames[x]); //Creates the object we will be gathering information from
if(currFile.isFile()){ //Checks to make sure the file is a file and not a folder
BufferedReader br = new BufferedReader(new FileReader(currFile));
String line = br.readLine();
int currLoop = 1;
boolean collides = false;
while(line != null){ //Will keep checking files until it reaches a blank line
currLoop ++; //Keeps track of how many times it loops
test = line.split("="); //Splits up the variable from the declaration
String toString = test[0].trim(); //Trims off any extra blank spaces on either side
System.out.println("Reading: " + toString + " on line " + currLoop); //For debugging
String toString2 = test[1].trim(); //Trims the second string
parse[currLoop] = Integer.parseInt(toString2); //Turns the string into an integer then puts it into the array
if(toString.equalsIgnoreCase("Collides")){
if(toString2.equalsIgnoreCase("true")){
collides = true;
}
}
if(toString.equalsIgnoreCase("Image Path")){
//path = toString2;
}
line = br.readLine();
}
if(temp == 1){
types.add(new Type(parse[1], parse[2], parse[3], parse[4], parse[5], parse[6], parse[7]));
}
if(temp == 2){
tiles.add(new Tiles(parse[1], collides, null));
}
if(temp == 3){
abilities.add(new Abilities(parse[1], parse[2], parse[3], parse[4]));
}
br.close();
}
}
}
} catch(Exception e) {
System.err.println("ERROR: " + e);
}
}
After that if I change it some other path like "C:/test" it works only to freeze at the for loop. Here's the declaration:
loadIntoClass("C:/Program Files(x86)/GameNameHere/config/enemies", 1);

The methods isDirectory() and isFile() doe not work if the underlying FS-Objects do not exist.

There are multiple possible issues, which you are not taking into consideration...
Your not checking to see if the dir exists
Your not making sure to close your files in case of an read error (or other associated error)
You making life tough for yourself using File#list, instead use File#listFiles which will return an array of File
Make better use of exceptions...
For example...
public static void loadIntoClass(String dir, int temp) throws IOException {
File mainDir = new File(dir);
if(mainDir.exists) { // Check to see if the abstract path actually exists
if (mainDir.isDirectory()){ //Checks if the dir is a folder and not a file
File[] fileNames = mainDir.listFiles(); //Grabs a list of all the filenames in the dir
//String[] fileNames = mainDir.list(); //Grabs a list of all the filenames in the dir
if (fileNames != null && fileNames.length > 0) {
//for(int x = 0; x > fileNames.length; x++){ //loops through all the files
for(File currFile : fileNames){ //loops through all the files
//File currFile = new File(dir + fileNames[x]); //Creates the object we will be gathering information from
if(currFile.isFile()){ //Checks to make sure the file is a file and not a folder
BufferedReader br = null;
try {
br = new BufferedReader(new FileReader(currFile));
String line = null;
int currLoop = 1;
boolean collides = false;
while((line = br.readLine()) != null){ //Will keep checking files until it reaches a blank line
//...//
}
//...//
// Make sure you make all best attempts to close the reader...
} finally {
try {
br.close();
} catch (Exception exp) {
}
}
}
}
} else {
// You may not care, but...
throw new IOException(dir + " does not contain any files");
}
} else {
throw new IOException(dir + " is not a directory");
}
} else {
throw new IOException(dir + " does not exist");
}
}

Multiple 'if' statements into one outputStream

import java.io.*;
import java.io.File;
import java.io.FilenameFilter;
public class YDSearch{
public void listFiles(String dir) throws IOException{
File directory = new File(dir);
if (!directory.isDirectory()) {
System.out.println("No directory provided");
return;
}
//create a FilenameFilter and override its accept-method
FilenameFilter filefilter = new FilenameFilter() {
public boolean accept(File dir, String name) {
//if the file extension is .mp3 return true, else false
return name.endsWith(".mp3")||name.endsWith(".mp4")||name.endsWith(".3gp")
||name.endsWith(".mov")||name.endsWith(".avi")||name.endsWith(".wmv");
}
};
String[] filenames = directory.list(filefilter);
DataOutputStream output = new DataOutputStream(new FileOutputStream("C:/Users/Jonathan/Desktop/YouDetect/SearchByFileType/AllMediaFiles.dat"));
for (String name : filenames) {
output.writeUTF(dir + name);
}
output.close();
DataInputStream input = new DataInputStream(new FileInputStream("C:/Users/Jonathan/Desktop/YouDetect/SearchByFileType/AllMediaFiles.dat"));
DataOutputStream output2 = new DataOutputStream(new FileOutputStream("C:/Users/Jonathan/Desktop/ReadyForAnalysis.dat"));
for (String name : filenames) {
FileInputStream in = new FileInputStream(input.readUTF());
int byteCounter = 0;
int rowCounter = 0;
long bufferCounter = 0;
if(name.endsWith(".mp3")){
byte[] b = new byte[36];
int read = in.read(b, 0, 36);
if (byteCounter != 1000){
if (rowCounter == 1){
System.out.println("\n");
rowCounter = 0;
}
output2.writeUTF(org.apache.commons.codec.binary.Hex.encodeHexString(b)+ " " + dir + name);
bufferCounter ++;
rowCounter ++;
}else{
byteCounter = 0;
try{
Thread.sleep(200);
}catch(InterruptedException e) {
}
}
}
else if(name.endsWith(".mp4")){
byte[] b = new byte[29];
int read = in.read(b, 0, 29);
if (byteCounter != 1000){
if (rowCounter == 1){
System.out.println("\n");
rowCounter = 0;
}
output2.writeUTF(org.apache.commons.codec.binary.Hex.encodeHexString(b)+ " " + dir + name);
bufferCounter ++;
rowCounter ++;
}else{
byteCounter = 0;
try{
Thread.sleep(200);
}catch(InterruptedException e) {
}
}
}
//System.out.println("====================");
}
output2.close();
input.close();
DataInputStream input2 = new DataInputStream(new FileInputStream("C:/Users/Jonathan/Desktop/ReadyForAnalysis.dat"));
for (String name : filenames) {
System.out.println(input2.readUTF()+"\n");
}
}
public void checkHeaderSC(String allFiles)throws IOException{
}
public static void main(String[] args) throws IOException {
YDSearch YDSearch = new YDSearch();
YDSearch.listFiles("C:/Users/Jonathan/Desktop/YD Tests/1) High Quality/");
YDSearch.listFiles("C:/Users/Jonathan/Desktop/YD Tests/2) Medium Quality/");
YDSearch.listFiles("C:/Users/Jonathan/Desktop/YD Tests/3) Low Quality/");
YDSearch.checkHeaderSC("C:/Users/Jonathan/Desktop/YouDetect/SearchByFileType/ReadyForAnalysis.dat");
}
}
Hey there, having a little issue with the above coding and hoped someone here might be able to help. This is sort of a partial version of the code as the real one has 4 more if/else if statements involved.
The program compiles and begins to run fine. It produces several results back from the file that is being read into/then out of again in input2 but then stops, produces no more results and gives the error:
Exception in thread "main" java.io.EOFException
at java.io.DataInputStream.readUnsignedShort(DataInputStream.java:323)
at java.io.DataInputStream.readUTF(DataInputStream.java:572)
at java.io.DataInputStream.readUTF(DataInputStream.java:547)
at YDSearch.listFiles(YDSearch.java:85)
at YDSearch.main(YDSearch.java:93)
Anybody know why this might be happening and have a solution they could share?
I've also tried making the variable 'b' to be inside of an if statement but that doesn't work because of scope. If b was defined by if's then there would only need to be one if statement to output to the file
Please let me know if you've got any ideas, I'd really appreciate it :)

As far as I can see, you don't always put out an output record for every name, only for when the name matches one of your patterns. However, you do try to read an input record for every name.
Ergo, if you have any filenames that don't match the patterns you try to read more than you write, and you will get the EOF.
EDIT:
In more detail, the problem is that you get a list of all the files that end with "mp3", "mp4", "3gp", "mov", "avi or "wmv". You then process that list, and write out something into C:/Users/Jonathan/Desktop/ReadyForAnalysis.dat for each "mp3" and "mp4" file. You then assume that for each entry in your list of files, that you will have an entry in ReadyForAnalysis.dat. However, if there are any files ending in "3gp", "mov", "avi or "wmv" then this will not hold true.