Develop Reference

how to read a value in CSV with the value left to it

I have searched in stack and web a lot, for parsing a CSV file.
But I won't get what I want.
I have this table in CSV format,
what I want is, if I give the "ID"(which is 0,1,2,3... ) it should return me the value right to it i.e., if i give
"2" it should return me "hello how are you ?".
"4" it should return me "What do you prefer over tea ?"
How to achieve this?
Right now I kept my CSV file in the raw folder.
Any help will be apppreciated

You can save data in CSV as:-
ArrayList<TableData> arrayList=new ArrayList<>();
arrayList.add(new TableData(1,"Hello"));
arrayList.add(new TableData(2,"How are u"));
arrayList.add(new TableData(3,"I am fine"));
arrayList.add(new TableData(4,"Thank You"));
File file;
File root = Environment.getExternalStorageDirectory();
if (root.canWrite()){
File dir = new File (root.getAbsolutePath() + "/PersonData");
dir.mkdirs();
file = new File(dir, "Data.csv");
FileOutputStream out = null;
try {
// write to byte array
ByteArrayOutputStream baos = new ByteArrayOutputStream();
DataOutputStream dos = new DataOutputStream(baos);
for (TableData element : arrayList) {
dos.writeUTF(String.valueOf(element.id));
dos.writeUTF(String.valueOf(element.name));
}
byte[] bytes = baos.toByteArray();
out = new FileOutputStream(file);
out.write(bytes);
out.close();
}catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
And Retrive it as:-
File file;
File root = Environment.getExternalStorageDirectory();
File dir = new File (root.getAbsolutePath() + "/PersonData");
dir.mkdirs();
file = new File(dir, "Data.csv");
Uri u1 = null;
u1 = Uri.fromFile(file);
try {
FileInputStream inputStream=new FileInputStream(file);
String input="2";
String previousValue="";
ByteArrayInputStream bais = new ByteArrayInputStream(readFully(inputStream));
DataInputStream in = new DataInputStream(bais);
while (in.available() > 0) {
String element = in.readUTF();
if(previousValue.equalsIgnoreCase(input)){
textView.setText(element);
}
previousValue=element;
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
Method to convert inputStream to byte[]:-
public static byte[] readFully(InputStream input) throws IOException
{
byte[] buffer = new byte[8192];
int bytesRead;
ByteArrayOutputStream output = new ByteArrayOutputStream();
while ((bytesRead = input.read(buffer)) != -1)
{
output.write(buffer, 0, bytesRead);
}
return output.toByteArray();
}

Create a separate class for reading CSV file as:-
public class CSVFile {
InputStream inputStream;
public CSVFile(InputStream inputStream){
this.inputStream = inputStream;
}
public List read(){
List resultList = new ArrayList();
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
try {
String csvLine;
while ((csvLine = reader.readLine()) != null) {
String[] row = csvLine.split(",");
resultList.add(row);
}
}
catch (IOException ex) {
throw new RuntimeException("Error in reading CSV file: "+ex);
}
finally {
try {
inputStream.close();
}
catch (IOException e) {
throw new RuntimeException("Error while closing input stream: "+e);
}
}
return resultList;
}
}
Now call this in your activity:-
String input="2";
InputStream inputStream = getResources().openRawResource(R.raw.sample);
CSVFile csvFile = new CSVFile(inputStream);
List scoreList = csvFile.read();
for(int i=0;i<scoreList.size();i++){
Object data_list=scoreList.get(i);
String a[]= (String[]) data_list;
String id=a[0];
String value=a[1];
if(input.equalsIgnoreCase(id)){
Log.d("TAG", "Value Found "+value);
}
}

NoOutputStreamException during image upload in vaadin

Trying to upload only images. The problem is that I don't know how to handle this situation.
#Override
public OutputStream receiveUpload(String filename, String mimeType) {
FileOutputStream fos = null;
if(mimeType.startsWith("image")) {
picture = new Picture();
picture.filename = filename;
picture.mimeType = mimeType;
picture = HibernateUtils.save(picture);
product.pictures.add(picture);
File dirs = new File(IMAGE_LOCATION);
File file = new File(IMAGE_LOCATION + picture.id);
if (!dirs.exists()) {
dirs.mkdirs();
}
try {
fos = new FileOutputStream(file);
} catch (FileNotFoundException e) {
throw new RuntimeException(e);
}
} else {
Notification.show("", Notification.Type.ERROR_MESSAGE);
}
return fos;
}
The problem is that the fos variable will be null if I try to upload different type of files than image. The question is that, how should I handle it?

I'd do something like this:
...
} else {
Notification.show("", Notification.Type.ERROR_MESSAGE);
return new ByteArrayOutputStream();
}
...

GZIP compression to a byte array

I am trying to write a class that can compress data. The below code fails (no exception is thrown, but the target .gz file is empty.)
Besides: I don't want to generate the .gz file directly like it is done in all examples. I only want to get the compressed
data, so that I can e.g. encrypt it before writting the data to a file.
If I write directly to a file everything works fine:
import java.io.*;
import java.util.zip.*;
import java.nio.charset.*;
public class Zipper
{
public static void main(String[] args)
{
byte[] dataToCompress = "This is the test data."
.getBytes(StandardCharsets.ISO_8859_1);
GZIPOutputStream zipStream = null;
FileOutputStream fileStream = null;
try
{
fileStream = new FileOutputStream("C:/Users/UserName/Desktop/zip_file.gz");
zipStream = new GZIPOutputStream(fileStream);
zipStream.write(dataToCompress);
fileStream.write(compressedData);
}
catch(Exception e)
{
e.printStackTrace();
}
finally
{
try{ zipStream.close(); }
catch(Exception e){ }
try{ fileStream.close(); }
catch(Exception e){ }
}
}
}
But, if I want to 'bypass' it to the byte array stream it does not produce a single byte - compressedData is always empty.
import java.io.*;
import java.util.zip.*;
import java.nio.charset.*;
public class Zipper
{
public static void main(String[] args)
{
byte[] dataToCompress = "This is the test data."
.getBytes(StandardCharsets.ISO_8859_1);
byte[] compressedData = null;
GZIPOutputStream zipStream = null;
ByteArrayOutputStream byteStream = null;
FileOutputStream fileStream = null;
try
{
byteStream = new ByteArrayOutputStream(dataToCompress.length);
zipStream = new GZIPOutputStream(byteStream);
zipStream.write(dataToCompress);
compressedData = byteStream.toByteArray();
fileStream = new FileOutputStream("C:/Users/UserName/Desktop/zip_file.gz");
fileStream.write(compressedData);
}
catch(Exception e)
{
e.printStackTrace();
}
finally
{
try{ zipStream.close(); }
catch(Exception e){ }
try{ byteStream.close(); }
catch(Exception e){ }
try{ fileStream.close(); }
catch(Exception e){ }
}
}
}

The problem is that you are not closing the GZIPOutputStream. Until you close it the output will be incomplete.
You just need to close it before reading the byte array. You need to reorder the finally blocks to achieve this.
import java.io.*;
import java.util.zip.*;
import java.nio.charset.*;
public class Zipper
{
public static void main(String[] args)
{
byte[] dataToCompress = "This is the test data."
.getBytes(StandardCharsets.ISO_8859_1);
try
{
ByteArrayOutputStream byteStream =
new ByteArrayOutputStream(dataToCompress.length);
try
{
GZIPOutputStream zipStream =
new GZIPOutputStream(byteStream);
try
{
zipStream.write(dataToCompress);
}
finally
{
zipStream.close();
}
}
finally
{
byteStream.close();
}
byte[] compressedData = byteStream.toByteArray();
FileOutputStream fileStream =
new FileOutputStream("C:/Users/UserName/Desktop/zip_file.gz");
try
{
fileStream.write(compressedData);
}
finally
{
try{ fileStream.close(); }
catch(Exception e){ /* We should probably delete the file now? */ }
}
}
catch(Exception e)
{
e.printStackTrace();
}
}
}
I do not recommend inititalizing the stream variables to null, because it means your finally block can also throw a NullPointerException.
Also note that you can declare main to throw IOException (then you would not need the outermost try statement.)
There is little point in swallowing exceptions from zipStream.close();, because if it throws an exception you will not have a valid .gz file (so you should not proceed to write it.)
Also I would not swallow exceptions from byteStream.close(); but for a different reason - they should never be thrown (i.e. there is a bug in your JRE and you would want to know about that.)

I've improved JITHINRAJ's code - used try-with-resources:
private static byte[] gzipCompress(byte[] uncompressedData) {
byte[] result = new byte[]{};
try (ByteArrayOutputStream bos = new ByteArrayOutputStream(uncompressedData.length);
GZIPOutputStream gzipOS = new GZIPOutputStream(bos)) {
gzipOS.write(uncompressedData);
// You need to close it before using bos
gzipOS.close();
result = bos.toByteArray();
} catch (IOException e) {
e.printStackTrace();
}
return result;
}
private static byte[] gzipUncompress(byte[] compressedData) {
byte[] result = new byte[]{};
try (ByteArrayInputStream bis = new ByteArrayInputStream(compressedData);
ByteArrayOutputStream bos = new ByteArrayOutputStream();
GZIPInputStream gzipIS = new GZIPInputStream(bis)) {
byte[] buffer = new byte[1024];
int len;
while ((len = gzipIS.read(buffer)) != -1) {
bos.write(buffer, 0, len);
}
result = bos.toByteArray();
} catch (IOException e) {
e.printStackTrace();
}
return result;
}

If you are still looking an answer you can use the below code to get the compressed byte[] using deflater and decompress it using inflater.
public static void main(String[] args) {
//Some string for testing
String sr = new String("fsdfesfsfdddddddsfdsfssdfdsfdsfdsfdsfdsdfggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggghghghghggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggfsdfesfsfdddddddsfdsfssdfdsfdsfdsfdsfdsdfggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggghghghghggggggggggggggggggggggggggggggggggggggggg");
byte[] data = sr.getBytes();
System.out.println("src size "+data.length);
try {
compress(data);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public static byte[] compress(byte[] data) throws IOException {
Deflater deflater = new Deflater();
deflater.setInput(data);
ByteArrayOutputStream outputStream = new ByteArrayOutputStream(data.length);
deflater.finish();
byte[] buffer = new byte[1024];
while (!deflater.finished()) {
int count = deflater.deflate(buffer);
outputStream.write(buffer, 0, count);
}
outputStream.close();
byte[] output = outputStream.toByteArray();
System.out.println("Original: " + data.length );
System.out.println("Compressed: " + output.length );
return output;
}

To compress
private static byte[] compress(byte[] uncompressedData) {
ByteArrayOutputStream bos = null;
GZIPOutputStream gzipOS = null;
try {
bos = new ByteArrayOutputStream(uncompressedData.length);
gzipOS = new GZIPOutputStream(bos);
gzipOS.write(uncompressedData);
gzipOS.close();
return bos.toByteArray();
} catch (IOException e) {
e.printStackTrace();
}
finally {
try {
assert gzipOS != null;
gzipOS.close();
bos.close();
}
catch (Exception ignored) {
}
}
return new byte[]{};
}
To uncompress
private byte[] uncompress(byte[] compressedData) {
ByteArrayInputStream bis = null;
ByteArrayOutputStream bos = null;
GZIPInputStream gzipIS = null;
try {
bis = new ByteArrayInputStream(compressedData);
bos = new ByteArrayOutputStream();
gzipIS = new GZIPInputStream(bis);
byte[] buffer = new byte[1024];
int len;
while((len = gzipIS.read(buffer)) != -1){
bos.write(buffer, 0, len);
}
return bos.toByteArray();
} catch (IOException e) {
e.printStackTrace();
}
finally {
try {
assert gzipIS != null;
gzipIS.close();
bos.close();
bis.close();
}
catch (Exception e) {
e.printStackTrace();
}
}
return new byte[]{};
}

You can use the below function, it is tested and working fine.
In general, your code has serious problem of ignoring the exceptions! returning null or simply not printing anything in the catch block will make it very difficult to debug
You do not have to write the zip output to a file if you want to process it further (e.g. encrypt it), you can easily modify the code to write the output to in-memory stream
public static String zip(File inFile, File zipFile) throws IOException {
FileInputStream fis = new FileInputStream(inFile);
FileOutputStream fos = new FileOutputStream(zipFile);
ZipOutputStream zout = new ZipOutputStream(fos);
try {
zout.putNextEntry(new ZipEntry(inFile.getName()));
byte[] buffer = new byte[BUFFER_SIZE];
int len;
while ((len = fis.read(buffer)) > 0) {
zout.write(buffer, 0, len);
}
zout.closeEntry();
} catch (Exception ex) {
ex.printStackTrace();
return null;
} finally {
try{zout.close();}catch(Exception ex){ex.printStackTrace();}
try{fis.close();}catch(Exception ex){ex.printStackTrace();}
}
return zipFile.getAbsolutePath();
}

Most of the examples have wrong exception handling.
public static byte[] gzipBytes(byte[] payload) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
try (GZIPOutputStream gzip = new GZIPOutputStream(baos)) {
gzip.write(payload);
} catch (IOException e) {
throw new UncheckedIOException(e);
}
// note: toByteArray should be called after try-with-resources, not inside
return baos.toByteArray();
}
public static byte[] gunzipBytes(byte[] gzPayload) {
ByteArrayInputStream bais = new ByteArrayInputStream(gzPayload);
try (GZIPInputStream gzip = new GZIPInputStream(bais)) {
// java 9+ required for this method
return gzip.readAllBytes();
} catch (IOException e) {
throw new UncheckedIOException("Error while unpacking gzip content", e);
}
}

Try with this code..
try {
String inputFileName = "test.txt"; //may use your file_Path
String zipFileName = "compressed.zip";
//Create input and output streams
FileInputStream inStream = new FileInputStream(inputFileName);
ZipOutputStream outStream = new ZipOutputStream(new FileOutputStream(zipFileName));
// Add a zip entry to the output stream
outStream.putNextEntry(new ZipEntry(inputFileName));
byte[] buffer = new byte[1024];
int bytesRead;
//Each chunk of data read from the input stream
//is written to the output stream
while ((bytesRead = inStream.read(buffer)) > 0) {
outStream.write(buffer, 0, bytesRead);
}
//Close zip entry and file streams
outStream.closeEntry();
outStream.close();
inStream.close();
} catch (IOException ex) {
ex.printStackTrace();
}
Also may be helpful this one..
http://www.java-samples.com/java/zip_files_in_a_folder_using_java.htm

Moving DB to SDCard [duplicate]

I'm using the code below to try and move my database file to my sdcard. I have no problems except that I get a redline under sd. Any ideas?
File data = Environment.getDataDirectory();
if (sd.canWrite()) {
String currentDBPath = "\\data\\application.package\\databases\\name";
String backupDBPath = "name";
File currentDB = new File(data, currentDBPath);
File backupDB = new File(sd, backupDBPath);
if (currentDB.exists()) {
FileChannel src;
try {
src = new FileInputStream(currentDB).getChannel();
FileChannel dst = new FileOutputStream(backupDB).getChannel();
try {
dst.transferFrom(src, 0, src.size());
src.close();
dst.close();
} catch (IOException e) {
e.printStackTrace();
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}

You can only use a variable if you create an instance of it:
Put this before your code:
File sd = Environment.getExternalStorageDirectory();

if you are using SQLite database try this:
public class _DBHelper extends SQLiteOpenHelper {
public boolean backUp() throws Exception
{
InputStream input = null;
OutputStream output = null;
try {
SQLiteDatabase db = this.getReadableDatabase();
String strSource = db.getPath();
String strDest = Utilities.getAppDocumentsFolder(_context) + "/"
+ DATABASE_NAME;
File fileDest = new File(strDest);
if (fileDest.exists())
{
fileDest.delete();
}
input = new FileInputStream(strSource);
output = new FileOutputStream(strDest);
byte[] buffer = new byte[1024];
int length;
while ((length = input.read(buffer)) > 0) {
output.write(buffer, 0, length);
}
} catch (Exception e) {
throw e;
} finally
{
if (output != null)
{
output.flush();
output.close();
}
if (input != null)
{
input.close();
}
}
return true;
}
}

Moving my db to sd card not working

I'm using the code below to try and move my database file to my sdcard. I have no problems except that I get a redline under sd. Any ideas?
File data = Environment.getDataDirectory();
if (sd.canWrite()) {
String currentDBPath = "\\data\\application.package\\databases\\name";
String backupDBPath = "name";
File currentDB = new File(data, currentDBPath);
File backupDB = new File(sd, backupDBPath);
if (currentDB.exists()) {
FileChannel src;
try {
src = new FileInputStream(currentDB).getChannel();
FileChannel dst = new FileOutputStream(backupDB).getChannel();
try {
dst.transferFrom(src, 0, src.size());
src.close();
dst.close();
} catch (IOException e) {
e.printStackTrace();
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}

You can only use a variable if you create an instance of it:
Put this before your code:
File sd = Environment.getExternalStorageDirectory();

if you are using SQLite database try this:
public class _DBHelper extends SQLiteOpenHelper {
public boolean backUp() throws Exception
{
InputStream input = null;
OutputStream output = null;
try {
SQLiteDatabase db = this.getReadableDatabase();
String strSource = db.getPath();
String strDest = Utilities.getAppDocumentsFolder(_context) + "/"
+ DATABASE_NAME;
File fileDest = new File(strDest);
if (fileDest.exists())
{
fileDest.delete();
}
input = new FileInputStream(strSource);
output = new FileOutputStream(strDest);
byte[] buffer = new byte[1024];
int length;
while ((length = input.read(buffer)) > 0) {
output.write(buffer, 0, length);
}
} catch (Exception e) {
throw e;
} finally
{
if (output != null)
{
output.flush();
output.close();
}
if (input != null)
{
input.close();
}
}
return true;
}
}