package com.btaz.datautil.files;
import com.btaz.datautil.DataUtilDefaults;
import com.btaz.datautil.DataUtilException;
import java.io.*;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
/**
* User: msundell
*/
public class FileSorter {
/**
* This method sorts every file in a list of input files
* @param sortDir directory to provide the sorting in. If null, then system temp directory is used.
* @param files files to sort
* @param comparator comparator to use for sorting
*/
public static List<File> sort(File sortDir, List<File> files, Comparator<String> comparator) {
// validations
if(sortDir == null) {
throw new DataUtilException("The sort directory parameter can't be a null value");
} else if(!sortDir.exists()) {
throw new DataUtilException("The sort directory doesn't exist");
}
if(files == null) {
throw new DataUtilException("The files parameter can't be a null value");
}
// sort files
List<File> sortedFiles = new ArrayList<File>();
for(File file : files) {
FileInputStream inputStream = null;
BufferedWriter writer = null;
try {
// readLine part into memory
ArrayList<String> list = new ArrayList<String>();
inputStream = new FileInputStream(file);
BufferedReader br = new BufferedReader(new InputStreamReader(inputStream, DataUtilDefaults.charSet));
String line;
while((line = br.readLine()) != null) {
list.add(line);
}
inputStream.close();
inputStream = null;
// sort
Collections.sort(list, comparator);
// write sorted partial
File sortedFile = File.createTempFile("sorted-", ".part", sortDir);
sortedFiles.add(sortedFile);
writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(
sortedFile.getAbsoluteFile(), false),DataUtilDefaults.charSet));
for(String item : list) {
writer.write(item + DataUtilDefaults.lineTerminator);
}
writer.flush();
writer.close();
writer = null;
} catch (FileNotFoundException e) {
throw new DataUtilException(e);
} catch (UnsupportedEncodingException e) {
throw new DataUtilException(e);
} catch (IOException e) {
throw new DataUtilException(e);
} finally {
if(inputStream != null) {
try {
inputStream.close();
} catch (IOException e) {
// intentionally, do nothing
}
}
if(writer != null) {
try {
writer.close();
} catch (IOException e) {
// intentionally, do nothing
}
}
}
}
return sortedFiles;
}
}