Develop Reference

Encoding with UTF-16 in Java

I'm trying to read/write a .txt file in UTF-16 so that I can input/output Japanese characters into/from my program. I have read many similar questions, articles and the Java Docs, virtually copied their code and still can't figure out where I am going wrong. If I output it to the console, or whenever I check the contents of the file (using the correct encoding) all I see is a '?' in place of 'あ'.
Application class:
public class App {
public static void main(String[] args) {
String[] s = {"あ"}; //A test String array
FileReader.write("unicode.txt", "UTF-16", s, false);
System.out.println("File: " + FileReader.read("unicode.txt", "UTF-16") + " Hard-coded example: あ");
}
}
FileReader class:
import java.io.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.nio.charset.Charset;
public class FileReader {
public static String[] read(String fileName, String encoding) {
ArrayList<String> content = new ArrayList<String>();
try(BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(fileName), Charset.forName(encoding).newDecoder()))) {
for(String s = reader.readLine(); s != null; s = reader.readLine()) {
content.add(s);
}
reader.close();
} catch(IOException e) {
System.out.println("An IOException(Input) has been thrown.");
e.printStackTrace();
}
return convertToStringArray(content);
}
public static void write(String fileName, String encoding, String[] content, boolean append) {
try(BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(fileName, append), Charset.forName(encoding).newEncoder()))) {
for(String s : content) {
writer.write(s);
writer.newLine();
}
writer.close();
} catch (IOException e) {
System.out.println("An IOException(appending=" + append + ") has been thrown.");
e.printStackTrace();
}
}
private static String[] convertToStringArray(ArrayList<String> list) {
String[] array = new String[list.size()];
list.toArray(array);
return array;
}
}

reading in a file from computer and editing it and saving as a new file

I am trying to load in a file from my computer with all the words of the dictionary in the file.
When I load the file i put the words into an array of strings.
I then want to eliminate all words that have more than 9 letters in them.
I then want to save the words that are 9 letters or smaller into another separate text file.
When i try to open the new file it only has 9 words in it, yet my print to the screen on eclipse will print the all words of nine or less letters.
Can anyone help!
This is a program that was gave to me as part of the question.
import java.io.*;
public class FileIO{
public String[] load(String file) {
File aFile = new File(file);
StringBuffer contents = new StringBuffer();
BufferedReader input = null;
try {
input = new BufferedReader( new FileReader(aFile) );
String line = null;
int i = 0;
while (( line = input.readLine()) != null){
contents.append(line);
i++;
contents.append(System.getProperty("line.separator"));
}
}
catch (FileNotFoundException ex) {
System.out.println("Can't find the file - are you sure the file is in this location: "+file);
ex.printStackTrace();
}
catch (IOException ex){
System.out.println("Input output exception while processing file");
ex.printStackTrace();
}
finally {
try {
if (input!= null) {
input.close();
}
}
catch (IOException ex) {
System.out.println("Input output exception while processing file");
ex.printStackTrace();
}
}
String[] array = contents.toString().split("\n");
for(String s: array){
s.trim();
}
return array;
}
public void save(String file, String[] array) throws FileNotFoundException, IOException {
File aFile = new File(file);
Writer output = null;
try {
output = new BufferedWriter( new FileWriter(aFile) );
for(int i=0;i<array.length;i++){
output.write( array[i] );
output.write(System.getProperty("line.separator"));
}
}
finally {
if (output != null) output.close();
}
}
}
this is the class i tried to use
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.*;
public class countdown{
public static void main(String args[]){
FileIO reader = new FileIO();
Scanner scan = new Scanner(System.in);
String[] inputs = reader.load("C:/Users/Sony/Documents/dict.csv"); //Reading the File as a String array from a file called dict
String[] input = new String[inputs.length]; //new String array for strings less than 9 letters
for(int i=0;i<inputs.length;i++){
if(inputs[i].length()<=9) { //if string of index i is less than 9
input[i]=inputs[i]; //add it to the new array called input
System.out.println(input[i]); //print line to check
}
}
try{
reader.save("C:/Users/Sony/Documents/dictnew.csv",input);
//this is where i save it to the new file called dictnew.
}catch (Exception e){
System.out.println(e.getClass());
}
}
}

After reading how you want you can split rest logic remains same.
package com.srijan.playground;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
public class FilterLengthWords {
public static void main(String[] args) throws IOException {
BufferedReader br = null;
BufferedWriter bw = null;
try {
br = new BufferedReader(new FileReader("Sample.txt"));
bw = new BufferedWriter(new FileWriter("Output.txt"));
String tmp = null;
while((tmp=br.readLine())!=null) {
if(tmp.length()<=9) {
bw.write(tmp);
}
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
if(br!=null) {
br.close();
br=null;
}
if(bw!=null){
bw.close();
bw=null;
}
}
}
}
Thanks

Take numbers from a file and sort them

I need to make my program read a file, then take the numbers in the string and sort them into an array. I can get my program to read the file and put it to a string, but that's where I'm stuck. All the numbers are on different lines in the file, but appear as one long number in the string. This is what I have so far:
public static void main(String[] args) {
String ipt1;
Scanner fileInput;
File inFile = new File("input1.dat");
try {
fileInput = new Scanner(inFile);
//Reads file contents
while (fileInput.hasNext()) {
ipt1 = fileInput.next();
System.out.print(ipt1);
}
fileInput.close();
}
catch (FileNotFoundException e) {
System.out.println(e);
}
}

I recommend reading the values in as numeric types using fileInput.nextInt() or whatever type you want them, putting them in an array and using a built in sort like Arrays.sort. Unless I'm missing a more subtle point about the question.

If your task is just to get input from some file and you're sure the file has integers, use an ArrayList.
import java.util.*;
Scanner fileInput;
ArrayList<Double>ipt1 = new ArrayList<Double>();
File inFile = new File("input1.dat");
try {
fileInput = new Scanner(inFile);
//Reads file contents
while (fileInput.hasNext()){
ipt1.add(fileInput.nextDouble()); //Adds the next Double to the ArrayList
System.out.print(ipt1.get(ipt1.size()-1)); //Prints out what you just got.
}
fileInput.close();
}
catch (FileNotFoundException e){
System.out.println(e);
}
//Sorting time
//This uses the built-in Array sorting.
Collections.sort(ipt1);
However, if you DO need to come up with a simple array in the end, but CAN use ArrayLists, you can add the following:
Double actualResult[] = new Double[ipt1.size()]; //Declare array
for(int i = 0; i < ipt1.size(); ++i){
actualResult[i] = ipt1.get(i);
}
Arrays.sort(actualResult[]);

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.time.LocalDateTime;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;
public class SortNumberFromFile {
public static void main(String[] args) throws IOException {
BufferedReader br = null;
try {
System.out.println("Started at " + LocalDateTime.now());
br = new BufferedReader(new FileReader("/folder/fileName.csv"));//Read data from file named /folder/fileName.csv
List<Long> collect = br.lines().mapToLong(a -> Long.parseLong(a)).boxed().collect(Collectors.toList());//Collect all read data in list object
Collections.sort(collect);//Sort the data
writeRecordsToFile(collect, "/folder/fileName.txt");//Write sorted data to file named /folder/fileName.txt
System.out.println("Ended at " + LocalDateTime.now());
}
finally {
br.close();
}
}
public static <T> void writeRecordsToFile(Collection<? extends T> items, String filePath) {
BufferedWriter writer = null;
File file = new File(filePath);
try {
if(!file.exists()) {
file.getParentFile().mkdirs();
file.createNewFile();
}
writer = new BufferedWriter(new FileWriter(filePath, true));
if(items != null && items.size() > 0) {
for(T eachItem : items) {
if(eachItem != null) {
writer.write(eachItem.toString());
writer.newLine();
}
}
}
} catch (IOException ex) {
}finally {
try {
writer.close();
} catch (IOException e) {
}
}
}
}

FileReader and BufferedReader

I have 3 methods
for open file
for read file
for return things read in method read
this my code :
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package javaapplication56;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.rmi.RemoteException;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
*
* #author x
*/
public class RemoteFileObjectImpl extends java.rmi.server.UnicastRemoteObject implements RemoteFileObject
{
public RemoteFileObjectImpl() throws java.rmi.RemoteException {
super();
}
File f = null;
FileReader r = null;
BufferedReader bfr = null;
String output = "";
public void open(String fileName) {
//To read file passWord
f = new File(fileName);
}
public String readLine() {
try {
String temp = "";
String newLine = System.getProperty("line.separator");
r = new FileReader(f);
while ((temp = bfr.readLine()) != null) {
output += temp + newLine;
bfr.close();
}
}
catch (IOException ex) {
ex.printStackTrace();
}
return output;
}
public void close() {
try {
bfr.close();
} catch (IOException ex) {
}
}
public static void main(String[]args) throws RemoteException{
RemoteFileObjectImpl m = new RemoteFileObjectImpl();
m.open("C:\\Users\\x\\Documents\\txt.txt");
m.readLine();
m.close();
}
}
But it does not work.

What do you expect it to do, you are not doing anything with the line you read, just
m.readLine();
Instead:
String result = m.readLine();
or use the output variable that you saved.
Do you want to save it to a variable, print it, write it to another file?
Update: after your update in the comments:
Your variable bfr is never created/initialized. You are only doing this:
r = new FileReader(f);
so bfr is still null.
You should do something like this instead:
bfr = new BufferedReader(new FileReader(f));

how to read directories in java

simple: how do i read the contents of a directory in Java, and save that data in an array or variable of some sort? secondly, how do i open an external file in Java?

You can use java IO API. Specifically java.io.File, java.io.BufferedReader, java.io.BufferedWriter etc.
Assuming by opening you mean opening file for reading. Also for good understanding of Java I/O functionalities check out this link: http://download.oracle.com/javase/tutorial/essential/io/
Check the below code.
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
public class FileIO
{
public static void main(String[] args)
{
File file = new File("c:/temp/");
// Reading directory contents
File[] files = file.listFiles();
for (int i = 0; i < files.length; i++) {
System.out.println(files[i]);
}
// Reading conetent
BufferedReader reader = null;
try {
reader = new BufferedReader(new FileReader("c:/temp/test.txt"));
String line = null;
while(true)
{
line = reader.readLine();
if(line == null)
break;
System.out.println(line);
}
}catch(Exception e) {
e.printStackTrace();
}finally {
if(reader != null)
{
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}

You can use a class java.io.File to do that. A File is an abstract representation of file and directory pathnames. You can retrieve the list of files/directories within it using the File.list() method.

There's also the Commons IO package which has a variety of methods for manipulating files and directories.
import java.io.File;
import java.io.IOException;
import java.util.Collection;
import org.apache.commons.io.FileUtils;
import org.apache.commons.io.filefilter.FileFilterUtils;
public class CommonsIO
{
public static void main( String[] args )
{
// Read the contents of a file into a String
try {
String contents = FileUtils.readFileToString( new File( "/etc/mtab" ) );
} catch (IOException e) {
e.printStackTrace();
}
// Get a Collection of files in a directory without looking in subdirectories
Collection<File> files = FileUtils.listFiles( new File( "/home/ross/tmp" ), FileFilterUtils.trueFileFilter(), null );
for ( File f : files ) {
System.out.println( f.getName() );
}
}
}

public class StackOverflow {
public static void main(String[] sr) throws IOException{
//Read a folder and files in it
File f = new File("D:/workspace");
if(!f.exists())
System.out.println("No File/Dir");
if(f.isDirectory()){// a directory!
for(File file :f.listFiles()){
System.out.println(file.getName());
}
}
//Read a file an save content to a StringBuiilder
File f1 = new File("D:/workspace/so.txt");
BufferedReader br = new BufferedReader(new FileReader(f1));
StringBuilder sb = new StringBuilder();
String line = "";
while((line=br.readLine())!=null)
sb.append(line+"\n");
System.out.println(sb);
}
}