Develop Reference

How to store an ArrayList in a file?

I have a class which represents an ArrayList stored in a file, because I need an ArrayList with multiple gigabytes of data in it which is obviously too large to be stored in memory. The data is represented by a class called Field and the function Field.parse() is just for converting the Field into a String and the other way.
The Field class stores a list of (strange) chess pieces and their coordinates.
My class is working fine, but it takes a long time to add an element to the file and I need my program to run as fast as possible. Does anyone know a more efficient/faster way of doing things?
Also, I am not allowed to use external libraries/apis. Please keep that in mind.
This is the class which is responsible for storing Field objects in a temp file:
private File file;
private BufferedReader reader;
private BufferedWriter writer;
public FieldSaver() {
try {
file = File.createTempFile("chess-moves-", ".temp");
System.out.println(file.getAbsolutePath());
} catch (IOException e) {
e.printStackTrace();
}
}
public void add(Field field) {
try {
File temp = File.createTempFile("chess-moves-", ".temp");
writer = new BufferedWriter(new FileWriter(temp));
reader = new BufferedReader(new FileReader(file));
String line;
while((line = reader.readLine()) != null ) {
writer.write(line);
writer.newLine();
}
reader.close();
writer.write(field.parse());
writer.close();
file.delete();
file = new File(temp.getAbsolutePath());
} catch (IOException e) {
e.printStackTrace();
}
}
public Field get(int n) {
try {
reader = new BufferedReader(new FileReader(file));
for (int i = 0; i < n; i++) {
reader.readLine();
}
String line = reader.readLine();
reader.close();
return Field.parse(line);
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
And this is the Field class:
private WildBoar wildBoar;
private HuntingDog[] huntingDogs;
private Hunter hunter;
private int size;
#Override
public String toString() {
String result = "Wildschwein: " + wildBoar.toString();
for (HuntingDog dog : huntingDogs) {
result += "; Hund: " + dog.toString();
}
return result + "; Jäger: " + hunter.toString();
}
#Override
public boolean equals(Object obj) {
if (obj instanceof Field) {
Field field = (Field) obj;
HuntingDog[] dogs = field.getHuntingDogs();
return wildBoar.equals(field.getWildBoar()) && hunter.equals(field.getHunter()) && huntingDogs[0].equals(dogs[0]) && huntingDogs[1].equals(dogs[1]) && huntingDogs[2].equals(dogs[2]);
}
return false;
}
public Field(int size, WildBoar wildBoar, HuntingDog[] huntingDogs, Hunter hunter) {
this.size = size;
this.wildBoar = wildBoar;
this.huntingDogs = huntingDogs;
this.hunter = hunter;
}
public WildBoar getWildBoar() {
return wildBoar;
}
public HuntingDog[] getHuntingDogs() {
return huntingDogs;
}
public Hunter getHunter() {
return hunter;
}
public int getSize() {
return size;
}
public static Field parse(String s) {
String[] arr = s.split(",");
WildBoar boar = WildBoar.parse(arr[0]);
Hunter hunter = Hunter.parse(arr[1]);
HuntingDog[] dogs = new HuntingDog[arr.length - 2];
for(int i = 2; i < arr.length; i++) {
dogs[i - 2] = HuntingDog.parse(arr[i]);
}
return new Field(8, boar, dogs, hunter);
}
public String parse() {
String result = wildBoar.parse() + "," + hunter.parse();
for(HuntingDog dog : huntingDogs) {
result += "," + dog.parse();
}
return result;
}

Here's an MCVE to do what you want, based on the information you provided.
You can run it and see that it can save a Field to the file and get a Field by index very quickly.
The Fields are constant length, so you can get a Field by index by going to byte offset of index times field length in bytes. This would be significantly more difficult if the field were not constant length.
import java.io.Closeable;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;
public class FieldSaver implements Closeable {
public static void main(String[] args) throws IOException {
File f = File.createTempFile("chess-moves-", ".temp");
try (FieldSaver test = new FieldSaver(f);) {
for (byte i = 0; i < 100; i++) {
test.add(new Field(8, new WildBoar(i, i), new Hunter(i, i), new HuntingDog[] {
new HuntingDog(i, i),
new HuntingDog(i, i),
new HuntingDog(i, i) }));
}
// Get a few Fields by index
System.out.println(test.get(0));
System.out.println(test.get(50));
System.out.println(test.get(99));
// EOF exception, there is no Field 100
// System.out.println(test.get(100));
}
}
private final RandomAccessFile data;
public FieldSaver(File f) throws FileNotFoundException {
data = new RandomAccessFile(f, "rw");
}
public void add(Field field) throws IOException {
data.seek(data.length());
field.write(data);
}
public Field get(int index) throws IOException {
data.seek(index * Field.STORAGE_LENGTH_BYTES);
return Field.read(data);
}
public void close() throws IOException { data.close(); }
static abstract class Piece {
protected byte xPos;
protected byte yPos;
public Piece(DataInput data) throws IOException {
xPos = data.readByte();
yPos = data.readByte();
}
public Piece(byte xPos, byte yPos) {
this.xPos = xPos;
this.yPos = yPos;
}
public void write(DataOutput data) throws IOException {
data.writeByte(xPos);
data.writeByte(yPos);
}
public String toString() { return "[" + xPos + ", " + yPos + "]"; }
}
static class Hunter extends Piece {
public Hunter(byte xPos, byte yPos) { super(xPos, yPos); }
public Hunter(DataInput data) throws IOException { super(data); }
}
static class HuntingDog extends Piece {
public HuntingDog(byte xPos, byte yPos) { super(xPos, yPos); }
public HuntingDog(DataInput data) throws IOException { super(data); }
}
static class WildBoar extends Piece {
public WildBoar(byte xPos, byte yPos) { super(xPos, yPos); }
public WildBoar(DataInput data) throws IOException { super(data); }
}
static class Field {
// size of boar + hunter + 3 dogs
public static final int STORAGE_LENGTH_BYTES = 2 + 2 + (3 * 2);
private int size;
private WildBoar boar;
private Hunter hunter;
private final HuntingDog[] dogs;
public Field(int size, WildBoar wildBoar, Hunter hunter, HuntingDog[] huntingDogs) {
this.size = size;
this.boar = wildBoar;
this.hunter = hunter;
this.dogs = huntingDogs;
}
public String toString() {
String result = "Wildschwein: " + boar.toString();
for (HuntingDog dog : dogs) {
result += "; Hund: " + dog.toString();
}
return result + "; Jäger: " + hunter.toString();
}
public static Field read(DataInput data) throws IOException {
WildBoar boar = new WildBoar(data);
Hunter hunter = new Hunter(data);
HuntingDog[] dogs = new HuntingDog[3];
for (int i = 0; i < 3; i++) {
dogs[i] = new HuntingDog(data);
}
return new Field(8, boar, hunter, dogs);
}
public void write(DataOutput data) throws IOException {
boar.write(data);
hunter.write(data);
for (HuntingDog dog : dogs) {
dog.write(data);
}
}
}
}

Use a Map implementation like Cache from ehcache. This library will optimize for you so you don't have to handle writing and reading to disk and manage when to keep it in memory or on disk. You can just use it as a normal map. You probably want a map instead of a list for faster lookup so the library can optimize even more for you.
http://www.ehcache.org/
CacheManager cacheManager = CacheManagerBuilder.newCacheManagerBuilder()
.withCache("preConfigured",
CacheConfigurationBuilder.newCacheConfigurationBuilder(Long.class, String.class,
ResourcePoolsBuilder.heap(100))
.build())
.build(true);
Cache<Long, String> preConfigured
= cacheManager.getCache("preConfigured", Long.class, String.class);

Java - printing all ArrayList elements as a single String

My program prints out a library. Each library is composed of books. Each book is composed of a title and the authors of that book. I have a driver program, a Library class, and a Book class. My issue is that when I use my driver program that uses my toString() methods in the library and book classes to print the library, the authors of each book are appearing as [author, ;, author, ;, author] and I want them to print as author; author; author.
Expected output: http://prntscr.com/810ik2
My output: http://prntscr.com/810ipp
My input: http://prntscr.com/810j6f
getAuthors is the method in my driver program that separates the authors (In the input file that the authors are taken from authors are separated by '*' instead of separated by ';' which is what i need in my output)
Please let me know in the comments if there is too little info, too much info, if what I've given is too confusing, or if I didn't explain anything properly. I'm new to Java and fairly new at posting questions here so please go easy on me. Thank you!
Edit: Just in case here are my three classes (only the important stuff):
Book.java:
import java.util.*;
public class Book implements Comparable<Book>
{
private final String myTitle;
private final ArrayList<String> myAuthors;
public Book(final String theTitle, final ArrayList<String> theAuthors)
{
if (theTitle == "" || theAuthors.isEmpty() ||
theTitle == null || theAuthors.get(0) == null)
{
throw new IllegalArgumentException(
"The book must have a valid title AND author.");
}
else
{
myTitle = theTitle;
myAuthors = new ArrayList<String>();
for (int i = 0; i < theAuthors.size(); i++)
{
myAuthors.add(theAuthors.get(i));
}
}
}
public String toString()
{
String result = "\"" + myTitle + "\" by ";
for (int i = 0; i < myAuthors.size(); i++)
{
result += (String)myAuthors.get(i);
}
return result;
}
}
Library.java:
import java.util.*;
public class Library
{
public Library(final ArrayList<Book> theOther)
{
if (theOther == null)
{
throw new NullPointerException();
}
else
{
myBooks = new ArrayList<Book>();
for (int i = 0; i < theOther.size(); i++)
{
myBooks.add(theOther.get(i));
}
}
}
public ArrayList<Book> findTitles(final String theTitle)
{
ArrayList<Book> titleList = new ArrayList<Book>();
for (int i = 0; i < myBooks.size(); i++)
{
if (myBooks.get(i).getTitle().equals(theTitle))
{
titleList.add(myBooks.get(i));
}
}
return titleList;
}
public String toString()
{
String result = "";
for (int i = 0; i < myBooks.size(); i++)
{
String tempTitle = myBooks.get(i).getTitle();
ArrayList<String> tempAuthors = myBooks.get(i).getAuthors();
Book tempBook = new Book(tempTitle, tempAuthors);
result += (tempBook + "\n");
}
return result;
}
}
LibraryDriver.java:
import java.util.*;
import java.io.*;
public class LibraryDriver
{
public static void main(String[] theArgs)
{
Scanner inputFile = null;
PrintStream outputFile = null;
ArrayList<String> authors = new ArrayList<String>();
ArrayList<Book> books = new ArrayList<Book>();
ArrayList<Book> books2 = new ArrayList<Book>();
String[] filesInputs = new String[]{"LibraryIn1.txt", "LibraryIn2.txt"};
try
{
outputFile = new PrintStream(new File("LibraryOut.txt"));
for (String fileInput : filesInputs)
{
inputFile = new Scanner(new File(fileInput));
while (inputFile.hasNext())
{
String title = "";
String input = inputFile.nextLine();
//Read title
title = input;
input = inputFile.nextLine();
authors = getAuthors(input);
//Insert title & authors into a book
Book tempBook = new Book(title, authors);
//Add this book to the ArrayList<Book> of books
books.add(tempBook);
}
Library myLib = new Library(books);
outputFile.println(myLib);
inputFile.close();
myLib.sort();
outputFile.println(myLib);
}
}
catch (Exception e)
{
System.out.println("Difficulties opening the file! " + e);
System.exit(1);
}
inputFile.close();
outputFile.close();
}
public static ArrayList<String> getAuthors(String theAuthors)
{
int lastAsteriskIndex = 0;
ArrayList<String> authorList = new ArrayList<String>();
for (int i = 0; i < theAuthors.length(); i++)
{
if (theAuthors.charAt(i) == '*')
{
if (lastAsteriskIndex > 0)
{
authorList.add(";");
authorList.add(theAuthors.substring(lastAsteriskIndex + 1, i));
}
else
{
authorList.add(theAuthors.substring(0, i));
}
lastAsteriskIndex = i;
}
}
if (lastAsteriskIndex == 0)
{
authorList.add(theAuthors);
}
return authorList;
}
}

So, I hobbled together a runnable example of your code as best as I could and using
The Hobbit
Tolkien, J.R.R
Acer Dumpling
Doofus, Robert
As input, I get
"The Hobbit" by Tolkien, J.R.R
"Acer Dumpling" by Doofus, Robert
The code:
import java.io.File;
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.Scanner;
public class LibraryDriver {
public static void main(String[] theArgs) {
// ArrayList<Book> books = new ArrayList<>(25);
// books.add(
// new Book("Bananas in pajamas",
// new ArrayList<>(Arrays.asList(new String[]{"B1", "B2"}))));
//
// Library lib = new Library(books);
// System.out.println(lib.toString());
Scanner inputFile = null;
PrintStream outputFile = null;
ArrayList<String> authors = new ArrayList<String>();
ArrayList<Book> books = new ArrayList<Book>();
ArrayList<Book> books2 = new ArrayList<Book>();
String[] filesInputs = new String[]{"LibraryIn1.txt"}; //, "LibraryIn2.txt"};
try {
outputFile = new PrintStream(new File("LibraryOut.txt"));
for (String fileInput : filesInputs) {
inputFile = new Scanner(new File(fileInput));
while (inputFile.hasNext()) {
String title = "";
String input = inputFile.nextLine();
//Read title
title = input;
input = inputFile.nextLine();
authors = getAuthors(input);
//Insert title & authors into a book
Book tempBook = new Book(title, authors);
//Add this book to the ArrayList<Book> of books
books.add(tempBook);
}
Library myLib = new Library(books);
outputFile.println(myLib);
inputFile.close();
// myLib.sort();
// outputFile.println(myLib);
}
} catch (Exception e) {
System.out.println("Difficulties opening the file! " + e);
System.exit(1);
}
inputFile.close();
outputFile.close();
}
public static ArrayList<String> getAuthors(String theAuthors) {
int lastAsteriskIndex = 0;
ArrayList<String> authorList = new ArrayList<String>();
for (int i = 0; i < theAuthors.length(); i++) {
if (theAuthors.charAt(i) == '*') {
if (lastAsteriskIndex > 0) {
authorList.add(";");
authorList.add(theAuthors.substring(lastAsteriskIndex + 1, i));
} else {
authorList.add(theAuthors.substring(0, i));
}
lastAsteriskIndex = i;
}
}
if (lastAsteriskIndex == 0) {
authorList.add(theAuthors);
}
return authorList;
}
public static class Library {
private ArrayList<Book> myBooks;
public Library(final ArrayList<Book> theOther) {
if (theOther == null) {
throw new NullPointerException();
} else {
myBooks = new ArrayList<Book>();
for (int i = 0; i < theOther.size(); i++) {
myBooks.add(theOther.get(i));
}
}
}
public ArrayList<Book> findTitles(final String theTitle) {
ArrayList<Book> titleList = new ArrayList<Book>();
for (int i = 0; i < myBooks.size(); i++) {
if (myBooks.get(i).getTitle().equals(theTitle)) {
titleList.add(myBooks.get(i));
}
}
return titleList;
}
public String toString() {
String result = "";
for (int i = 0; i < myBooks.size(); i++) {
String tempTitle = myBooks.get(i).getTitle();
Book b = myBooks.get(i);
ArrayList<String> tempAuthors = b.getAuthors();
Book tempBook = new Book(tempTitle, tempAuthors);
result += (tempBook + "\n");
}
return result;
}
}
public static class Book implements Comparable<Book> {
private final String myTitle;
private final ArrayList<String> myAuthors;
public Book(final String theTitle, final ArrayList<String> theAuthors) {
if (theTitle == "" || theAuthors.isEmpty()
|| theTitle == null || theAuthors.get(0) == null) {
throw new IllegalArgumentException(
"The book must have a valid title AND author.");
} else {
myTitle = theTitle;
myAuthors = new ArrayList<String>();
for (int i = 0; i < theAuthors.size(); i++) {
myAuthors.add(theAuthors.get(i));
}
}
}
public String toString() {
String result = "\"" + myTitle + "\" by ";
for (int i = 0; i < myAuthors.size(); i++) {
result += (String) myAuthors.get(i);
}
return result;
}
#Override
public int compareTo(Book o) {
throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
}
public String getTitle() {
return myTitle;
}
public ArrayList<String> getAuthors(String theAuthors) {
int lastAsteriskIndex = 0;
ArrayList<String> authorList = new ArrayList<String>();
for (int i = 0; i < theAuthors.length(); i++) {
if (theAuthors.charAt(i) == '*') {
if (lastAsteriskIndex > 0) {
authorList.add(";");
authorList.add(theAuthors.substring(lastAsteriskIndex + 1, i));
} else {
authorList.add(theAuthors.substring(0, i));
}
lastAsteriskIndex = i;
}
}
if (lastAsteriskIndex == 0) {
authorList.add(theAuthors);
}
return authorList;
}
public ArrayList<String> getAuthors() {
return myAuthors;
}
}
}
Consider providing a runnable example which demonstrates your problem. This is not a code dump, but an example of what you are doing which highlights the problem you are having. This will result in less confusion and better responses

Found some code for serialization of an ItemStack in Bukkit, how to deserialize it?

I've dug up the following code for serializing an ItemStack in bukkit (Minecraft). I've been able to serialize an item in hand with the following:
itemString = ItemStackUtils.deserialize(player.getInventory().getItemInHand());
I can't figure out how to utilize the deserial call however. What I am trying to do is to pull an item from the players hand, serialize it, stick it into a config file, then when the player runs another command... deserialize it and slap it into their inventory. I am fairly certain this class will meet my needs if I just can get the last part working.
public final class ItemStackUtils {
public static String getEnchants(ItemStack i){
List<String> e = new ArrayList<String>();
Map<Enchantment, Integer> en = i.getEnchantments();
for(Enchantment t : en.keySet()) {
e.add(t.getName() + ":" + en.get(t));
}
return StringUtils.join(e, ",");
}
public static String deserialize(ItemStack i){
String[] parts = new String[6];
parts[0] = i.getType().name();
parts[1] = Integer.toString(i.getAmount());
parts[2] = String.valueOf(i.getDurability());
parts[3] = i.getItemMeta().getDisplayName();
parts[4] = String.valueOf(i.getData().getData());
parts[5] = getEnchants(i);
return StringUtils.join(parts, ";");
}
public ItemStack deserial(String p){
String[] a = p.split(";");
ItemStack i = new ItemStack(Material.getMaterial(a[0]), Integer.parseInt(a[1]));
i.setDurability((short) Integer.parseInt(a[2]));
ItemMeta meta = i.getItemMeta();
meta.setDisplayName(a[3]);
i.setItemMeta(meta);
MaterialData data = i.getData();
data.setData((byte) Integer.parseInt(a[4]));
i.setData(data);
if (a.length > 5) {
String[] parts = a[5].split(",");
for (String s : parts) {
String label = s.split(":")[0];
String amplifier = s.split(":")[1];
Enchantment type = Enchantment.getByName(label);
if (type == null)
continue;
int f;
try {
f = Integer.parseInt(amplifier);
} catch(Exception ex) {
continue;
}
i.addEnchantment(type, f);
}
}
return i;
}
}

here it saves & loads the whole NBT
package XXXXXXXXX
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import org.apache.commons.lang.StringUtils;
import org.bukkit.Material;
import org.bukkit.craftbukkit.v1_8_R3.inventory.CraftItemStack;
import org.bukkit.enchantments.Enchantment;
import org.bukkit.inventory.ItemStack;
import org.bukkit.inventory.meta.ItemMeta;
import org.bukkit.material.MaterialData;
import net.minecraft.server.v1_8_R3.MojangsonParseException;
import net.minecraft.server.v1_8_R3.MojangsonParser;
import net.minecraft.server.v1_8_R3.NBTTagCompound;
public class ItemSerialize {
public ItemSerialize() {
}
public static String serialize(ItemStack i) {
String[] parts = new String[7];
parts[0] = i.getType().name();
parts[1] = Integer.toString(i.getAmount());
parts[2] = String.valueOf(i.getDurability());
parts[3] = i.getItemMeta().getDisplayName();
parts[4] = String.valueOf(i.getData().getData());
parts[5] = getEnchants(i);
parts[6] = getNBT(i);
return StringUtils.join(parts, ";");
}
public static String getEnchants(ItemStack i) {
List<String> e = new ArrayList<String>();
Map<Enchantment, Integer> en = i.getEnchantments();
for (Enchantment t : en.keySet()) {
e.add(t.getName() + ":" + en.get(t));
}
return StringUtils.join(e, ",");
}
public static String getLore(ItemStack i) {
List<String> e = i.getItemMeta().getLore();
return StringUtils.join(e, ",");
}
public static String getNBT(ItemStack i) {
net.minecraft.server.v1_8_R3.ItemStack nmsStack = CraftItemStack.asNMSCopy(i);
NBTTagCompound compound = nmsStack.hasTag() ? nmsStack.getTag() : new NBTTagCompound();
return compound.toString();
}
public static ItemStack setNBT(ItemStack i, String NBT) {
net.minecraft.server.v1_8_R3.ItemStack nmsStack = CraftItemStack.asNMSCopy(i);
try {
NBTTagCompound compound = MojangsonParser.parse(NBT);
nmsStack.setTag(compound);
} catch (MojangsonParseException e1) {
e1.printStackTrace();
}
return CraftItemStack.asBukkitCopy(nmsStack);
}
#SuppressWarnings("deprecation")
public static ItemStack deserial(String p) {
String[] a = p.split(";");
ItemStack i = new ItemStack(Material.getMaterial(a[0]), Integer.parseInt(a[1]));
i.setDurability((short) Integer.parseInt(a[2]));
ItemMeta meta = i.getItemMeta();
meta.setDisplayName(a[3]);
i.setItemMeta(meta);
MaterialData data = i.getData();
data.setData((byte) Integer.parseInt(a[4]));
i.setData(data);
if (!a[6].isEmpty()) {
i = setNBT(i, a[6]);
}
if (!a[5].isEmpty()) {
String[] parts = a[5].split(",");
for (String s : parts) {
String label = s.split(":")[0];
String amplifier = s.split(":")[1];
Enchantment type = Enchantment.getByName(label);
if (type == null)
continue;
int f;
try {
f = Integer.parseInt(amplifier);
} catch (Exception ex) {
continue;
}
i.addUnsafeEnchantment(type, f);
}
}
return i;
}
}

ItemStack rItem = ItemStackUtils.deserial(itemString);

Using Bubble sort to sort file by surname?

In this program iam able to read a file into an array and split the array. Then i have got an array method to sort the file by surname using bubble sort. However, i get an error. Can someone assist me please.
Error:
error: method BubbleCountry in class StudentSort cannot be applied to given types;
StudentSort.txt
Bren Ramal
Casi Ron
Alba Jordi
SortData file
import java.io.*;
import java.util.*;
class ShowSort implements Comparable {
private String name;
private String surname;
public void setName(String name) {
this.name = name;
}
public String getName() {
return name;
}
public void setSurname(String surname) {
this.surname = surname;
}
public String getSurname() {
return surname;
}
public int compareTo(Object Student) throws ClassCastException {
if (!(Student instanceof ShowSort))
throw new ClassCastException("Error");
String surn = ((ShowSort) Student).getSurname();
return this.surname.compareTo(surn);
}
}
StudentSort file
import java.io.*;
import java.util.*;
public class StudentSort {
StudentSort() {
int j = 0;
ShowSort data[] = new ShowSort[3];
try {
FileInputStream fstream = new FileInputStream("StudentSort.txt");
// Use DataInputStream to read binary NOT text.
BufferedReader br = new BufferedReader(new InputStreamReader(fstream));
String line;
ArrayList list = new ArrayList();
while ((line = br.readLine()) != null) {
list.add(line);
}
Iterator itr;
for (itr = list.iterator(); itr.hasNext();) {
String str = itr.next().toString();
String[] splitSt = str.split("\t");
String name = "", surname = "";
for (int i = 0; i < splitSt.length; i++) {
name = splitSt[0];
surname = splitSt[1];
}
BubbleCountry(surname);//This is the issue.
data[j] = new ShowSort();
data[j].setName(name);
data[j].setSurname(surname);
j++;
}
for (int i = 0; i < 3; i++) {
ShowSort show = data[i];
String name = show.getName();
String surname = show.getSurname();
System.out.println(name + "\t" + surname);
}
} catch (Exception e) {
}
}
private static void BubbleCountry(String[] myarray) {
String ctry;
for(int i=0; i<myarray.length; i++) {
for(int j=0; j<myarray.length-1-i; j++) {
if(myarray[j].compareTo(myarray[j+1])>0) {
ctry= myarray[j];
myarray[j] = myarray[j+1];
myarray[j+1] = ctry;
}
}
}
}
public static void main(String[] args) {
StudentSort data = new StudentSort();
}
}

You are calling BubbleCountry(surname); but its prototype shows
private static void BubbleCountry(String[] myarray)
So the difference is here. The function requires an array of string as argument but while calling you are passing a string rather than string array.
import java.io.*;
import java.util.*;
public class StudentSort
{
StudentSort()
{
int j = 0;
ShowSort data[] = new ShowSort[3];
try
{
FileInputStream fstream = new FileInputStream("StudentSort.txt");
// Use DataInputStream to read binary NOT text.
BufferedReader br = new BufferedReader(new InputStreamReader(fstream));
String line;
ArrayList<String> list = new ArrayList<String>();
while ((line = br.readLine()) != null)
{
list.add(line);
}
Iterator<String> itr = list.iterator();
int k = 0;
for (itr = list.iterator(); itr.hasNext();itr.next())
{
String str = itr.toString();
String[] splitSt = str.split("\t");
data[k].setName(splitSt[0]);
data[k].setName(splitSt[1]);
k++;
}
BubbleCountry(data);//This is the issue.
for (int i = 0; i < 3; i++)
{
ShowSort show = data[i];
String name1 = show.getName();
String surname1 = show.getSurname();
System.out.println(name1 + "\t" + surname1);
}
}
catch (Exception e)
{
}
}
private static void BubbleCountry(ShowSort[] myarray)
{
ShowSort ctry;
for(int i=0; i<myarray.length; i++)
{
for(int j=0; j<myarray.length-1-i; j++)
{
if(myarray[j].compareTo(myarray[j+1])>0)
{
ctry= myarray[j];
myarray[j] = myarray[j+1];
myarray[j+1] = ctry;
}
}
}
}
public static void main(String[] args)
{
StudentSort data = new StudentSort();
}
}

How can i show it at first?

I wrote a simple java application, I have a problem please help me;
I have a file (JUST EXAMPLE):
1.TXT
-------
SET MRED:NAME=MRED:0,MREDID=60;
SET BCT:NAME=BCT:0,NEPE=DCS,T2=5,DK0=KOR;
CREATE LCD:NAME=LCD:0;
-------
and this is my source code
import java.io.IOException;
import java.io.*;
import java.util.StringTokenizer;
class test1 {
private final int FLUSH_LIMIT = 1024 * 1024;
private StringBuilder outputBuffer = new StringBuilder(
FLUSH_LIMIT + 1024);
public static void main(String[] args) throws IOException {
test1 p=new test1();
String fileName = "i:\\1\\1.txt";
File file = new File(fileName);
BufferedReader br = new BufferedReader(new FileReader(file));
String line;
while ((line = br.readLine()) != null) {
StringTokenizer st = new StringTokenizer(line, ";|,");
while (st.hasMoreTokens()) {
String token = st.nextToken();
p.processToken(token);
}
}
p.flushOutputBuffer();
}
private void processToken(String token) {
if (token.startsWith("MREDID=")) {
String value = getTokenValue(token,"=");
outputBuffer.append("MREDID:").append(value).append("\n");
} else if (token.startsWith("DK0=")) {
String value = getTokenValue(token,"=");
outputBuffer.append("DK0=:").append(value).append("\n");
} else if (token.startsWith("NEPE=")) {
String value = getTokenValue(token,"=");
outputBuffer.append("NEPE:").append(value).append("\n");
}
if (outputBuffer.length() > FLUSH_LIMIT) {
flushOutputBuffer();
}
}
private String getTokenValue(String token,String find) {
int start = token.indexOf(find) + 1;
int end = token.length();
String value = token.substring(start, end);
return value;
}
private void flushOutputBuffer() {
System.out.print(outputBuffer);
outputBuffer = new StringBuilder(FLUSH_LIMIT + 1024);
}
}
I want this output :
MREDID:60
DK0=:KOR
NEPE:DCS
But this application show me this :
MREDID:60
NEPE:DCS
DK0=:KOR
please tell me how can i handle this , because of that DK0 must be at first and this is just a sample ; my real application has 14000 lines
Thanks ...

Instead of outputting the value when you read it, put it in a hashmap. Once you've read your entire file, output in the order you want by getting the values from the hashmap.

Use a HashTable to store the values and print from it in the desired order after parsing all tokens.
//initialize hash table
HashTable ht = new HashTable();
//instead of outputBuffer.append, put the values in to the table like
ht.put("NEPE", value);
ht.put("DK0", value); //etc
//print the values after the while loop
System.out.println("MREDID:" + ht.get("MREDID"));
System.out.println("DK0:" + ht.get("DK0"));
System.out.println("NEPE:" + ht.get("NEPE"));

Create a class, something like
class data {
private int mredid;
private String nepe;
private String dk0;
public void setMredid(int mredid) {
this.mredid = mredid;
}
public void setNepe(String nepe) {
this.nepe = nepe;
}
public void setDk0(String dk0) {
this.dk0 = dk0;
}
public String toString() {
String ret = "MREDID:" + mredid + "\n";
ret = ret + "DK0=:" + dk0 + "\n";
ret = ret + "NEPE:" + nepe + "\n";
}
Then change processToken to
private void processToken(String token) {
Data data = new Data();
if (token.startsWith("MREDID=")) {
String value = getTokenValue(token,"=");
data.setMredid(Integer.parseInt(value));
} else if (token.startsWith("DK0=")) {
String value = getTokenValue(token,"=");
data.setDk0(value);
} else if (token.startsWith("NEPE=")) {
String value = getTokenValue(token,"=");
data.setNepe(value);
}
outputBuffer.append(data.toString());
if (outputBuffer.length() > FLUSH_LIMIT) {
flushOutputBuffer();
}
}