File System - Managing Secondary Memory Simulated As Byte Array In Java
Feb 11, 2014
I and a friend are working with a project to create a file system, who manages a secondary memory simulated as a byte array in Java. We want the file system to be a hierarchical tree structure like in UNIX.
We have come quite far, but the paths are not handled correct. I seem to have mistaken the relative folder ./ for the root folder, but it should mean "working directory folder", ie, where I stand now. That is, if I stand in /dir1 as my "working directory" and make mkdir ./dir2 then should dir2 end up as subfolder in dir1. But with me it appears in the root.
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Apr 30, 2014
i have I byte array ,That I was getting from the gps packets , I need to convert that into jpg file
public static void writejpegfile(byte[] someByteArray) throws FileNotFoundException, IOException {
FileOutputStream fos = new FileOutputStream("image" + new Date().getTime() + ".jpg")
try {
[Code]....
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Jan 11, 2014
when running Eclipse, roughly 250k memory is used by it?In my Task Manager, it says: javaw.exe00265,000 KJava(TM) Platform SE binary.The value of 265,000 K is of course fluctuating, but around this value. Btw, this is when Eclipse is just running in the background, without even any java programs running in it. Is this normal memory usage by Eclipse?
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Jan 29, 2014
I am trying to write a specific byte sequence to a specific memory location on a removable storage drive. Does Java allow me a way to do this? I know the dangers in accessing memory, but the memory location of the data that will be written will never change.
how to assign a variable a memory location.
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Dec 7, 2014
Main screen leftsecond screen rightswing portal application is visible on two screens. If you open a context menu (right mouse) on the right screen, the context menu open on the left (Main) screen instead of the right.
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Apr 18, 2014
I'm doing a little game in Java and I would like to insert a background music managed by a JButton. When the button is pressed, the music starts and then, to stop it, the button is pressed again. If you don't press the button to stop the music remains in the loop until the player plays.
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Dec 11, 2013
I've forgotten the file location of the Java Console contents on a Windows XP system.
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Mar 30, 2015
I am new to Android. I have byte array of size 10. I am passing the Decimal values (131 - 140) to byte array. But while printing I get Negative (-) values with decreasing order .
How can I get same value as positive values?
Or How can I store positive value e.g. 131 as byte array element.
Please not my requirement is array must be ByteArray only
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Apr 27, 2015
I have a checksum function that is suppose to read IPV4 packet and return a short integer value. The IPV4 packets are stored in a byte array. I am having trouble storing the first 8 bits and second 8 bits of the short integer into the byte arrays especially when they have leading 1s. For example, if my checksum returns 5571 (binary = 0001 0101 1100 0011) The first 8 bits is suppose to represent 195 but when I try to assign a larger integer type to a btye the information gets sign extended. The 195 turns into -61. I tried using bit addition like array[10] = array[10] & 0xff, but the result remains the same.
public static short checksum(byte [] a, int length) {
short sum = 0;
long data;
int i = 0;
while(length > 1) {
data = (((a[i] << 8) & 0xff00) | ((a[i + 1]) & 0xff));
sum += data;
[code]....
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May 5, 2015
I have to build a simulated OS for my college class. I'm making it pretty simple, nothing too fancy and am using HTML5 Canvas. So far I have the icons on a black background and have made them draggable. I want to know how I can make it so when you click on an icon a box appears (just like a real OS) and then closes by clicking on the 'x'. I also want to be able to drag any icon into the trash bin and it disappears. I understand there are click/mouse events, but I don't know how to implement them into the code I have setup. Here's the code:
<!DOCTYPE HTML>
<html>
<head>
</head>
<body>
<div id="canvas"></div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/kineticjs/5.2.0/kinetic.js"></script>
<script defer="defer">
var stage = new Kinetic.Stage({
container: 'canvas',
width: 1910,
height: 995,
[Code] ....
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Jun 30, 2014
In this simple example, I print a byte array to String:
Java Code:
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
public class PrintByteArray {
public void print(){
System.out.println(Charset.defaultCharset());
byte[] arr = {1, 2, 3, 4};
[Code] ....
However, Eclipse prints out strange boxes, which I was unable to copy into this message.
It's supposed to print out the values of the bytes. What am I doing wrong?
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Mar 2, 2014
I am trying to write a byte array to a blob field in my database.
Below code is not working for me because the object is actually 902 bytes, however, the database tells me that it is 11 bytes once committed.
How to write to the blob field in my database?
Java Code:
protected void addFingerprint(byte[] fingerprintBytes) {
Statement stat;
try
{
updateQuery = "UPDATE " + currentTable + " SET CLERK_FINGERPRINT_DATA_BLOB = '"
[Code] ....
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Feb 20, 2014
I just wrote a small but working code to parse a multipart message with two files binary encoded.
Problem is, after splitting the content of the files is reduced to normal "alphabetic" digits, and i dont know why.
I just appended my source code and a test file ( multipart ). And the result of my parsing. (part_0 = json, part_1 = file, part_2 = file)
Unfortunately, i dont know, if the Spring FW provides an easier way of doing so at all. Haven't found it yet.
Java Code:
String requestUrl = "http://localhost:8888/";
RestTemplate restTemplate = new RestTemplate();
restTemplate.getMessageConverters().add(new ByteArrayHttpMessageConverter());
HttpEntity<String> entity = new HttpEntity<String>("test");
ResponseEntity<byte[]> response = restTemplate.exchange(requestUrl, HttpMethod.GET, entity, byte[].class);
[Code] .....
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Jul 12, 2014
I'm trying to save a picture from byte arrays using RandomAccessFile. The file appears but doesn't open (like its corrupted).
I'm using the bittorent protocol which gives a SHA-1 hash that I compare all the bytes with to verify the data. All the bytes pass the hash check and all the hashes are checked. So I'm pretty sure I'm getting all the bytes correctly.
Is there anything I can do that could tell what's going wrong?
public RUBTClient(final TorrentInfo2 tInfo, final String outFileName) {
...
this.outFileName = outFileName;
File destined = new File(outFileName);
try {
destined_file = new RandomAccessFile(destined, "rw");
destined_file.setLength(tInfo.file_length);
} catch (FileNotFoundException e1) {
[Code] .....
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Oct 3, 2014
So I have that traditional memory game homework assignment and for some reason I can't figure out how to put the codes in order. I can't figure out the arrangement to make it work. So far I have
import java.util.Random;
import java.util.Scanner;
public class MemoryGame {
[Code].....
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Mar 15, 2015
okay so it says that java int short and byte variables are the same thing. They take whole numbers. But what is the point of byte and short to even exist if int covers it all? Is the short and byte just for fun?
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Jun 5, 2014
I use git as my SCM and I use both Ubuntu and Mac OSX. The home directory of the two operating systems are different and there lies the problem. When I commit the .classpath to version control, it looks something like this:
Java Code:
<classpath>
<classpathentry kind="src" path="src"/>
<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER"/>
<classpathentry kind="lib" path="/Users/MyUser/Documents/github/Gateway/GDGateway/java-json.jar"/>
<classpathentry kind="lib" path="/Users/MyUser/Documents/github/Gateway/GDGateway/postgresql-9.3-1101.jdbc41.jar"/>
<classpathentry kind="output" path="bin"/>
</classpath> mh_sh_highlight_all('java');
Now when I update my project on Ubuntu. I have to change the build path again because it is referencing paths on OSX. And this goes back and forth. Rather than remove this file from git with .gitignore, I'd prefer to use a global environment variable like as follows:
Java Code:
<classpath>
<classpathentry kind="src" path="src"/>
<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER"/>
<classpathentry kind="lib" path="$HOME/Documents/github/Gateway/GDGateway/java-json.jar"/>
<classpathentry kind="lib" path="$HOME/Documents/github/Gateway/GDGateway/postgresql-9.3-1101.jdbc41.jar"/>
<classpathentry kind="output" path="bin"/>
</classpath> mh_sh_highlight_all('java');
Is this possible?
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May 19, 2015
While loading very huge xml file i m getting heap space error in myeclipse. So I wanted how to increase memory so that xml file will get loaded?
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Oct 14, 2014
I've a small question relating to type promotion I can't find an answer for on the web. Basically in your code if you have :
byte b = 0;
b = b + 1;
The compiler will complain about the result being an int which cannot be assigned to a byte. That I understand, as b on the right hand side of the expression is promoted to an int and the result of the addition is an int. However the following does compile :
byte b = 0;
b++;
Does the post increment not carry out the post increment as "give me the value of b and then add 1 to b" where I would have expected 'add 1 to b' to do the same integer promotion as the previous example ? The compiler will also allow the following
byte b = 0;
b += 1;
Again , why is no type promotion happening here ?
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Apr 22, 2014
I am creating a web application that runs on server X(unix) and it has another unix system mounted on it. I want to generate the file tree structure of this mounted unix file system and show it on to a web application so that users can select a file and move it onto this current unix machine.
I know this sounds stupid and you may want to say why cant we directly copy the file, I am doing a proof of concept and using this as a basis.
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Jan 10, 2015
I need to make some operations with a file. I struggle to understand why Apache is throwing this error:
(The system cannot find the file specified)
My file is located in the root directory of the project.
And here is how I indicate the path to it:
String filePath = "default.jpg";
InputStream inputStream = new FileInputStream(new File(filePath));
If I put the file in the Eclipse folder, it works... But I need it to work if I put it in my project's root folder.
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Mar 9, 2015
I am new to java and I am creating a system that will ask the user to create a file that will store to a text file, Once the user created the file I have a class that will let the user input the subject name that has been created, However, I keep on getting this java.util.nosuchelementexception.Here's my code:
public void display_by_name()
{
String id, name,total;
String key[]=new String[30];
String value[]=new String[30];
int i=0;
[code]....
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Feb 13, 2015
"A common memory matching game played by young children is to start with a deck of cards that contain identical pairs. For example, given six cards in the deck, two might be labeled
1, two might be labeled
2 and two might be labeled
3. The cards are shuffled and placed face down on the table.
The player then selects two cards that are face down, turns them face up, and if they match they are left face up. If the two cards do not match they are returned to their original position face down. The game continues in this fashion until all cards are face up.Write a program that plays the memory matching game. Use sixteen cards that are laid out in a 4x4 square and are labeled with pairs of numbers from 1 to 8. Your program should allow the player to specify the cards that she would like to select through a coordinate system.For example in the following layout:
1 2 3 4
--------------------
1 | 8 * * *
2 | * * * *
3 | * 8 * *
4 | * * * *
All of the cards are face down except for the pair 8 which has been located at coordinates (1,1) and (2,3). To hide the cards that have been temporarily placed face up, output a large number of newlines to force the old board off the screen.Use 2D array for the arrangement of cards and another 2D array that indicates if a card is face up or face down.Or, a more elegant solution is to create a single 2D array where each element is an object that stores both the cards value and face.Write a function that shuffles the cards in the array by repeatedly selecting two cards at random and swapping them.
Note:To generate a random number x, where 0<= x <1, use x=Math.random();.For example, multiplying y six and converting to an integer results in an integer that is from 0 to 5."I have been thinking about the algorithm and design of the question for a few hours.
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Jun 13, 2013
I searched everywhere but i didn't found anything about the real size of primitive boolean type used by java.
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Jul 18, 2014
Creating an array searcher wherein it all depends on the user input. On the first user input it would be the array to search from while the second input would be something to be searched for inside the loop?
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Aug 29, 2014
I would like to know how much of memory is free and used my java program.I have used Runtime.totalMemory and freeMemory() functions. However, how come used memory is so different than java.exe process show in windows task manager?
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