I want to sort anarray by the object type. So all songs are together, all book are together, and all movies are together.
I am reading a file and determine what each object should be. then creating the object and adding it to the array.
EDIT: Here is the actual code.
static Media[] ReadData()
{
List<Media> things = new List<Media>();
try
{
String filePath = "resources/Data.txt";
string Line;
int counter = 0; // used to check if you have reached the max
number of allowed objects (100)
using (StreamReader File = new System.IO.StreamReader(filePath))
{
while ((Line = File.ReadLine()) != null)
{
This is where each object is created. The file
search for a key word in the beginning of the line, then
creates the corresponding object. It will split the
information on the first line of the object and will
read each line until a "-" character is found and
pass each line into the summary. The summary is then
decrypted and the created object is passed into an
array List. Finally if the array list reaches 100, it
will print "You have reach max number of objects" and
stop reading the file.
if (Line.StartsWith("BOOK"))
{
String[] tempArray = Line.Split('|');
//foreach (string x in tempArray){Console.WriteLine(x);} //This is used
for testing
Book tempBook = new Book(tempArray[1],
int.Parse(tempArray[2]), tempArray[3]);
while ((Line = File.ReadLine()) != null)
{
if (Line.StartsWith("-")){break;}
tempBook.Summary = tempBook.Summary + Line;
}
tempBook.Summary = tempBook.Decrypt();
things.Add(tempBook);
counter++;
}
else if (Line.StartsWith("SONG"))
{
String[] tempArray = Line.Split('|');
//foreach (string x in tempArray)
{Console.WriteLine(x);} //This is used for testing
Song tempSong = new Song(tempArray[1],
int.Parse(tempArray[2]), tempArray[3], tempArray[4]);
things.Add(tempSong);
counter++;
}
else if (Line.StartsWith("MOVIE"))
{
String[] tempArray = Line.Split('|');
//foreach (string x in tempArray)
{Console.WriteLine(x);} //This is used for testing
Movie tempMovie = new Movie(tempArray[1],
int.Parse(tempArray[2]), tempArray[3]);
while ((Line = File.ReadLine()) != null)
{
if (Line.StartsWith("-")) { break; }
tempMovie.Summary = tempMovie.Summary + Line;
}
tempMovie.Summary = tempMovie.Decrypt();
things.Add(tempMovie);
counter++;
}
if (counter == 100)
{
Console.WriteLine("You have reached the maximum number of media
objects.");
break;
}
}
File.Close();
}
}
return things.ToArray(); // Convert array list to an Array and return the
array.
}
In the main code, I have this:
Media[] mediaObjects = new Media[100];
Media[] temp = ReadData();
int input; // holds the input from a user to determin which action to take
for (int i = 0; i<temp.Length;i++){ mediaObjects[i] = temp[i]; }
I want the array of mediaObjects to be sorted by the what type of objects.
I have also used Icomparable to do an arrayList.sort() but still no luck.
public int CompareTo(object obj)
{
if (obj == null)
{
return 1;
}
Song temp = obj as Song;
if (temp != null)
{
//Type is a string
return this.Type.CompareTo(temp.Type);
}
else
{
return 1;
}
}
So I see you have BOOK, SONG and MOVIE types.
This is a classic case of implementing the IComparable interface - although you are correct with the interface name to implement, you are not using this correctly.
Create a base class by the name MediaObject - this will be the main one for your other types of objects you create.
Add the correct properties you need. In this case, the media type is the one in need.
Let this class implement IComparable to help you with the comparison.
override the CompareTo() method in the PROPER way
public class MediaObject : IComparable
{
private string mediaType;
public string MediaType
{
get {return mediaType;}
set {mediaType=value;}
}
public MediaObject(string mType)
{
MediaType = mType;
}
int IComparable.CompareTo(object obj)
{
MediaObject mo = (MediaObject)obj;
return String.Compare(this.MediaType,mo.MediaType); //implement a case insensitive comparison if needed (for your research)
}
}
You can now compare the MediaObject objects In your main method directly.
Thank for the advice. I ended up just reformating how I was creating the list while reading it. I made multiple lists for each object then just happened each one on to the master list so It showed up sorted. I wish I figured that out before I made this long post.
As far as I could find, you can't sort by the type of object in a generic array. If anyone has a better solution feel free to post it.
Am trying to show someone over here how good I find the sonar
tool...
then I wrote a small java project and defined many intentionally smelly methods,
2 of those are exactly the same (copy+paste) do1 and do2
surprisenly, after running the sonnar, there is no duplication error nor warnings...
public void do1() {
for (int i = 0; i < 10; i++) {
if (i != 0) {
System.out.println("Hello");
System.out.println(new Date());
}
}
}
public void do2() {
for (int i = 0; i < 10; i++) {
if (i != 0) {
System.out.println(new Date());
System.out.println("Hello");
}
}
}
what is the criteria for a java project to raise a warning on duplicates then?
Your methods are too short to show up as duplicated. Per the docs,
There should be at least 10 successive and duplicated statements whatever the number of tokens and lines.
I need to write a program that records the frames, but only when one skeleton/body is in the frame. I looked at the bodyCount method, but it always gives a value of 6 (useless). One thing I tried to do is shown below. This code basically shows the index at which the body being tracked is stored. But, I still can't figure out how to know if there is one or more bodies in the frame.
I would really appreciate any help.
Thanks in advance.
private void Reader_FrameArrived(object sender, BodyFrameArrivedEventArgs e){
using (BodyFrame bodyFrame=e.FrameReference.AquireFrame()){
if (bodyFrame!=null){
if(this.bodies==null){
this.bodies=new Body[bodyFrame.BodyCount];
}
body.Frame.GetAndRefreshBodyData(this.bodies)
for(int i=0; i<6;i++){
if(this.bodies[i].IsTracked){
Console.WriteLine("Tracked"+i)
}
}
}
}
}
Just check the IsTracked property of each body, and store the number of tracked skeleton in a single variable. If this number is equal to 1, there is just one single skeleton tracked, and you can start your recording.
private Body[] bodies = null;
[...]
private void Reader_FrameArrived(object sender, BodyFrameArrivedEventArgs e)
{
bool dataReceived = false;
using (BodyFrame bodyFrame = e.FrameReference.AcquireFrame())
{
if (bodyFrame != null)
{
if (this.bodies == null)
{
this.bodies = new Body[bodyFrame.BodyCount];
}
// The first time GetAndRefreshBodyData is called, Kinect will allocate each Body in the array.
// As long as those body objects are not disposed and not set to null in the array,
// those body objects will be re-used.
bodyFrame.GetAndRefreshBodyData(this.bodies);
dataReceived = true;
}
}
if (dataReceived)
{
int trackedBodyCount = 0;
for (int i=0; i<this.bodies.Length; ++i)
{
if(this.bodies[i].IsTracked) {
trackedBodyCount += 1;
}
}
if (trackedBodyCount == 1)
{
// One skeleton is tracked
}
}
}
I'm using a custom AVIOContext to bridge FFMpeg with java IO. The function avformat_open_input() never returns. I have searched the web for similar problems, all of which were caused by faulty network or wrong server configurations. However, I'm not using network at all, as you can see in the following little program:
package com.example;
import org.bytedeco.javacpp.*;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import static org.bytedeco.javacpp.avcodec.*;
import static org.bytedeco.javacpp.avformat.*;
import static org.bytedeco.javacpp.avutil.*;
import static org.bytedeco.javacpp.avdevice.*;
import static org.bytedeco.javacpp.avformat.AVFormatContext.*;
public class Test {
public static void main(String[] args) throws Exception {
File dir = new File(System.getProperty("user.home"), "Desktop");
File file = new File(dir, "sample.3gp");
final RandomAccessFile raf = new RandomAccessFile(file, "r");
Loader.load(avcodec.class);
Loader.load(avformat.class);
Loader.load(avutil.class);
Loader.load(avdevice.class);
Loader.load(swscale.class);
Loader.load(swresample.class);
avcodec_register_all();
av_register_all();
avformat_network_init();
avdevice_register_all();
Read_packet_Pointer_BytePointer_int reader = new Read_packet_Pointer_BytePointer_int() {
#Override
public int call(Pointer pointer, BytePointer buf, int bufSize) {
try {
byte[] data = new byte[bufSize]; // this is inefficient, just use as a quick example
int read = raf.read(data);
if (read <= 0) {
System.out.println("EOF found.");
return AVERROR_EOF;
}
System.out.println("Successfully read " + read + " bytes of data.");
buf.position(0);
buf.put(data, 0, read);
return read;
} catch (Exception ex) {
ex.printStackTrace();
return -1;
}
}
};
Seek_Pointer_long_int seeker = new Seek_Pointer_long_int() {
#Override
public long call(Pointer pointer, long offset, int whence) {
try {
raf.seek(offset);
System.out.println("Successfully seeked to position " + offset + ".");
return offset;
} catch (IOException ex) {
return -1;
}
}
};
int inputBufferSize = 32768;
BytePointer inputBuffer = new BytePointer(av_malloc(inputBufferSize));
AVIOContext ioContext = avio_alloc_context(inputBuffer, inputBufferSize, 1, null, reader, null, seeker);
AVInputFormat format = av_find_input_format("3gp");
AVFormatContext formatContext = avformat_alloc_context();
formatContext.iformat(format);
formatContext.flags(formatContext.flags() | AVFMT_FLAG_CUSTOM_IO);
formatContext.pb(ioContext);
// This never returns. And I can never get result.
int result = avformat_open_input(formatContext, "", format, null);
// all clean-up code omitted for simplicity
}
}
And below is my sample console output:
Successfully read 32768 bytes of data.
Successfully read 32768 bytes of data.
Successfully read 32768 bytes of data.
Successfully read 32768 bytes of data.
Successfully read 32768 bytes of data.
Successfully read 7240 bytes of data.
EOF found.
I've checked the sum of bytes, which corresponds to the file size; EOF is also hit, meaning the file is completely read. Actually I am a bit skeptical as why avformat_open_input() would even read the entire file and still without returning? There must be something wrong with what I am doing. Can any expert shed some lights or point me to the right direction? I'm new to javacv and ffmpeg and especially to programming with Buffers and stuff. Any help, suggestion or criticism is welcome. Thanks in advance.
Ok, now I have found the problem. I have misinterpreted the docs and overlooked most of the examples I found. My bad.
According to the documentation on ffmpeg:
AVIOContext* avio_alloc_context (unsigned char* buffer,
int buffer_size,
int write_flag,
void* opaque,
int(*)(void *opaque, uint8_t *buf, int buf_size) read_packet,
int(*)(void *opaque, uint8_t *buf, int buf_size) write_packet,
int64_t(*)(void *opaque, int64_t offset, int whence) seek
)
The third parameter, write_flag is used in the following fashion:
write_flag - Set to 1 if the buffer should be writable, 0 otherwise.
Actually, it means if the AVIOContext is for data output (i.e. writing), write_flag should be set to 1. Otherwise, if the context is for data input (i.e. reading), it should be set to 0.
In the question I posted, I passed 1 as the write_flag and it is causing the problem when reading. Passing 0 instead solves the problem.
Later I re-read all the examples I found, all the avio_alloc_context() calls uses 0, not 1 when reading. So that further indicates why I'm having the problem.
To conclude, I will post the revised code with the problems corrected as a future reference.
package com.example;
import org.bytedeco.javacpp.*;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import static org.bytedeco.javacpp.avformat.*;
import static org.bytedeco.javacpp.avutil.*;
import static org.bytedeco.javacpp.avformat.AVFormatContext.*;
public class Test {
public static void main(String[] args) throws Exception {
File dir = new File(System.getProperty("user.home"), "Desktop");
File file = new File(dir, "sample.3gp");
final RandomAccessFile raf = new RandomAccessFile(file, "r");
Loader.load(avformat.class);
Loader.load(avutil.class);
av_register_all();
avformat_network_init();
Read_packet_Pointer_BytePointer_int reader = new Read_packet_Pointer_BytePointer_int() {
#Override
public int call(Pointer pointer, BytePointer buf, int bufSize) {
try {
byte[] data = new byte[bufSize]; // this is inefficient, just use as a quick example
int read = raf.read(data);
if (read <= 0) {
// I am still unsure as to return '0', '-1' or 'AVERROR_EOF'.
// But according to the following link, it should return 'AVERROR_EOF',
// http://www.codeproject.com/Tips/489450/Creating-Custom-FFmpeg-IO-Context
// btw 'AVERROR_EOF' is a nasty negative number, '-541478725'.
return AVERROR_EOF;
}
buf.position(0);
buf.put(data, 0, read);
return read;
} catch (Exception ex) {
ex.printStackTrace();
return -1;
}
}
};
Seek_Pointer_long_int seeker = new Seek_Pointer_long_int() {
#Override
public long call(Pointer pointer, long offset, int whence) {
try {
if (whence == AVSEEK_SIZE) {
// Returns the entire file length. If not supported, simply returns a negative number.
// https://www.ffmpeg.org/doxygen/trunk/avio_8h.html#a427ff2a881637b47ee7d7f9e368be63f
return raf.length();
}
raf.seek(offset);
return offset;
} catch (IOException ex) {
ex.printStackTrace();
return -1;
}
}
};
int inputBufferSize = 32768;
BytePointer inputBuffer = new BytePointer(av_malloc(inputBufferSize));
AVIOContext ioContext = avio_alloc_context(inputBuffer,
inputBufferSize,
0, // CRITICAL, if the context is for reading, it should be ZERO
// if the context is for writing, then it is ONE
null,
reader,
null,
seeker);
AVInputFormat format = av_find_input_format("3gp");
AVFormatContext formatContext = avformat_alloc_context();
formatContext.iformat(format);
formatContext.flags(formatContext.flags() | AVFMT_FLAG_CUSTOM_IO);
formatContext.pb(ioContext);
// Now this is working properly.
int result = avformat_open_input(formatContext, "", format, null);
System.out.println("result == " + result);
// all clean-up code omitted for simplicity
}
}
References:
AVSEEK_SIZE documentation
avio_alloc_context() documentation
Additional References: (I do not have enough reputation points for more links but I found these examples critical in helping me so I pasted them in plain text anyway)
Creating Custom FFmpeg IO-Context (CodeProject Example) at:
http://www.codeproject.com/Tips/489450/Creating-Custom-FFmpeg-IO-Context
Another example showing the use of write_flag in avio_alloc_context() at:
https://www.ffmpeg.org/doxygen/2.5/avio_reading_8c-example.html#a20
Your seek code needs to handle AVSEEK_SIZE as whence, and your read should return 0 on EOF ("Upon reading end-of-file, zero is returned." - literal quote from man 2 read), not AVERROR_EOF.
IBM (see Source) wrote on the benefits of Java's 1.5 java.util.concurrent class, which offers non-blocking queues.
Please explain the weaknesses/disadvantages of the NonBlockingCounter below.
public class NonblockingCounter {
private AtomicInteger value;
public int getValue() {
return value.get();
}
public int increment() {
int v;
do {
v = value.get();
}
while (!value.compareAndSet(v, v + 1)); // params - (actual, expected)
return v + 1;
}
}
Source - http://www.ibm.com/developerworks/java/library/j-jtp04186/index.html
The disadvantage is that it spins while trying to increment the value if there's contention. That means it's bad for high-contention locks.
The advantage is that it doesn't have lock acquistion/semaphore overhead. That's good for low-contention locks.