Going from an array of integer pixels to a saved image (JPEG etc)

I'm sure someone who knows the APIs better than me can answer this:
I have written a scanner interface (in JNI) which ends up giving me an array of pixels. I can easily turn this array of pixels into an Image like this:
MemoryImageSource mis = new MemoryImageSource(width, height, imageData, offset, width);
Toolkit kit = Toolkit.getDefaultToolkit();
Image image = kit.createImage(mis);But then it's fairly difficult to save that Image as a file. The easy way to save images is to use ImageIO.write(RenderedImage ...). But the problem is that Image does not implemented RenderedImage. Is there a simple (high-performance) solution to this? I'm sure there is a straightforward way to do it, somewhere within the API.
Thanks

I figured out a solution that seems to work well:
I create a blank BufferedImage and then I simply use bufferedImage.setRGB(...), much like using MemoryImageSource. Then I can use ImageIO to save the buffered image in any format I want, no problem.
Ah, the world of Java imaging is so confusing.

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I believe the default is for them to order themselves in 'date taken' order. Unfortunately there's nothing you can do to change that. It's the default in the photos app and users can't change it. You can try looking for a third party photo app that may have more functionality. Afraid I can't recommend any since I've never looked for them but I'm sure someone can.

Only writing Integer pixel array to a .txt file,or showing in Frame

Sir,
I want to write integer values (range:0 to 255) to a .txt file .Actually after manipulating a .jpeg/.gif image I have gotten a 2D pixel array and a 1D pixel array that can be easily shown in console but I want to write this pixel array into a .txt file. Using of writeInt() is not working. Actually after using this faction the created file contain information which is non-alphanumeric /alphanumeric characters......
following is error free the code: Plz. See only and only into the �class TestImage�and plz look after line marked by //�my_problem_to_be_resolved.�It is just few lines of code .I promise you will not be bothered.Plz��..
import java.awt.*;
import java.io.File;
import java.io.FileWriter;
import java.awt.image.*;
import java.io.*;
import java.util.*;
import javax.imageio.*;
import javax.imageio.stream.*;
import java.awt.image.Raster;
import java.awt.image.WritableRaster;
class Image {
protected int width,height;
// 'samples' stores the image pixel values.
protected int[][] samples;
// Constructor: Reads the image from the
// specified file name.
public Image(String filename)
throws Exception { read(filename); }
// Returns the pixel width of the image.
public int getWidth() { return width; }
// Returns the pixel height of the image.
public int getHeight() { return height; }
// Reads the image from the specified file
// name into the 'samples' array. Throws an
// exception if the image is stored in an
// unsupported file format (currently only
// .GIF, .JPG, and .PNG are supported by Sun).
public void read(String filename)
throws Exception {
// Extract the file name suffix.
String ext = filename.substring
(filename.indexOf('.')+1);
// Create a file object for the file name.
File fileImage = new File(filename);
// Get a list of ImageReaders that claim
// to be able to decode this image file
// based on the file name suffix.
Iterator imageReaders = ImageIO.
getImageReadersBySuffix(ext);
ImageReader imageReader;
// Grab the first ImageReader in the list.
if (imageReaders.hasNext())
imageReader = (ImageReader)
imageReaders.next();
// If we get here we cannot decode the image.
else throw new IIOException
("Unsupported image format");
// Create a file input stream object to
// read the image date.
FileImageInputStream imageInputStream =
new FileImageInputStream(fileImage);
// Tell the ImageReader object to read data
// from our file input stream object.
imageReader.setInput(imageInputStream);
// Get the width and height of the image.
width = imageReader.getWidth(0);
height = imageReader.getHeight(0);
// Read the image from the file input stream,
// and close the input stream when done.
BufferedImage bufImage =
imageReader.read(0);
imageInputStream.close();
// Get a raster object so we can extract the
// pixel data from the BufferedImage.
WritableRaster wRaster =
bufImage.getRaster();
// Create our 'samples' 2d-array.
samples = new int[height][width];
// Extract the image data into our 'samples'
// array.
for (int row = 0; row < height; row++)
for (int col = 0; col < width; col++)
samples[row][col] =
wRaster.getSample(col,row,0);
// Write the image stored in the 'samples'
// array to the specified file. The file name
// suffix should be a supported image file
// format (currently either .JPG or .PNG).
public void write(String filename)
throws Exception {
// Extract the file name suffix.
String ext = filename.substring
(filename.indexOf('.')+1);
// Create a file object for the file name.
File fileImage = new File(filename);
// Get a list of ImageWriters that claim to
// be able to encode images in the specified
// image file format based on the file name
// suffix.
Iterator imageWriters = ImageIO.
getImageWritersBySuffix(ext);
ImageWriter imageWriter;
// Grab the first ImageWriter in the list.
if (imageWriters.hasNext())
imageWriter = (ImageWriter)
imageWriters.next();
// If we get here we cannot encode the image.
else throw new IIOException
("Unsupported image format");
// Create a file output stream object to
// write the image data.
FileImageOutputStream imageOutputStream
= new FileImageOutputStream
(fileImage);
// Tell the ImageWriter to use our file
// output stream object.
imageWriter.setOutput
(imageOutputStream);
// The ImageWriter.write() method expects a
// BufferedImage. Convert our 'samples' array
// into a BufferedImage.
BufferedImage bufImage =
createBufferedImage();
// Encode the image to the output file.
imageWriter.write(bufImage);
imageOutputStream.close();
// Draws the image stored in the 'samples'
// array on the specified graphics context.
public void draw(Graphics gc,int x,int y){
BufferedImage bufImage =
createBufferedImage();
gc.drawImage(bufImage,x,y,null);
// Converts the 'samples' array into a
// BufferedImage object. Students do not have
// to understand how this works.
private BufferedImage
createBufferedImage() {
// Create a monochrome BufferedImage object.
BufferedImage bufImage = new
BufferedImage(width,height,
BufferedImage.TYPE_BYTE_GRAY);
// Create a WriteableRaster object so we can
// put sample data into the BufferedImage
// object's raster.
WritableRaster wRaster =
bufImage.getRaster();
// Copy the 'samples' data into the
// BufferedImage object's raster.
for (int row = 0; row < height; row++)
for (int col = 0; col < width; col++)
wRaster.setSample
(col,row,0,samples[row][col]);
// Return the newly created BufferedImage.
return bufImage;
} // End of Class Image
class TestImage {
public static void main(String args[])
throws Exception {
// Create a frame to display the image.
Frame frame = new Frame("Test Image");
frame.setSize(1024,768);
frame.setVisible(true);
Graphics gc = frame.getGraphics();
try {
// Read the image from the file.
Image img = new Image("C:/lilies.jpg");
int height=img.getHeight();
int width =img.getWidth();
//�my_problem_to_be_resolved.�
     File image_object_arry=new File("C:/Image_array.txt");
     FileOutputStream image_object_arry_stream= new FileOutputStream(image_object_arry);
     DataOutputStream int_image_object_arry_stream=new DataOutputStream(image_object_arry_stream);
//Conversion of two dimensional pixel arrry into one dimensional array
int intPixels1[] = new int [height * width];
int k = 0;
for(int i = 0; i <= width; i++) {
for(int j = 0; j <= height; j++) {
intPixels1[k] = img.samples[i][j];
int_image_object_arry_stream.writeInt((int) intPixels1[k]);
// System.out.println(intPixels1[k]);
k = k+1;
import java.awt.*;
import java.io.File;
import java.io.FileWriter;
import java.awt.image.*;
import java.io.*;
import java.util.*;
import javax.imageio.*;
import javax.imageio.stream.*;
import java.awt.image.Raster;
import java.awt.image.WritableRaster;
class Image {
protected int width,height;
// 'samples' stores the image pixel values.
protected int[][] samples;
// Constructor: Reads the image from the
// specified file name.
public Image(String filename)
throws Exception { read(filename); }
// Returns the pixel width of the image.
public int getWidth() { return width; }
// Returns the pixel height of the image.
public int getHeight() { return height; }
// Reads the image from the specified file
// name into the 'samples' array. Throws an
// exception if the image is stored in an
// unsupported file format (currently only
// .GIF, .JPG, and .PNG are supported by Sun).
public void read(String filename)
throws Exception {
// Extract the file name suffix.
String ext = filename.substring
(filename.indexOf('.')+1);
// Create a file object for the file name.
File fileImage = new File(filename);
// Get a list of ImageReaders that claim
// to be able to decode this image file
// based on the file name suffix.
Iterator imageReaders = ImageIO.
getImageReadersBySuffix(ext);
ImageReader imageReader;
// Grab the first ImageReader in the list.
if (imageReaders.hasNext())
imageReader = (ImageReader)
imageReaders.next();
// If we get here we cannot decode the image.
else throw new IIOException
("Unsupported image format");
// Create a file input stream object to
// read the image date.
FileImageInputStream imageInputStream =
new FileImageInputStream(fileImage);
// Tell the ImageReader object to read data
// from our file input stream object.
imageReader.setInput(imageInputStream);
// Get the width and height of the image.
width = imageReader.getWidth(0);
height = imageReader.getHeight(0);
// Read the image from the file input stream,
// and close the input stream when done.
BufferedImage bufImage =
imageReader.read(0);
imageInputStream.close();
// Get a raster object so we can extract the
// pixel data from the BufferedImage.
WritableRaster wRaster =
bufImage.getRaster();
// Create our 'samples' 2d-array.
samples = new int[height][width];
// Extract the image data into our 'samples'
// array.
for (int row = 0; row < height; row++)
for (int col = 0; col < width; col++)
samples[row][col] =
wRaster.getSample(col,row,0);
// Write the image stored in the 'samples'
// array to the specified file. The file name
// suffix should be a supported image file
// format (currently either .JPG or .PNG).
public void write(String filename)
throws Exception {
// Extract the file name suffix.
String ext = filename.substring
(filename.indexOf('.')+1);
// Create a file object for the file name.
File fileImage = new File(filename);
// Get a list of ImageWriters that claim to
// be able to encode images in the specified
// image file format based on the file name
// suffix.
Iterator imageWriters = ImageIO.
getImageWritersBySuffix(ext);
ImageWriter imageWriter;
// Grab the first ImageWriter in the list.
if (imageWriters.hasNext())
imageWriter = (ImageWriter)
imageWriters.next();
// If we get here we cannot encode the image.
else throw new IIOException
("Unsupported image format");
// Create a file output stream object to
// write the image data.
FileImageOutputStream imageOutputStream
= new FileImageOutputStream
(fileImage);
// Tell the ImageWriter to use our file
// output stream object.
imageWriter.setOutput
(imageOutputStream);
// The ImageWriter.write() method expects a
// BufferedImage. Convert our 'samples' array
// into a BufferedImage.
BufferedImage bufImage =
createBufferedImage();
// Encode the image to the output file.
imageWriter.write(bufImage);
imageOutputStream.close();
// Draws the image stored in the 'samples'
// array on the specified graphics context.
public void draw(Graphics gc,int x,int y){
BufferedImage bufImage =
createBufferedImage();
gc.drawImage(bufImage,x,y,null);
// Converts the 'samples' array into a
// BufferedImage object. Students do not have
// to understand how this works.
private BufferedImage
createBufferedImage() {
// Create a monochrome BufferedImage object.
BufferedImage bufImage = new
BufferedImage(width,height,
BufferedImage.TYPE_BYTE_GRAY);
// Create a WriteableRaster object so we can
// put sample data into the BufferedImage
// object's raster.
WritableRaster wRaster =
bufImage.getRaster();
// Copy the 'samples' data into the
// BufferedImage object's raster.
for (int row = 0; row < height; row++)
for (int col = 0; col < width; col++)
wRaster.setSample
(col,row,0,samples[row][col]);
// Return the newly created BufferedImage.
return bufImage;
} // End of Class Image
/*class TestImage {
public static void main(String args[])
throws Exception {
// Create a frame to display the image.
Frame frame = new Frame("Test Image");
frame.setSize(1024,768);
frame.setVisible(true);
Graphics gc = frame.getGraphics();
try {
// Read the image from the file.
Image img = new Image("C:/srk.jpg");
// Display the image.
img.draw(gc,10,40);
// Flip the image upside down
//img.flipX();
// Display the flipped image.
img.draw(gc,20+img.getWidth(),40);
// Write the new image to a file
img.write("HorseNew.jpg");
} catch (Exception e) {
System.out.println
("Exception in main() "+e.toString());
class TestImage {
public static void main(String args[])
throws Exception {
// Create a frame to display the image.
Frame frame = new Frame("Test Image");
frame.setSize(1024,768);
frame.setVisible(true);
Graphics gc = frame.getGraphics();
try {
// Read the image from the file.
Image img = new Image("C:/lilies.jpg");
int height=img.getHeight();
int width =img.getWidth();
File image_object_arry=new File("C:/Image_array.txt");
FileOutputStream image_object_arry_stream=new FileOutputStream(image_object_arry);
     DataOutputStream int_image_object_arry_stream=new DataOutputStream(image_object_arry_stream);
//Conversion of two dimensional pixel arrry into one dimensional array
int intPixels1[] = new int [height * width];
int k = 0;
for(int i = 0; i <= width; i++) {
for(int j = 0; j <= height; j++) {
intPixels1[k] = img.samples[i][j];
int_image_object_arry_stream.writeInt((int) intPixels1[k]);
// System.out.println(intPixels1[k]);
k = k+1;
catch (Exception e) {
System.out.println("Exception in main() "+e.toString());
catch (Exception e) {
System.out.println("Exception in main() "+e.toString());
}

My Friend, you need to put your code within CODE tags
And I suspect if anyone would go through your code this way.
Assuming your problem is to write pixel values to a file you may use this,
      try{
        // Create file
        FileWriter fstream = new FileWriter("out.txt");
        BufferedWriter out = new BufferedWriter(fstream);
        for(int i =0; pixels.length() ; i++)
          out.write(pixels[i]+"\t");
       //Close the output stream
       out.close();
       }catch (Exception e){//Catch exception if any
      System.err.println("Error: " + e.getMessage());
    }

Displaying a picture from an array of pixel values

I have a picture I want to display in an AWT frame. The picture is stored as several arrays of pixel values which represent rectangles.
Each rectangle has a start co-ordinate and a height and width.
There is a ColorModel associated with the pixel values, so that's not a problem.
What's the best way to display these rectangles as pixels, and patch them all together to make the full picture? I'm currently trying to use a MemoryImageSource, but I'm having trouble displaying more than one rectangle at once, and the picture flickers like mad, suggesting MemoryImageSource intended for animation, whereas I just want to display the picture once.
Any suggestions?

OK, that looks good. I'm investigating it.
However, It's not clear how to get the pixel values from an array into it. It requires a WriteableRaster of the pixel data, and to create a WriteableRaster, you need a DataBuffer... which is Abstract!
Do you know how to make a DataBuffer from an array?

Create an image from float array?

Dear All,
I have a float array containing pixel values. From that array I want to create an image (let's say in JPEG format).
How should I do that?
thanks

Hi musti168,
You're going through your entire image pixel-by-pixel and getting each of their values - why don't you just use the IMAQ ImageToArray function?
On this forum post I found an example of IMAQ ArrayToImage: http://forums.ni.com/t5/LabVIEW/IMAQ-arraytoimage-example/td-p/68418
You can use some of the IMAQ Image Processing palette to change the image to gray scale - possibly a threshold.
Julian R.
Applications Engineer
National Instruments

How to delete a random set of indizes from an array as fast as possible?

Hello,
My question sounds a bit like this thread but it isn't... :-(
http://forums.ni.com/ni/board/message?board.id=170&message.id=129888&query.id=10689#M129888
When sampling position/force/resistance data I use a time triggered sampling approach. For later analysis I need (among others) force (Y) over position (x).
To get this I calculate the mean force from all time points with equal positions (as time is my common index). That works quite well but with arrays over 300000 points it becomes a bit too slow...
These are my steps so far:
1. Sort the position array
2. Eliminate duplicates from the position array (no array reshape in loop)
3. With the data from 2. get all indices where my original position array has a given value
4. With the indices from 3. get the corresponding force values from the force raw data and calculate the mean
In step 3 I need to search the whole raw position array as many times as there are different position values in itself.
If I could delete all indizes I already found from the array to search that should (in theory) significantly improve performance. On the other hand such an operation would mean a lot of array reshape operations.
What is the best approach to delete the found indizes?
OR
Is there no benefit in deleting the indizes as the array operations to do this need more time than they save?
Thanks!
Sören

Now I'm getting a bit more confused about the app. If you need a sampling rate higher than the encoder can provide, then then only way I can think of to accumulate multiple readings at the same position is if you have some type of bi-directional cyclical motion. But if you originally used the encoder as a sampling clock, that seems to imply a unidirectional motion. Is the motion cyclical or unidirectional?
Knowing that I need to do some similar processing down the road, I did a bit of tinkering today. The method I described earlier took ~350 msec to process (sort and then calculate averages force per unique position) on 350,000 data points. A little more tinkering gave me a method that took <100 msec. The machine was a pretty new test PC with a 2.8 GHz Pentium. Here's an outline and perhaps I'll be able to scrub the code a bit to post soon. Hopefully someone will have some even better ideas!
The basic idea is essentially a histogram where each possible integer position value maps to a histogram bin.
1. Based on knowledge of your test equipment, you can know the # of unique positions that can possibly be recorded. Pre-initialize 2 arrays of this size before starting the main data acquisition. Both should be full of floating-point 0's. These will hold (a) count of entries and (b) sum of forces. Call them the binning arrays. My test used a size of 8000 possible positions.
2. An auto-indexing For loop goes through the 350,000 integer positions and floating point forces. The binning arrays enter this loop through shift registers.
3. For each pair, use the integer position to map yourself to the appropriate index of the binning arrays. Increment that element of the count array and add this iteration's force value to the sum array.
4. After loop completes, divide sum array by count array. These are your average forces. (This is why the count is computed as a floating point value. It was very costly to allow a type coercion from an integer count array into the division function.) Note that unsampled positions should have 0 counts and produce a NaN result from the division.
There are also ways to calculate a running average in the loop, but I haven't checked (yet) to see if it's faster. The median you mentioned would need some extra post-loop steps.
I'm sure that if this were a coding challenge, someone would cut the processing time at least in half... Anyone out there?
-Kevin P.

Without loops how can i read data from associative Array??

Hi all,
I am facing scenario like...
i need to read data from associative array without using loops is it possible,
CREATE OR REPLACE PACKAGE BODY test_pkg IS
    TYPE t1 IS TABLE OF NUMBER INDEX BY BINARY_INTEGER;
   -- in array we can expect more than one row or sometimes no data also.
FUNCTION test1(vt1 T1 DEFAULT CAST(NULL AS t1)) RETURN NUMBER IS
BEGIN
    -- basically in array we'll get data of column2
    -- this loop should satisfies table1.colum2 = nvl(NULL, table2.colum2 )if array is null.
    -- if array is not null then only compare with array values
    FOR i IN (SELECT t1.colum1,t1.column2
                     FROM table1 t1, table1 t2
                          WHERE t1.colum1 = t2.column1
                            AND t1.colum2 = nvl(vt1, t2.colum2)
      LOOP
        generateTEXT(i.colum1, i.colum2);
     END LOOP;
END test1;
END test_pkg;
in table1 we have date like...
colum1          column2
Jan                  1
Feb                  2
Mar                  3
if i call select test_pkg.test1(1) from dual then output should
be Jan..
and
select test_pkg.test1(null) from dual then it should display all elements from table1.
Jan                  1
Feb                  2
Mar                  3,
Thanks for your quick replay..

i need to read data from associative array without using loops is it possible,
No - you would need to create a SQL type and then use the TABLE operator to unnest the collection.
create or replace TYPE my_nums IS TABLE OF INTEGER;
DECLARE
-- TYPE my_nums IS TABLE OF PLS_INTEGER INDEX BY PLS_INTEGER;
v_nums my_nums := my_nums(1, 2, 3);
v_total number;
BEGIN
select sum(column_value) into v_total from table(v_nums);
DBMS_OUTPUT.PUT_LINE
    ('Sum of the numbers is ' || TO_CHAR(v_total));
END;
Sum of the numbers is 6

Is there a way to remove elements from an array 1 by 1?

I have an two arrays, and they vary in size depending on a parameter set by the user (both arrays are the same size though, they both can vary in length). What I need to do, is remove elements one by one from the array, and use these as indices for another array. Basically, I built two arrays to store x-values on a graph. At the first value on the first array, I want y values on the graph to move from 0 to Y (any value). Then on the first value on the second array, I want the y values to move back from Y to 0 (creating a pulse, essentially, from the first value on the first array and the first value on the second array). By having each x value act as an indice for the y array, I belive I can acc
omplish this (ie, y =0 up to indice 90, then y = 5, then at indice 100, y goes back to equaling 0). I know this is poorly phrased, but it's difficult to explain. If anyone could help me out, I'd really appreciate it.

jdaltonnal,
Note: to add an attachment based on your comment of 6/12/01 to my earlier reply, I had to go back to this 'answer' mode, which gives me the option of adding attachments.
Per your comment, you have a sequence, so I've added a simple sequence structure and the 2nd array to provide a 250ms delay between each array output. Let me know...Doug
Attachments:
arrayindexplus1withseqdelays.vi ‏27 KB

Constructing a linked list from an array of integers

How do I create a linked list from an array of 28 integers in a constructor? The array of integers can be of any value that we desire. However we must use that array to test and debug methods such as getFirst(), getLast(), etc...
I also have a method int getPosition(int position) where its suppose to return an element at the specified position. However, I get an error that says cannot find symbol: variable data or method next()
public int getPosition(int position){
     LinkedListIterator iter=new LinkedListIterator();
     Node previous=null;
     Node current=first;
     if(position==0)
     return current.data;
     while(iter.hasMore()){
     iter.next();
     if(position==1)
     return iter.data;
     iter.next();
     if(position==2)
     return iter.data;
     iter.next();
     if(position==3)
     return iter.data;
     iter.next();
     if(position==4)
     return iter.data;
     iter.next();
     if(position==5)
     return iter.data;
     iter.next();
     if(position==6)
     return iter.data;
     iter.next();
     if(position==7)
     return iter.data;
     iter.next();
     if(position==8)
     return iter.data;
     iter.next();
     if(position==9)
     return iter.data;
     iter.next();
     if(position==10)
     return iter.data;
     iter.next();
     if(position==11)
     return iter.data;
     iter.next();
     if(position==12)
     return iter.data;
     iter.next();
     if(position==13)
     return iter.data;
     iter.next();
     if(position==14)
     return iter.data;
     iter.next();
     if(position==15)
     return iter.data;
     iter.next();
     if(position==16)
     return iter.data;
     iter.next();
     if(position==17)
     return iter.data;
     iter.next();
     if(position==18)
     return iter.data;
     iter.next();
     if(position==19)
     return iter.data;
     iter.next();
     if(position==20)
     return iter.data;
     iter.next();
     if(position==21)
     return iter.data;
     iter.next();
     if(position==22)
     return iter.data;
     iter.next();
     if(position==23)
     return iter.data;
     iter.next();
     if(position==24)
     return iter.data;
     iter.next();
     if(position==25)
     return iter.data;
     iter.next();
     if(position==26)
     return iter.data;
     iter.next();
     if(position==27)
     return iter.data;
     iter.next();
     if(position==28)
     return iter.data;
     if(position>28 || position<0)
     throw new NoSuchElementException();
     }

How do I create a linked list from an array of 28 integers
in a constructor? In a LinkedList constructor? If you check the LinkedList class (google 'java LinkedList'), there is no constructor that accepts an integer array.
In a constructor of your own class? Use a for loop to step through your array and use the LinkedList add() method to add the elements of your array to your LinkedList.
I get an error that
says cannot find symbol: variable data or method
next()If you look at the LinkedListIterator class (google, wait for it...."java LinkedListIterator"), you will see there is no next() method. Instead, you typically do the following to get an iterator:
LinkedList myLL = new LinkedList();
Iterator iter = myLL.iterator();
The Iterator class has a next() method.

Get value from the array based on the HashCode

public static void runJoin(int[][] t1,int[][] t2)
     PrintWriter out=null;
     int rows = 1000;
     int cols = 7;
     int [][] myTable3 = new int[rows][cols];
     int x = 0;
     System.out.print("Running HashJoin:Method loads the "+
     "smaller table in the memory and applies a hashing function "+
     "to common column and stores it in another table. "+
     "The larger table is then read from the file. "+
     "The same hashing function is applied to Col n of the table and a       matching record in the first table is looked up. A match will create a row in Table 3. ");
//Apply hashing function to smaller table and store it in the memory.
          Integer[] It2 = new Integer[t2.length];
          int [] hashCodest2 = new int[t2.length];
          Hashtable ht = new Hashtable();
          for(int i =0; i <t2.length;i++){
               It2[i] = new Integer(t2[0]);
               hashCodest2[i] = It2[i].hashCode();
               ht.put(new Integer(hashCodest2[i]),It2[i]);
          //Larger table get hashcodes
          Integer It1[] = new Integer[t2.length];
          int [] hashCodest1 = new int[t2.length];
          for(int j =0; j <t1.length;j++){
               It1[j] = new Integer(t1[j][4]);
               hashCodest1[j] = It1[j].hashCode();               }
          //Based on the hashcode get the value from the Table2;
          try{
out = new PrintWriter( new FileOutputStream( "c:\\HashJoinTable.txt" ) );
          Enumeration e = ht.keys();
               while(e.hasMoreElements())
//How do I get the value from the array based on the HashCode? Do I need to do a loop here???
hashCodes1.get(e.nextElement());
          }catch(Exception e){}

ok I got it......
          //Apply hashing function to smaller table and store it in the memory.
          Integer[] It2 = new Integer[t2.length];
          int [] hashCodest2 = new int[t2.length];
          Hashtable ht = new Hashtable();
          for(int i =0; i <t2.length;i++){
               It2[i] = new Integer(t2[0]);
               hashCodest2[i] = It2[i].hashCode();
               ht.put(new Integer(hashCodest2[i]),It2[i]);
          //Larger table get hashcodes and compare
          Integer It1[] = new Integer[t2.length];
          int [] hashCodest1 = new int[t2.length];
          Hashtable ht2 = new Hashtable();
          for(int j =0; j <t1.length;j++){
               It1[j] = new Integer(t1[j][4]);
               hashCodest1[j] = It1[j].hashCode();
               ht2.put(new Integer(hashCodest1[j]),It1[j]);
          //Based on the hashcode get the value from the Table2;
          try{
out = new PrintWriter( new FileOutputStream( "c:\\HashJoinTable.txt" ) );
          Enumeration e = ht.keys();
          Integer t3[] = new Integer[t2.length];
               while(e.hasMoreElements())
                    t3[x] = (Integer) ht2.get(e.nextElement());
                    x++;
          }catch(Exception e){}

Determining which method to call from an array of Objects

Hi All,
Lets suppose I have an interface, a string method name, and an array of Objects indicating the parameters which should be passed to the method.
What Im trying to work out is a way to quickly determine which method should be invoked.
I can see that Class has getDeclaredMethod(String, Class[]), but that wont help me as I dont know the formal class types (the method may take X, but I might get passed Y which extends X in the array of objects).
Does anyone know of a quick way I can determine this?
All I can think of at the moment is going thru each method of the class one by one, and seeing if the arg is assignable, then, after getting all my matched methods, determining if there are any more 'specific' matches.
Any ideas?
Much appreciated,
Dave

you might want to take a look at the dynamic proxy apiCheers for the suggestion, but Im actually already using the dynamic proxy API.
What I have is a MockObjectValidator which allows mock objects to be configuered with expected calls, exceptions to throw etc etc.
I thought developers on my project would get tired using an interface like this:
myValidator.setExpectedCall("someMethod", new Class[] { typeA, typeB }, new Object[] { valueA, valueB} );
I.e, I wanted to cut out having to pass the class array, so they could just use:
myValidator.setExpectedCall("someMethod", new Object[] { valueA, valueB} );
The problem there is that I then need to pick the best Method from the class given the object arguments.
When the mock object is in use, its no problem as the InvocationHandler interface provides the Method. The problem I have is selecting what method a user is talking about from an array of Objects.
Ive written a simple one now, it just does primitive type class -> wrapper substitution, and then finds ** A ** match. If there is more than one match (ie, all params are assignable to a class' method params), I dont let that method be used.
Shortly I'll update it to actually make the correct selection in those cases.
cheers
Dave

Remove specific row and column from 2d array

Hi,
I would like to know how to remove the specific row and column from 2d array.
for example, I have the original 4x4 array as below
2 -1 -1 0
-1 2 0 -1
-1 -1 2 0
-1 -1 -1 3
let say that i want to remove row 2(bold) and column 2(bold), and the new 2d array should get as below
2 -1 0
-1 2 -1
-1 -1 3
Thanks.

You can't remove elements of an array, it's fixed at a certain size once created. What you can do however is make a new array and only copy the things you want. Something like:public static void main(String[] args) {
    Integer[][] bar = new Integer[5][5];
    for (int i = 0; i < bar.length; i++) {
        Integer[] baz = bar;
Arrays.fill(baz, i);
System.out.println(Arrays.toString(baz));
Integer[][] muu = new Integer[5][4];
removeColumn(3, bar, muu);
for (Integer[] mee : muu) {
System.out.println(Arrays.toString(mee));
Integer[][] smuu = new Integer[4][5];
removeRow(3, bar, smuu);
for (Integer[] mee : smuu) {
System.out.println(Arrays.toString(mee));
public static <T> void removeRow(int row, T[][] a, T[][] result) {
if (row >= a.length) {
throw new IllegalArgumentException("no row at " + row);
for (int a_r = 0, result_r = 0; a_r < a.length; a_r++) {
if (a_r == row) {
continue;
System.arraycopy(a[a_r], 0, result[result_r], 0, a[a_r].length);
result_r++;
public static <T> void removeColumn(int col, T[][] a, T[][] result) {
for (int i = 0; i < a.length; i++) {
if (col >= a[i].length) {
throw new IllegalArgumentException("no column at [" + i + ", " + col + "]");
for (int a_i = 0, r_i = 0; a_i < a[i].length; a_i++) {
if (a_i == col) {
continue;
result[i][r_i] = a[i][a_i];
r_i++;

What is the best way to move data from one array to another

I'm going to be moving data from one array to a larger array on the same RAID but different controller. (I have some extra extra drives I'm also going to be installing Retrospect so I can't just restore from a backup.)
The RAID has 450GB of production files, fonts etc.
What is the best way to move the data over?
I saw that someone had suggested using ditto. Would that be better than MacMV?
I also own Bru LE so I could use that.
Any advice would be appreciated.
Thanks,
Paul

Ditto is a great option -- probably the best.
ditto -rsrc src_folder /Volumes/targetvolume/targetfolder

Sending a array of integer to client

Hi all,
I'm new to socket programming and i had read many tutorials on sending files from server to client using DataOutputStream. Is it possible to send a array of integer out using DataOutputStream? If so any example or tutorial that i can read on? Thanks.

Alternatively, can i convert the array of integer to byte and transfer to the client and covert it back to array of integer again?
Can someone help me with this?
Example:
//I have a array of integer
testArray = new int[10];
int i;
for(i=0;i<10;i++) {
testArray[i] = i;
//I need some code to send this array of integer to a client.

Display an image from an array of bytes

Hi, I'm trying to display an image from the raw pixel values. lets say i read a bmp file to an array, chuk the header off and want to display the pixel. How can I do this? I don't want any file formats, just want to display the pixels and creat the image. Is this possible?
Many thanks,
H

Thanks for the reply. I had a look at MemoryImageSource and other classes that relates to it. I wrote the example given, but it doesn't identify createImage(). I've implemented ImageProducer, but still complains. Have you any idea why? Thanks for your help.
H

Going from an array of integer pixels to a saved image (JPEG etc)

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