Vector of vectors

[inox]

Hello everybody,

I am trying to figure out how I can have vector of vectors. Basically what I want to do is to have something like below

VectorN = [ [vector_a],[vector_b],[vector_c],...,[vector_n] ]

VectorN is comprises of a series of another vector where each consists of 3 values ([vector_a] = [int x, int y, int z]

I really appreciate the helps.

Thanking in advance :-)

[Belisarius]

A Vector is an Object. Vectors contain Objects. Ergo, a Vector can contain Vectors just like any other Object.

It sounds like you might want to create a new class to contain your values rather than use a Vector. Unless you're using Java 1.5, you'll have a lot of casting back and forth, as those ints will need to be put into Integers and then pulled out.

You can then put your new class into a Vector (although I'd suggest ArrayList as a lighter-weight class).

[inox]

Hi Belisarius,

Thanks for your prompt reply. I am currently using Java 1.4. If I still want to use Vector, do you suggest I'll have Java 1.5 instead? Or is it more advisable for me to work with ArrayList? Can ArrayList provide me with the same result as I want like the one in Vector?

Actually I want to store each rgb values for a pixel of an image into say a Set so that any rgb with redundant values will be omitted which allow me to count the numbe of colours in the image. I later would like to have access again to these values for further processing.

Your idea(s) are most welcome and indeed needed.

Thanks...

[Belisarius]

Vector is just an old class that was jury-rigged into the collections framework. ArrayList is basically the same thing, only built from the ground up to be part of Collections. Vector has been kept around for backwards compatability, but it's a little bit heavy for what most people want to use it for.

Now, what I would do is write yor own Pixel object.

public class Pixel extends java.awt.Point implements Comparable{
  private int red;
  private int green;
  private int blue;
  
  public Pixel() {
    super();
    init(0,0,0,0,0);
  }
  
  public Pixel(int red, int green, int blue){
    super();
    init(0, 0, red, green, blue);
  }
  
  public Pixel(int x, int y, int red, int green, int blue){
    super();
    init(x, y, red, green, blue);
  }
  
  private void init(int x, int y, int red, int green, int blue){
    super.setLocation(x, y);
    this.red = red;
    this.green = green;
    this.blue = blue;    
  }
  
  public boolean compareTo(Pixel input){
    // Write your compareTo method here
  }
  
  public String toString(){
    // Write your toString method here    
  }
  
  public boolean equals(Pixel input){
    // Write your equals method here
  }
  
  public int hashCode(){
    // Write your hashCode method if you plan on using something that requires
    // a hash.
  }

  public int getRed() {
    return red;
  }

  public void setRed(int red) {
    this.red=red;
  }

  public int getGreen() {
    return green;
  }

  public void setGreen(int green) {
    this.green=green;
  }

  public int getBlue() {
    return blue;
  }

  public void setBlue(int blue) {
    this.blue=blue;
  }
}

Be sure to write the compareTo() and equals() methods. You can then add them to a Set (say . . . TreeSet). This will store only unique Pixels. If you want, you can write your own Comparator and pass it to the TreeSet constructor should you wish to consider *only* colors and not position, while not tainting the default method of comparison for Pixel. In other words, pixels with the same RGB values but different XY values would be, by default, different. If you only wanted to consider similar RGB values, you could write an anonymous Comparator, and pass it to the TreeSet when you create it. It would then include only unique RGB values, regardless of XY position.

[inox]

Thanks Bel for the lengthy explanation and of course the pixel object class. Really appreciate it. I will try this straight away.