Getting exception in assignment of a value to array in android

Question

I am trying to read an Image pixel by pixel and want to save the pixel RGB value in arrays. but when trying to do so I am getting an exception in the statement
R[i]=redValue;
Someone please suggest what I might doing wrong?

please find the exception stack trace here -

paste.ubuntu.com/6216208

public class AnalyzeImage extends Activity  
{   
    int []R;  
    int []G;  
    int []B;  
    int width, height, i=0;  
    int a=1;  
    public int analyzeImagefunc(Bitmap bitmap)
    {            
    try{ 
     width  =  bitmap.getWidth();
     height = bitmap.getHeight();
     i = 0;
     for(int x = 0;x < width;x++)
     {
      for(int y = 0;y < height;y++)
      {
      int pixel = bitmap.getPixel(x,y);         
      int redValue = Color.red(pixel);
      int blueValue = Color.blue(pixel);
      int greenValue = Color.green(pixel);
      a=5;
      R[i]=redValue; 
      a=6;
      i++;
       }
      } 
     }

    catch(Exception e)
        {
            //nothing
        }
     return a;
 }  
}

Array is not initialized

newuser
– newuser

2013-10-10 06:24:49 +00:00
Commented Oct 10, 2013 at 6:24 — newuser
– newuser, Commented Oct 10, 2013 at 6:24

Juned Ahsan · Accepted Answer · 2013-10-10 06:27:31Z

3

Your arrays need to be initialzed first before using. You have jsut declared the arrays:

int []R;  
int []G;  
int []B;

but not initialized them.So if you try to access any array element it will throw null pointer exception. Try to initialized your array like:

int []R = new int[10];  
int []G = new int[10];  
int []B = new int[10];

You can change the size of arrays as per your need.

answered Oct 10, 2013 at 6:27

Juned Ahsan

68.9k12 gold badges101 silver badges138 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

newuser · Accepted Answer · 2013-10-10 06:37:19Z

2

int []R;
int []G;
int []B;

R, G, B is not initialized any where.

initialize the R

 width  =  bitmap.getWidth();
 height = bitmap.getHeight();
 i = 0;
 int size = height * width;
 R = new int[size]; // initialize the size of array R   
 for(int x = 0;x < width;x++)

edited Oct 10, 2013 at 6:37

answered Oct 10, 2013 at 6:25

newuser

8,4862 gold badges28 silver badges33 bronze badges

Comments

Brijesh Patel · Accepted Answer · 2013-10-10 06:41:59Z

Array need initialization with fix size. so if array's size is not fix then you should go with ArrayList. and also you can cast ArrayList to array if needed for final output.

    public class AnalyzeImage extends Activity {
        int[] R;
        int[] G;
        int[] B;
        ArrayList<Integer> R_Lst = new ArrayList<Integer>();
        ArrayList<Integer> G_Lst = new ArrayList<Integer>();
        ArrayList<Integer> B_Lst = new ArrayList<Integer>();

        int width, height, i = 0;
        int a = 1;

        public int analyzeImagefunc(Bitmap bitmap) {
            try {
                width = bitmap.getWidth();
                height = bitmap.getHeight();
                i = 0;
                for (int x = 0; x < width; x++) {
                    for (int y = 0; y < height; y++) {
                        int pixel = bitmap.getPixel(x, y);
                        int redValue = Color.red(pixel);
                        int blueValue = Color.blue(pixel);
                        int greenValue = Color.green(pixel);
                        a = 5;
//                      R[i] = redValue;
                        R_Lst.add(redValue);
                        B_Lst.add(blueValue);
                        G_Lst.add(greenValue);
                        a = 6;
                        i++;
                    }
                }
            }

            catch (Exception e) {
                // nothing
            }
            R=convertIntegers(R_Lst);
            return a;
        }
        public int[] convertIntegers(List<Integer> integers)
        {
            int[] ret = new int[integers.size()];
            for (int i=0; i < ret.length; i++)
            {
                ret[i] = integers.get(i).intValue();
            }
            return ret;
        }

//      (Note that this will throw a NullPointerException if either integers or any element within it is null.)

want to save the pixel RGB value in arrays. He want to store the RGB values in Array

Philip Sheard · Accepted Answer · 2013-10-10 06:35:49Z

1

width = bitmap.getWidth();
height = bitmap.getHeight();
int n = width * height;
R = new int[n];  
G = new int[n];  
B = new int[n];
i = 0;

By implication, you also require:

R[i] = redValue;
G[i] = greenValue;
B[i] = blueValue;

answered Oct 10, 2013 at 6:35

Philip Sheard

5,8335 gold badges30 silver badges42 bronze badges

Collectives™ on Stack Overflow

Getting exception in assignment of a value to array in android

4 Answers 4

Comments

Comments

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related