How to access a 2D array inside an object?

Question

I am getting an object as a result of a method call. It is a raster/grid/matrix with rows and columns. But the return type of the method is a object.

On debugging, I can see the 2D array inside. But I am not being able to cast it into anything.

Object vPixels = pixelblock3.getPixelDataByRef(0);
Integer[][] wPixels = (Integer[][]) vPixels;

I get a ClassCastException at the 2nd line: [[B cannot be cast to [[Ljava.lang.Integer;

How can I fix this problem?

Luigi · Accepted Answer · 2012-12-30 21:08:56Z

3

Just a guess: try:

int[][] wPixels = (int[][]) vPixels;

Or

byte[][] wPixels = (byte[][]) vPixels;

I think that [[B, "B" means primitive bytes.

answered Dec 30, 2012 at 21:08

Luigi

8,8558 gold badges56 silver badges67 bronze badges

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

1 Comment

you're welcome. If the JVM was more kind, it should have pointed somehow byte instead of a cryptic B :)

pinco · Accepted Answer · 2012-12-30 21:18:13Z

0

A simple trick to know what is the type of the object:

Object vPixels = pixelblock3.getPixelDataByRef(0);
Class cls = vPixels.getClass();
System.out.println("The type of the object is: " + cls.getName());

Then you can cast to the appropriate type.

EDIT: as Luigi pointed out [[B means byte[][] so his answer is the correct one.

answered Dec 30, 2012 at 21:11

pinco

8882 gold badges14 silver badges27 bronze badges