Conversion from Vector<double[]> to double[][]

How can I convert Vector&开发者_JS百科lt;double[]> to double[][] in java ?

---

You can convert a Vector to an array by Vector.toArray():

double[][] array = vector.toArray(new double[0][]);

This maybe slightly faster then for loop, because Vector can utilize System.arraycopy() on its internal array.

---

This will do it:

double matrix[][] = new double[vector.size()][];
for (int i = 0; i < vector.size(); i++) {
    matrix[i] = vector.get(i);
}

Note that this references the same double[] arrays as in your Vector<double[]>. So a change in that will be reflected in the new matrix[][]. If you don't want that then you'll have to create a new double[] for each iteration and copy the values from the old array to the new array.

---

Muhammed,

WhiteFang is correct... if you're looking for an "out of the box" solution then have a look at Apache's Commons Collections (http://commons.apache.org/collections/)

It's been over a year since I touched Java, but if I recall correctly, "commons" has converters for Vectors... as well as many, many, many other handy bits of kit.

And BTW: If using a Vector is your choice, and you don't have a good reason to NOT use an ArrayList, then use an ArrayList... It's slightly quicker. Except it's NOT threadsafe; whereas all Vectors methods are syncronised. Explanation here: http://skeletoncoder.blogspot.com/2006/09/java-tutorials-arraylist-or-vector.html.

Cheers. Keith.