android - Passing object to method in java appears to be by reference (and Java is by val)

I thought when you passed objects to methods in Java, they were supposed to be by value.

Here is my code:

public class MyClass{
    int mRows;
    int mCols;

    Tile mTiles[][];     //Custom class

    //Constructor
    public MyClass(Tile[][] tiles, int rows, int cols) {
        mRows = rows;
        mCols = cols;

        mTiles = new Tile[mRows][mCols];
        for (int i=0; i < mRows; i++) {
            for (int j=0; j < mCols; j++) {

                mTiles[i][j] = new Tile();
                mTiles[i][j] = tiles[i][j];
            }
        }
    }

At this point, any changes to the mTiles object are reflected back to the tiles object. Any ideas how to fix this?

Thanks all.