public Matrix3f setRow(int i, Vector3f row) {
        if (row == null) {
            logger.warning("Row is null. Ignoring.");
            return this;
        }
        switch (i) {
            case 0:
                m00 = row.x;
                m01 = row.y;
                m02 = row.z;
                break;
            case 1:
                m10 = row.x;
                m11 = row.y;
                m12 = row.z;
                break;
            case 2:
                m20 = row.x;
                m21 = row.y;
                m22 = row.z;
                break;
            default:
                logger.warning("Invalid row index.");
                throw new IllegalArgumentException("Invalid row index. " + i);
        }
        return this;
    }
Sets the specified row.

@param i which row to set (0, 1, or 2)
@param row the desired element values (unaffected) or null for none
@return the (modified) current instance (for chaining)
@throws IllegalArgumentException if {@code i} isn't 0, 1, or 2
jme3-core/src/main/java/com/jme3/math/Matrix3f.java