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

@param i the row index (0, 1, or 2)
@param store storage for the result, or null for a new Vector3f
@return either {@code store} or a new Vector3f
@throws IllegalArgumentException if {@code i} isn't 0, 1, or 2
jme3-core/src/main/java/com/jme3/math/Matrix3f.java