How to check gravity flags in a custom Android View?

You can examine how FrameLayout lays its children. Particularly, this code:

final int layoutDirection = getLayoutDirection();final int absoluteGravity = Gravity.getAbsoluteGravity(gravity, layoutDirection);final int verticalGravity = gravity & Gravity.VERTICAL_GRAVITY_MASK;switch (absoluteGravity & Gravity.HORIZONTAL_GRAVITY_MASK) {    case Gravity.CENTER_HORIZONTAL:        ...    case Gravity.RIGHT:        ...    case Gravity.LEFT:        ...}switch (verticalGravity) {    case Gravity.TOP:        ...    case Gravity.CENTER_VERTICAL:        ...    case Gravity.BOTTOM:        ...}

There're masks in Gravity class: VERTICAL_GRAVITY_MASK, HORIZONTAL_GRAVITY_MASK which will help you to find out what gravities have been applied.

This is a supplemental answer to @azizbekian's very helpful solution. I'm adding this to help myself more fully understand how gravity works behind the scenes.

Horizontal axis gravity

LEFT and RIGHT are known as absolute gravity. That is, if a user specifies a relative gravity of START or END, then it is converted internally to an absolute gravity of RIGHT or LEFT depending on the situation.

0000 0001  CENTER_HORIZONTAL0000 0011  LEFT0000 0101  RIGHT---------  0000 0111  HORIZONTAL_GRAVITY_MASK

A note about START and END

1000 0000 0000 0000 0000 0011  START0000 0000 0000 0000 0000 0011  LEFT1000 0000 0000 0000 0000 0101  END0000 0000 0000 0000 0000 0101  RIGHT-----------------------------0000 0000 0000 0000 0000 0111  HORIZONTAL_GRAVITY_MASK

As you can see here, START and LEFT only differ by a single bit. It is the same for END and RIGHT. Thus, if you use the HORIZONTAL_GRAVITY_MASK directly on START and END, they will default to LEFT and RIGHT respectively. However, this should be used with caution. Right-to-left language locales should be taken into consideration.

Vertical axis gravity

The y axis gravity is shifted over 4 bits from the x axis (horizontal) gravity.

0001 0000  CENTER_VERTICAL0011 0000  TOP0101 0000  BOTTOM---------0111 0000  VERTICAL_GRAVITY_MASK

Both axes

Note that CENTER is a combination of CENTER_VERTICAL and CENTER_HORIZONTAL. Thus, you can also use one of the gravity masks to convert it.

0000 0001  CENTER_HORIZONTAL0001 0000  CENTER_VERTICAL0001 0001  CENTER---------0000 0111  HORIZONTAL_GRAVITY_MASK0111 0000  VERTICAL_GRAVITY_MASK

Bit math

Use the bit OR operator (|) to combine horizontal and vertical gravity.

Example:

int myGravity = Gravity.RIGHT | Gravity.BOTTOM;0000 0101  RIGHT0101 0000  BOTTOM---------0101 0101  myGravity

Use the bit AND operator (&) with one of the gravity masks to isolate the horizontal or vertical gravity.

Example

int verticalGravity = myGravity & Gravity.VERTICAL_GRAVITY_MASK;if (verticalGravity == Gravity.BOTTOM) ...0101 0101  myGravity0111 0000  VERTICAL_GRAVITY_MASK---------0101 0000  verticalGravity0101 0000  BOTTOM