public interface CarBridge

Internal service-provider interface implemented by each platform port to render the portable com.codename1.car template tree onto the native in-car UI (Apple CarPlay’s CPTemplate hierarchy or Google Android Auto’s androidx.car.app templates).

Application code never touches this interface – it is obtained by the com.codename1.car framework classes from com.codename1.ui.Display#getCarBridge() and driven through the public com.codename1.car.CarContext / com.codename1.car.CarScreen API. The base implementation returns null, which is why the public API degrades to a harmless no-op on the simulator and on ports without an in-car projection (so application code needs no platform if statements).

A bridge renders a screen by pulling its template through CarScreen.createTemplate() (the framework calls CarScreen#dispatchCreateTemplate() on its behalf) and is responsible for invoking the relevant com.codename1.car.CarActionListener when the user activates a row, grid item or action – the bridge identifies the activated element by the indices it assigned while rendering.

Methods

`public abstract void pushScreen(CarScreen screen)`	Pushes a screen onto the in-car back stack and renders its template.
`public abstract void popScreen()`	Pops the top screen off the in-car back stack, returning to the previous screen.
`public abstract void invalidate(CarScreen screen)`	Re-pulls and re-renders the template for the supplied screen (call after mutating the model behind a screen, mirroring `androidx.car.app.Screen#invalidate()`).
`public abstract void finish()`	Tears down the in-car experience, dismissing the app from the head unit.
`public abstract boolean isConnected()`	Returns true while a head unit (CarPlay / Android Auto) is currently connected and the projected UI is live.
`public abstract void showToast(String message, int durationSeconds)`	Shows a short transient message on the head unit (CarPlay banner / Android Auto toast).
`public abstract int getListRowLimit()`	Returns the maximum number of rows the head unit will display in a single list, or `0` when the limit is unknown.
`public abstract int getGridItemLimit()`	Returns the maximum number of items the head unit will display in a single grid, or `0` when the limit is unknown.

Method details

pushScreen

public abstract void pushScreen(CarScreen screen)

Pushes a screen onto the in-car back stack and renders its template. The pushed screen becomes the visible top of stack.

Parameters

screen CarScreen: the screen to push and render

popScreen

public abstract void popScreen()

Pops the top screen off the in-car back stack, returning to the previous screen. Has no effect when only the root screen remains.

invalidate

public abstract void invalidate(CarScreen screen)

Re-pulls and re-renders the template for the supplied screen (call after mutating the model behind a screen, mirroring androidx.car.app.Screen#invalidate()). No effect if the screen is not currently on the stack.

Parameters

screen CarScreen: the screen whose template should be rebuilt

finish

public abstract void finish()

Tears down the in-car experience, dismissing the app from the head unit.

isConnected

public abstract boolean isConnected()

Returns true while a head unit (CarPlay / Android Auto) is currently connected and the projected UI is live.

Returns

true if a car is connected

showToast

public abstract void showToast(String message, int durationSeconds)

Shows a short transient message on the head unit (CarPlay banner / Android Auto toast).

Parameters

message String: the text to display
durationSeconds int: requested display duration in seconds; the head unit may clamp it

getListRowLimit

public abstract int getListRowLimit()

Returns the maximum number of rows the head unit will display in a single list, or 0 when the limit is unknown. Driver-distraction rules cap this aggressively (often 6-12); honour it when populating a com.codename1.car.CarListTemplate.

Returns

the row limit, or 0 if unknown

getGridItemLimit

public abstract int getGridItemLimit()

Returns the maximum number of items the head unit will display in a single grid, or 0 when the limit is unknown.

Returns

the grid item limit, or 0 if unknown