How to dismiss a Snackbar using it’s own Action button?

For Java,

The .make method returns a Snackbar object. Save an instance of that object by making it final. Then, in the onClick(), call .dismiss:

final Snackbar snackBar = Snackbar.make(findViewById(android.R.id.content), "Snackbar Message", Snackbar.LENGTH_LONG);

        snackBar.setAction("Action Message", new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // Call your action method here
                snackBar.dismiss();
            }
        });
        snackBar.show();

For Kotlin,

        Snackbar.make(
            findViewById(android.R.id.content),
            "Snackbar Message",
            Snackbar.LENGTH_INDEFINITE
        ).setAction("Action Message") {
            // Call action functions here
        }.show()