How to interact with alertdialog in Espresso?

I have a test in which I have a Alertdialog on which there is an "input" field and buttons "Cancel"(id is button2) and "Ok"(id is button1). First I have to enter the value "1234" in the field, and then click on the "Ok" button. But it doesn’t work for me, the test fails.

    onView(withId(R.id.input)).perform(typeText("1234"));
    closeSoftKeyboard();
    click(R.id.button1);
    Thread.sleep(5000);