Grid. Select first row per default

Flow
2

Vaadin Flow Grid has method Grid.select(item), which selects item programmatically. So you need to resolve the item. The best way to get it, is to use Grid.getDataCommunicator() which has the following method, fetchFromProvider:

https://demo.vaadin.com/javadoc/com.vaadin/vaadin-core/10.0.2/com/vaadin/flow/data/provider/DataCommunicator.html#fetchFromProvider-int-int-

So fetchFromProvider(1,1) returns a stream of one item you want to select.