Is it possible to set permission to other user for the table created by current user with PostgreSQL?

In PostgreSQL, created these 2 roles and grant different permissions to them.

create user user1 with login; create role operator; grant operator to user1;  create user user2 with login; create role readwrite; grant readwrite to user2; 

When created a table by user1, such as table1, user2 can’t use this table. It got permission denied.

Is it the right feature for PostgreSQL? If it is, how to make the table also can be used for user2?