Netbeans told that "declared variable" is a package that does not exist

Question

It happened when I tried to use a ListSelectionModel.

Did I made some mistake?

Answer 1

You typed the statement at the wrong spot:

class X {

    HERE - WHERE THE FIELD DECLARATIONS GO

    X() {
        STATEMENT SHOULD GO HERE
    }

The compiler thinks to deal with a declaration, starting with a class, which may be x.y.z.C.

Answer 2

You need to invoke the statement in a code block such as a method or constructor rather than the class block.

class AdminConsole ... {

    void initComponents() {
       ...
       table.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
       ...
    }
}

Side note: setSelectionMode is undefined for ListSelectionModel - instead it needs to be invoked on the JTable