Are generics supported in developer console?

Question

Reading Can you use generics in Apex? generics are supported in apex. When I attempt to run the below trigger in developer console:

trigger TotalTriggerAccount on Account (after update) {
 
    System.debug('Updating account');
    
    String accountId = ApexPages.currentPage().getParameters().get('id');

    List<Contact> allContacts = [
      SELECT
        *
      FROM
        Contact
      WHERE
        AccountId = :accountId
    ];
    
    for (Contact contact : allContacts) {
      System.debug(contact.Phone);
    }
    
}

to access all contacts for a given account I receive multiple Problems related to the use of generics and the declaration of the array such as:

Unexpected token '<'.
Unexpected token '>'.
Unexpected token ']'.

Is there a stop required in order to use generics and array elements in apex for developer console ?

Update:

By developer console, I refer to:

To add a new trigger from the developer console:

Answer 1

You cannot define a trigger in Execute Anonymous, which is what causes the other compilation errors. You are generally allowed to use parameterized typing in Execute Anonymous and code units (classes and triggers).

Also, you may be receiving errors because of the * in your field list. SOQL does not support the "all fields" operator found in SQL; you must explicitly list each field you want to retrieve. Because SOQL does not explicitly support this wildcard, it often causes unrelated compilation errors, such as the ones you've mentioned. In fact, writing invalid SOQL almost always causes unrelated compilation errors.