public class Advertisement{
    private int ID;
    private String description;
    // 构造函数
    public Advertisement(int ID, String description){
        this.ID = ID;
        this.description = description;
    }
    public int getID() {
        return ID;
    }

public class PrintedAd extends Advertisement{
        private int First;   //第一页成本
        private int Middle;  //中间页成本
        private int Last;    //最后一页成本
    public PrintedAd(int First, int Middle, int Last){
        this.First = First;
        this.Middle = Middle;
        this.Last = Last;
    }
    public int getFirst() {
        return First;
    }

public class Main{
    public static void main(String[] args) {
        
        Advertisement ad = new Advertisement(34567, "test");
        System.out.println(ad.getID());
        PrintedAd ad2 = new PrintedAd(10,20,30);
        System.out.println(ad2);
    }
}

    private int ID;
    private String description;
    // 构造函数
    public Advertisement(int ID, String description){
        this.ID = ID;
        this.description = description;
    }

PrintedAdd ad2 = new PrintedAdd(10,20,30);

// 在这里是你的超类代码

// 在这里是你的子类代码

// 在这里是你的应用程序代码

// 在这里是运行时输出

<details>
<summary>英文:</summary>
In your code:
    PrintedAdd ad2 = new PrintedAdd(10,20,30);
This new `PrintedAdd` object (also an `Advertisement`) has `null` in its two inherited member fields, `ID` and `description`. You neglected to invoke a constructor (or setters) to specify those values, so they default to `null`.  
So yes, if you want a subclass to have 5 fields, 2 inherited, and 3 defined on the subclass itself, at run time you need to pass 5 values (primitives or object references). You can pass to a constructor, and/or you can pass via setter methods. Or you could use a [dependency injection][1] framework such as [*Jakarta Contexts and Dependency Injection*][2], [*Google Guice*][3], or [*Spring*][4]. Otherwise, you get default values in member field; for object references that means `null`. 
In your particular case, your objects are read-only, with getters but no setters. So that eliminates the setters option. And in your case, a dependency injection framework is not appropriate, as that is for providing resources and services, not for individual values such as an ID or description. So, that leaves the constructor option. &#128073; You should write the subclass to have a constructor taking 5 arguments, for the 2 inherited fields and the 3 subclass-specific fields.
Be aware that a subclass’ constructor can call a superclass’ constructor. See existing Question such as [*Calling superclass from a subclass constructor in Java*](https://stackoverflow.com/q/19326229/642706). 
Here is some example code, and some notes.
- Your superclass should be marked `abstract` as you intend only to instantiate the subclasses, never the superclass. You may want to read [*Constructors in Java Abstract Classes*](https://www.baeldung.com/java-abstract-classes-constructors) by [baeldung][5]. And read Question, [*Can an abstract class have a constructor?*](https://stackoverflow.com/q/260666/642706). 
- Since you know all subclasses at compile time, and do not expect new ones to be dynamically added at runtime, you can [seal the superclass][6]. Sealed classes and interfaces restrict which other classes or interfaces may extend or implement them. (Not important for your Question, just a note for modern Java programming.)
- In Java naming conventions, a member field should be name with an initial lowercase letter. So, `first`, not `First`. And `id`, not `ID`. All uppercase by convention means a [constant][7]. 
- For simplicity, I replaced your multiple member fields on `PrintAd` to a single `LocalDate`. 
- &#128073; Note how it makes sense to pass the id and description in each constructor — there is no other way to discern what the value should be for those fields.
The superclass:
```java
package work.basil.example.advertising;
import java.util.Objects;
import java.util.UUID;
public abstract sealed class Advertisement
        permits PrintAd, WebAd, RadioAd
{
    // Member fields. Read-only, via getter methods.
    private final UUID id;
    private final String description;
    // Constructors
    public Advertisement ( final UUID id ,
                           final String description )
    {
        this.id = id;
        this.description = description;
    }
    // Getters
    public UUID getId ( )
    {
        return id;
    }
    public String getDescription ( )
    {
        return description;
    }
    // `Object` overrides
    @Override
    public boolean equals ( Object o )
    {
        if ( this == o ) return true;
        if ( o == null || getClass ( ) != o.getClass ( ) ) return false;
        Advertisement that = ( Advertisement ) o;
        return Objects.equals ( id , that.id );
    }
    @Override
    public int hashCode ( )
    {
        return Objects.hash ( id );
    }
    @Override
    public String toString ( )
    {
        return &quot;Advertisement[&quot; +
                &quot;id=&quot; + id + &quot;, &quot; +
                &quot;description=&quot; + description + &#39;]&#39;;
    }
}

package work.basil.example.advertising;
import java.time.LocalDate;
import java.util.UUID;
public final class PrintAd extends Advertisement
{
    private final LocalDate runDate;
    public PrintAd ( final UUID id , final String description , final LocalDate runDate )
    {
        super ( id , description );
        this.runDate = runDate;
    }
    public LocalDate getRunDate ( )
    {
        return runDate;
    }
}

package work.basil.example.advertising;
import java.net.URL;
import java.util.UUID;
public final class WebAd extends Advertisement
{
    private final URL url;
    public WebAd ( final UUID id , final String description , final URL url )
    {
        super ( id , description );
        this.url = url;
    }
    public URL getUrl ( )
    {
        return url;
    }
}

package work.basil.example.advertising;
import java.time.LocalTime;
import java.util.UUID;
public final class RadioAd extends Advertisement
{
    private final LocalTime airTime;
    public RadioAd ( final UUID id , final String description , final LocalTime airTime )
    {
        super ( id , description );
        this.airTime = airTime;
    }
    public LocalTime getAirTime ( )
    {
        return this.airTime;
    }
}

package work.basil.example.advertising;
import java.net.MalformedURLException;
import java.net.URI;
import java.time.LocalDate;
import java.time.LocalTime;
import java.util.List;
import java.util.UUID;
public class App
{
    public static void main ( String[] args )
    {
        App app = new App ( );
        app.demo ( );
    }
    private void demo ( )
    {
        List < Advertisement > ads = null;
        try
        {
            ads =
                    List.of (
                            new PrintAd (
                                    UUID.fromString ( "a71330e7-131f-4d10-beac-4e8ffc21887f" ) ,
                                    "Example print ad." ,
                                    LocalDate.now ( )
                            ) ,
                            new WebAd (
                                    UUID.fromString ( "8aafa2cf-03dc-452b-a84d-c61d75964955" ) ,
                                    "Example web ad." ,
                                    URI.create ( "https://www.DailyBugle.com/ads" ).toURL ( )
                            ) ,
                            new RadioAd (
                                    UUID.fromString ( "e21b187c-01e2-44da-9a26-5debb9146cf6" ) ,
                                    "Example radio ad." ,
                                    LocalTime.NOON
                            )
                    );
        }
        catch ( MalformedURLException e ) { throw new RuntimeException ( e ); }
        System.out.println ( "ads = " + ads );
    }
}

public class Advertisement {
    private static int universalId = 0;
    private int ID;
    private String description;
    protected Advertisement() {
        ID = universalId++;
    }
    public Advertisement(String description) {
        this();
        this.description = description;
    }
    public int getID() {
        return ID;
    }
}

public class PrintedAdd extends Advertisement {
    private int First;   //first page cost
    private int Middle;  //middle page cost
    private int Last;    //last page cost
    public PrintedAdd(int First, int Middle, int Last) {
        super();
        this.First = First;
        this.Middle = Middle;
        this.Last = Last;
    }
    public int getFirst() {
        return First;
    }
}