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1. Write a MongoDB query to display all the documents in the collection restaurants.
    db.restaurants.find().pretty()
or
     db.restaurants.find()
 
 2. Write a MongoDB query to display the fields restaurant_id, name, borough and cuisine for all the documents in the collection restaurant
 db.restaurants.find({}, {"restaurant_id":1, "name":1,"borough":1 , "cuisine":1})
    
3. Write a MongoDB query to display the fields restaurant_id, name, borough and cuisine, but exclude the field _id for all the documents in the collection restaurant.
db.restaurants.find({}, {"restaurant_id":1, "name":1,"borough":1 , "cuisine":1, "_id":0})

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Step 1 : Create abstract and concrete classes

//abstract class Pizza
public abstract class Pizza {
     
    public abstract void bakePizza(); 
}

//CheesePizza subclass
public class CheesePizza extends Pizza {

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 class Person {

    private final String firstName; // required
    private final int age;
    private final String phone;

     private Person(PersonBuilder builder) {
        this.firstName = builder.firstName;
        this.age = builder.age;
        this.phone = builder.phone;

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public interface PaymentStrategy {

	public void pay(int amount);
}


public class CreditCardStrategy implements PaymentStrategy {

	private String name;
	private String cardNumber;

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interface DatabaseExecuter {
  public void executeDatabase(String query);
}

class DatabaseExecuterImpl implements DatabaseExecuter {

  @Override
  public void executeDatabase(String query) {
    System.out.println("Going to execute Query: " + query);
  }

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class Singleton { 
  
  //static field
  private static Singleton object; 
    
  //private Construtor
  private Singleton() {} 
  
  //static method
  public static synchronized Singleton getInstance() 

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public class Triangle implements Polygon { 
  
    @Override
    public void calculateArea() { 
        // TODO  
    } 
}

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public class Rectangle implements Polygon { 
  
    @Override
    public void calculateArea() { 
        // TODO  
    } 
}

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public class Square implements Polygon { 
  
    @Override
    public void calculateArea()
    { 
        // TODO  
    } 
} 

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interface Polygon {
void calculateArea();
}