// Example 130 from page 99

//

class Vehicle { }

class Car extends Vehicle { }

class Sedan extends Car { }

class Shop<T> {

private T thing;

public T buyFrom() {

return thing;

}

public void sellTo(T thing) {

this.thing = thing;

}

}

class Example130 {

@SuppressWarnings("unchecked") // The five b0.sellTo(...) calls

public static void main(String[] args) {

Object object = new Object();

Vehicle vehicle = new Vehicle();

Car car = new Car();

Sedan sedan = new Sedan();

Shop b0;

b0 = new Shop<Object>();

b0 = new Shop<Vehicle>();

b0 = new Shop<Car>();

b0 = new Shop<Sedan>();

Object o0 = b0.buyFrom();

// Vehicle v4 = b0.buyFrom(); // Illegal

// Car c4 = b0.buyFrom(); // Illegal

// Sedan s4 = b0.buyFrom(); // Illegal

b0.sellTo(object); // Legal, but run-time unchecked

b0.sellTo(vehicle); // Legal, but run-time unchecked

b0.sellTo(car); // Legal, but run-time unchecked

b0.sellTo(sedan); // Legal, but run-time unchecked

b0.sellTo(b0.buyFrom()); // Legal, but run-time unchecked

Shop<Car> b1;

// b1 = new Shop<Object>(); // Illegal

// b1 = new Shop<Vehicle>(); // Illegal

b1 = new Shop<Car>();

// b1 = new Shop<Sedan>(); // Illegal

Object o1 = b1.buyFrom();

Vehicle v1 = b1.buyFrom();

Car c1 = b1.buyFrom();

// Sedan s1 = b1.buyFrom(); // Illegal

// b1.sellTo(object); // Illegal

// b1.sellTo(vehicle); // Illegal

b1.sellTo(car);

b1.sellTo(sedan);

b1.sellTo(b1.buyFrom());

Shop<?> b2;

b2 = new Shop<Object>();

b2 = new Shop<Vehicle>();

b2 = new Shop<Car>();

b2 = new Shop<Sedan>();

Object o2 = b2.buyFrom();

// Vehicle v2 = b2.buyFrom(); // Illegal

// Car c2 = b2.buyFrom(); // Illegal

// Sedan s2 = b2.buyFrom(); // Illegal

// b2.sellTo(object); // Illegal

// b2.sellTo(vehicle); // Illegal

// b2.sellTo(car); // Illegal

// b2.sellTo(sedan); // Illegal

// b2.sellTo(b2.buyFrom()); // Illegal

Shop<? extends Car> b3;

// b3 = new Shop<Object>(); // Illegal

// b3 = new Shop<Vehicle>(); // Illegal

b3 = new Shop<Car>();

b3 = new Shop<Sedan>();

Object o3 = b3.buyFrom();

Vehicle v3 = b3.buyFrom();

Car c3 = b3.buyFrom();

// Sedan s3 = b3.buyFrom(); // Illegal

// b3.sellTo(object); // Illegal

// b3.sellTo(vehicle); // Illegal

// b3.sellTo(car); // Illegal

// b3.sellTo(sedan); // Illegal

// b3.sellTo(b3.buyFrom()); // Illegal

Shop<? super Car> b4;

b4 = new Shop<Object>();

b4 = new Shop<Vehicle>();

b4 = new Shop<Car>();

// b4 = new Shop<Sedan>(); // Illegal

Object o4 = b4.buyFrom();

// Vehicle v4 = b4.buyFrom(); // Illegal

// Car c4 = b4.buyFrom(); // Illegal

// Sedan s4 = b4.buyFrom(); // Illegal

// b4.sellTo(object); // Illegal

// b4.sellTo(vehicle); // Illegal

b4.sellTo(car);

b4.sellTo(sedan);

// b4.sellTo(b4.buyFrom()); // Illegal

// Shop<Object> b5 = new Shop<Car>(); // Illegal

Shop<Object> b5 = new Shop<Object>();

Object o5 = b5.buyFrom();

// Vehicle v4 = b5.buyFrom(); // Illegal

// Car c4 = b5.buyFrom(); // Illegal

// Sedan s4 = b5.buyFrom(); // Illegal

b5.sellTo(object);

b5.sellTo(vehicle);

b5.sellTo(car);

b5.sellTo(sedan);

b5.sellTo(b5.buyFrom());

}

}