// The MIT License (MIT)

//

// Copyright (c) 2018 Robert C. Seacord

//

// Permission is hereby granted, free of charge, to any person obtaining a copy

// of this software and associated documentation files (the "Software"), to deal

// in the Software without restriction, including without limitation the rights

// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

// copies of the Software, and to permit persons to whom the Software is

// furnished to do so, subject to the following conditions:

//

// The above copyright notice and this permission notice shall be included in all

// copies or substantial portions of the Software.

//

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

// SOFTWARE.

package OBJ03J;

import java.util.ArrayList;

import java.util.List;

/**

* Generic version of the Box class.

* @param <T> the type of the value being boxed

*/

// @SuppressWarnings("unchecked")

class Box<T> {

// T stands for "Type"

private T t;

void set(T t) { this.t = t; }

public T get() { return t; }

public static void main(String[] args) {

// invocation of the set method is allowed if the argument is compatible with Number

Box<Number> box = new Box<>();

Integer i = 10;

Double d = 10.1;

box.set(i); // OK

box.set(d); // OK

Box<Integer> intBox = new Box<>();

intBox.set(1);

// If the actual type argument is omitted, a raw type of Box<T> is created:

Box rawBox;

// For backward compatibility, assigning a parameterized type to its raw type is allowed:

Box<String> stringBox = new Box<>();

rawBox = stringBox; // OK

rawBox.set(8); // warning: unchecked invocation to set(T)

// The "unchecked" warning is disabled, by default, though the compiler gives a hint.

// To see all "unchecked" warnings, recompile with -Xlint:unchecked.

// Assigning a raw type to a parameterized type, creates a warning:

rawBox = new Box(); // rawBox is a raw type of Box<T>

intBox = rawBox; // warning: unchecked conversion

List<String> ls = (List) new ArrayList(); // warning: unchecked conversion

if (intBox.getClass() == stringBox.getClass()) {

System.out.println("intBox.getClass() == stringBox.getClass()");

}

}

}