// patterns/Single.java

// (c)2021 MindView LLC: see Copyright.txt

// We make no guarantees that this code is fit for any purpose.

// Visit http://OnJava8.com for more book information.

@SuppressWarnings("unchecked")

public final class Single<T> {

private static Object single; // [1]

public Single(T val) {

if(single != null)

throw new RuntimeException(

"Attempt to reassign Single<" +

val.getClass().getSimpleName() + ">"

);

single = val;

}

public T get() { return (T)single; }

}