Generic Singleton Factory Pattern

Java

by techbard 2016. 7. 25. 20:37

# GenericSingletonFactory.java

public class GenericSingletonFactory {

private static applySame<Object> IDENTITY = new applySame<Object>() {

@Override
public Object apply(Object arg) {
return arg;
}
};

@SuppressWarnings("unchecked")
public static <T> applySame<T> identityFunction() {
return (applySame<T>) IDENTITY;
}

public static void main(String[] args) {

String[] strings = { "x", "y", "z" };
applySame<String> sameString = identityFunction();

for (String s : strings) {
System.out.println(sameString.apply(s));
}

Number[] numbers = {1, 2.0, 3L};
applySame<Number> sameNumber = identityFunction();

for (Number n : numbers) {
System.out.println(sameNumber.apply(n));
}
}
}

interface applySame<T> {
T apply(T arg);
}