ex34.java

来自「Thinking In Java 第四版练习题答案」· Java 代码 · 共 31 行

// generics/Ex34.java
// TIJ4 Chapter Generics, Exercise 34, page 709
/* Create a self-bounded generic type that contains an abstract method
* that takes an argument of the generic type parameter and produces a
* return value of the generic type parameter. In a non-abstract method
* of the class, call the abstract method and return its result. Inherit
* from the self-bounded type and test the resulting class.
*/

abstract class SelfBoundedType<T extends SelfBoundedType<T>> {
	abstract T f(T arg);
	T g(T arg) { 
		System.out.println("g(T arg)");
		return f(arg); 
	}	
}

class D extends SelfBoundedType<D> {
	D f(D arg) { 
		System.out.println("f(D arg)");
		return arg; 
	}	
}


public class Ex34 {
	public static void main(String[] args) {
		D d = new D();
		d.f(d).g(d);
	}
}