toytest1.java

JAVA编程思想第四版英文原版习题答案. pdf原版的

//typeinfo/toys/ToyTest1.java
// TIJ4 Chapter Typeinfo, Exercise 1, page 561
// In ToyTest.java, comment out Toy's default constructor and
// explain what happens.
package typeinfo.toys;
import static net.mindview.util.Print.*;

interface HasBatteries {}
interface Waterproof {}
interface Shoots {}

class Toy {
	// With default constructor commented out will be
	// unable to instantiate this Toy, super of FancyToy:
	// Toy() {}
	Toy(int i) {}
}

class FancyToy extends Toy 
	implements HasBatteries, Waterproof, Shoots {
		FancyToy() { super(1); }
}

public class ToyTest1 {
	static void printInfo(Class cc) {
		print("Class name: " + cc.getName() +
			" is interface? [" + cc.isInterface() + "]");
		print("Simple name: " + cc.getSimpleName());
		print("Canonical name: " + cc.getCanonicalName());
	}
	public static void main(String[] args) {
		Class c = null;
		try {
			c = Class.forName("typeinfo.toys.FancyToy");
		} catch(ClassNotFoundException e) {
			print("Can't find FancyToy");
			System.exit(1);
		}
		printInfo(c);
		for(Class face : c.getInterfaces())
			printInfo(face);
		Class up = c.getSuperclass();
		Object obj = null;
		try {
			// Requires default constructor in order to
			// create a super or Toy object:
			obj = up.newInstance();
		} catch(InstantiationException e) {
			print("Cannot instantiate");
			System.exit(1);
		} catch(IllegalAccessException i) {
			print("Cannot access");
			System.exit(1);
		}
		printInfo(obj.getClass());
	}
}