randomlist6.java

JAVA编程思想第四版英文原版习题答案. pdf原版的

// generics/RandomList6.java
// TIJ4 Chapter Generics, Exercise 6, page 627
// Use RandomList with two more types in addition to the one shown in main().
import java.util.*;
import typeinfo.pets.*;

public class RandomList6<T> {
	private ArrayList<T> storage = new ArrayList<T>();
	private Random rand = new Random(47);
	public void add(T item) { storage.add(item); }
	public T select() {
		return storage.get(rand.nextInt(storage.size()));
	}
	public static void main(String[] args) {
		RandomList6<String> rs = new RandomList6<String>();
		for(String s : ("The quick brown fox jumped over " +
			"the lazy brown dog").split(" "))
			rs.add(s);
		for(int i = 0; i < 11; i++)
			System.out.print(rs.select() + " ");
		System.out.println();
		RandomList6<Integer> ri = new RandomList6<Integer>();
		for(int i = 0; i < 11; i++)
			ri.add(i); // autboxing
		for(int i = 0; i < 11; i++)
			System.out.print(ri.select() + " "); 
		System.out.println();
		RandomList6<Pet> rp = new RandomList6<Pet>();
		for(Pet p : Pets.arrayList(10))
			rp.add(p);
		for(int i = 0; i < 11; i++)
			System.out.print(rp.select() + " "); 	
	}
}