containercomparison.java

这是Thinking in Java最新版第4版的源代码

package chapter16;
import java.util.*;
class BerylliumSphere{
	private static long counter;
	private final long id=counter++;
	public String toString(){
		return "Sphere "+id;
	}
}
public class ContainerComparison {
	public static void main(String args[]){
		BerylliumSphere[] spheres=new BerylliumSphere[10];
		/*
		 * 上面的语句说明Java可以现时实例化多个对象
		 */
		for(int i=0;i<5;i++){
			spheres[i]=new BerylliumSphere();
			/*
			 * 每实例化开一次，c
			 * 
			 * ounter++运行一次
			 */
		}
		System.out.println(Arrays.toString(spheres));
		/*
		 * Arrays.toString（）是java的一个方法，不过，可以自己写toString方法，这样，
		 * 本程序的结果不是
		 * [chapter16.BerylliumSphere@1fb8ee3, chapter16.BerylliumSphere@61de33, chapter16.BerylliumSphere@14318bb, chapter16.BerylliumSphere@ca0b6, chapter16.BerylliumSphere@10b30a7, null, null, null, null, null]
chapter16.BerylliumSphere@10b30a7
		而是
		[Sphere 0, Sphere 1, Sphere 2, Sphere 3, Sphere 4, null, null, null, null, null]
Sphere 4

		 */
		System.out.println(spheres[4]);
		
	}
}