testconversion.java

疯狂Java讲义_源码(含Java设计模式CHM

/**
 * Description:
 * <br/>Copyright (C), 2005-2008, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee [e-mail]
 * @version  1.0
 */
public class TestConversion
{
	public static void main(String[] args) 
	{
		double d = 13.4;
		long l = (long)d;
		System.out.println(l);
		int in = 5;
		//下面代码编译时出错：试图把一个数值型变量转换为boolean型，
		//编译时候会提示: 不可转换的类型
		//boolean b = (boolean)in;
		Object obj = "Hello";
		//obj变量的编译类型为Object，是String类型的父类，可以强制类型转换
		//而且obj变量实际上类型也是String类型，所以运行时也可通过
		String objStr = (String)obj;
		System.out.println(objStr);
		//定义一个objPri变量，编译类型为Object，实际类型为Integer
		Object objPri = new Integer(5);
		//objPri变量的编译类型为Object，是String类型的父类，可以强制类型转换
		//而objPri变量实际上类型是Integer类型，所以下面代码运行时引发ClassCastException异常
		String str = (String)objPri;

	}
}