[java]1、Long对象与long基本类型

对象转化时，如果对象为null，会报异常，longValue() 方法、toString()方法、intValue()方法

public class TimeMillsTest {    public static void main(String[] args) {//      long currentTimeMillis=System.currentTimeMillis()/1000;//      System.out.println("now="+currentTimeMillis);         Long a=10L;         Long b=20L;         Long d=null;         long e=100;         boolean c;         if(a>0){             c=!(a>0);             System.out.println("a>0 = "+c);         }         if(d==null){             System.out.println("sss");         }         if(e>a){             c=(a>0);             System.out.println("d==="+c);         }         if(d.longValue()>0){//nullpoint异常             System.out.println("you can't see me");         }    }}