对象数组报错“空指针”:Exception in thread "main" java.lang.NullPointerException
来源:互联网 发布:ubuntu apache php 编辑:程序博客网 时间:2024/06/16 13:21
Student[] student = new Student[4]; /*
这里虽然创建了对象数组,大小为4,但并没有为每个对象分配空间,即每个对象都是为空的。
所以如果使用student[0].age=18;
就会报空指针的错误,因为student[0]为空,即不存在这个学生,那你还问他的年龄,肯定会报错嘛。/*
所以先要把对象一个一个的初始化:
for(i=0;i<4;i++){
student[0]=new Student();
}
Exception in thread "main" java.lang.NullPointerException:
所谓空指针错误是,你叫某个人去做一件事,但这个人并不存在,所以没人干这个事情,那这事就会出差错。
0 0
- 对象数组报错“空指针”:Exception in thread "main" java.lang.NullPointerException
- JAVA类对象的数组报错Exception in thread "main" java.lang.NullPointerException
- Exception in thread "main" java.lang.NullPointerException java报空指针异常
- Exception in thread "main" java.lang.NullPointerException
- Exception in thread "main" java.lang.NullPointerException
- Java报错异常-----Exception in thread "main" java.lang.NullPointerException
- Exception in thread "main" java.lang.NullPointerException问题
- hdfs下载出现Exception in thread "main" java.lang.NullPointerException
- 20170204Exception in thread "main" java.lang.NullPointerException
- Hive启动报错:Exception in thread "main" java.lang.RuntimeException: java.lang.RuntimeException: java.io.
- String报错Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
- Exception in thread "main" java.lang.NullPointerException at java.lang.ProcessBuilder.start(
- Exception in Thread "HouseKeeper" java.lang.NullPointerException
- Exception in thread "HouseKeeper" java.lang.NullPointerException
- Exception in thread "HouseKeeper" java.lang.NullPointerException
- Exception in thread "HouseKeeper" java.lang.NullPointerException
- Exception in Thread "HouseKeeper" Java.lang.NullPointerException
- 请教关于JAVA异常问题Exception in thread "main" java.lang.NullPointerException
- 游戏开发工具
- paip.自适应网页设计 跟 响应式 设计的区别跟原理and实践总结
- Light OJ 1109 - False Ordering
- Android Activity类详解
- String构造器中originalValue.length>size 发生的情况
- 对象数组报错“空指针”:Exception in thread "main" java.lang.NullPointerException
- UVa 10205 Stack 'em Up
- CRichEditCtrl相关应用技巧收集
- ExtJS4 动态生成的grid导出为excel(纯前台)
- 机器学习(ML)中文视频教程
- ubuntu下安装oracle java8
- Light OJ 1045 Digits of Factorial(求位数)
- 算法的力量
- centOS下安装apache2.2