java - Write lock degradation problem in read-write lock

When the write lock is downgraded, the thread that has currently acquired the write lock is required to hold t...

From [Javadiscussion group] 2017-06-12 09:24:17 0  3  1269

java - Problem with separating verification code from front to back end

Premise: Suppose I have an interface for obtaining verification codes. It is under https://api.b.com/captcha. ...

From [Javadiscussion group] 2017-06-12 09:20:13 0  1  1267

java - spring security自定义filter的问题

用spring boot建的项目。现在想自定义一个filter，要求实现用户名，密码，公司id一起验证。下面是我的代码，参考UsernamePasswordAuthenticationFilter写的。 {代码...} ...

From [Javadiscussion group] 2017-04-17 15:31:30 0  4  1267

为什么java不要在foreach循环里进行元素的remove/add操作

选自《阿里巴巴JAVA开发手册》 图1代码执行情况是：解释删除1这个元素不会报错，但是删除2这个元素报错了，这个情况如何解释？

From [Javadiscussion group] 2017-04-18 10:54:42 0  8  1264

java RandomAccessFile 覆盖数据

下面的一个测试程序来说明我的问题： {代码...} 怎么才能防止覆盖啊？

From [Javadiscussion group] 2017-04-17 14:22:26 0  1  1263

C语言:合法的长整型常数

C语言中合法的长整型常数是 A) 't' B) "A"C) 65D) A好糊涂啊，答案是A，为什么不是C呢？

From [Javadiscussion group] 2016-11-07 11:07:42 0  1  1260

java - error when creating multiple modules module in idea and referencing spring boot

{code...}

From [Javadiscussion group] 2017-07-05 10:26:15 0  1  1258

java - myeclipse 安装之后启动报错

1.系统环境： ubuntu12.04 jdk 1.8 2.安装完 myeclipse，但是启动不起来。 报错内容如下： Java HotSpot(TM) Server VM warning: ignoring opti...

From [Javadiscussion group] 2017-04-18 10:49:36 0  1  1258

java - hbase regionServer Cannot assign requested address

{代码...}

From [Javadiscussion group] 2017-04-18 09:03:19 0  0  1258

java.util.Arrays.sort()数组形参传递为啥能修改原始数组的内容？

如题java.util.Arrays.sort(int[] a)数组形参传递为啥能修改原始数组的内容？ {代码...}

From [Javadiscussion group] 2017-04-18 09:06:24 0  5  1257

java - timer.schedule方法必须等上一个任务执行完毕才能进行下一个任务吗？

timer.schedule方法必须等上一个任务执行完毕才能进行下一个任务吗？还是说如果上一个任务还没有执行结束，下一个任务也会启动。如果任务在执行过程中发生异常，是不是会结束本次任务的执行。等下一次执行时间一...

From [Javadiscussion group] 2017-04-18 09:13:33 0  2  1254

java - SSM framework, no error is reported in the console, but 404 is reported during page testing

web.xml <?xml version="1.0" encoding="UTF-8"?><web-app xmlns:xsi=&quo...

From [Javadiscussion group] 2017-05-27 17:40:22 0  3  1250

java - inputStream关闭了，还有必要关闭InputStreamReader和BufferedReader吗？

{代码...} 如上代码，在使用完以后需要每个都关闭吗？还是只要关闭is就行了

From [Javadiscussion group] 2017-04-18 09:30:18 0  3  1250

x=3 y=4 I don't understand

Why x<=y is true

From [Javadiscussion group] 2021-09-27 19:34:48 0  1  1249

Question: How to specify some attributes of the javaBean object and then convert it to a json string

There are many attributes in javabean, but in fact only some of the attributes need to be converted into json ...

From [Javadiscussion group] 2017-06-28 09:24:15 0  4  1245