1, Process&Threads Most implementations of the Java virtual machine run as a single process. Threads exist within a process — every process has at least one. Threads share the process's resources, including memory and open files. This makes for effic…

For every type of object, the Java virtual machine instantiates an immutable instance of java.lang.Class which provides methods to examine the runtime properties of the object including its members and type information. Class also provides the abilit…

除了Java collection class/interface外,方便的有Google guava的utility class: Lists/Sets/Maps/Queues, 用它们可以方便地创建List等object. List<String> list = Lists.newArrayList(); or Lists.newArrayList("1", "2"); ArrayList v.s. Vector: 两者都是implement了Lis…

Good about Java: friendly syntax, memory management[GC can collect unreferenced memory resources], object-oriented features, portability. Stack Stores method invocations, local variables(include object reference, but the object itself is still stored…

1.标识符      用于命名程序的对象,如方法名,变量名,规则是: a.大小写敏感 b.由英文字符,文字字符,美元符号,下划线和数字组成,但不能以数字开头 c.不能是关键字 2.%:求余运算符    23%-4 结果为3,注:余数的符号与除数保持一致 3.++i:先引用变量i,后再执行i+1赋值给i作为运算结果 i++:先执行i加1,然后再将结果赋值给i作为运算结果进行引用 4.数组的命名三种 a.int  intArray[ ]; intArray=new   int[5]; b.int  …

前几天发现tomcat提示 Could not initialize class sun.awt.X11GraphicsEnvironment  问题.以为不验证,就没太关注,今天发现,有同事提示了个bug,验证码刷不出来,查看日志,报了很多这个个错误.才意识到问题的严重. 网上找了找资料:共两种解决方案 1:http://love-love-l.blog.163.com/blog/static/21078304200908595214/ 2:http://tcrct.iteye.com/blo…

Learning Java the O'Reilly's Way (Part I) Java 技术可以说是越来越重要了,不但可以用在计算机上,甚至连电视等家电用品,行动电话.个人数字助理(PDA)等电子产品,以及智能卡都可以透过 Java 的技术来为人们创造更便利的生活.许多人因此对 Java 感兴趣,想好好学习 Java. 因为讲授 Java 课程的关系,这几年来,不少人问我:怎样才能学好 Java,我给他们的建议很简单 ---『多读 Java 的好书,可以有系统又轻易地获得许多高手的经验』.…

1.0.0 Summary Tittle:[Java]-NO.20.Exam.1.Java.1.001-[1z0-807] Style:EBook Series:Java Since:2017-10-22 End:.... Total Hours:... Degree Of Diffculty:2 Degree Of Mastery:2 Practical Level:2 Desired Goal:2 Archieve Goal:.... Gerneral Evaluation:... Writ…

tomcat工程中创建二维码失败.抛出异常Can't connect to X11 window server using 'localhost:10.0' as the value of th 因为在linux系统中,创建图形画布失败.linux系统图形控件未启动导致的. 解决方法: java启动参数中添加 -Djava.awt.headless=true / 编辑tomcat目录下的bin/catalina.sh文件, 类似: exec "$_RUNJDB" "$LOGG…

原文地址:http://blog.csdn.net/dream_broken/article/details/49759043 想了解下某个Java项目的运行时jvm的情况,可以使用一些监控工具,比如jdk的bin下就提供了很多工具. 比如,本地运行一个程序,让它死循环 while(true){ try { Thread.sleep(10*1000); } catch (Exception e) { } } 然后,点击启动jconsole.exe 可以发现,jconsole.exe可以连接本地,…