webnotes

) installed on the local machine is earlier than the version specified by the classid attribute, and the browser downloads and installs JRE in this URL. Codebase has the following format: Codebase = In this format, if the locally installed JRE version is not the version specified by classid, go to the specified URL for download and installation. Codebase = In this format, if the JRE version installed on the local machine is smaller than the one specified in classid, download JRE from the speci

supportReport_java_out_of_memory ("permgen space ");In general, oom is an inevitable phenomenon for a large system. The most important thing is to master the troubleshooting method once OOM occurs. In addition, as the memory becomes more and more popularAppropriate, cms gc is becoming more and more mature, with 64Bit operating system, enabling large memory is also an optional method, which can basically avoid memory problems, after all, writing a few lines of code in Java completely consumes a

Java extracts the time in the visita Environment 8 hours earlier than the correct system time, because our time zone is set to Beijing time (that is, GMT + 8) Use the followingCodeA problem occurs when the time is used: Calendar c = calendar. getinstance (); Dateformat df = new simpledateformat ("HH: mm: SS "); Return DF. Format (C. gettime ()); After the check, it is found that the default time zone set by Java is changed to id = "GMT", while the time zone in Beijing is GMT +

Javalangaccess to really execute object#finalize.Jla.invokefinalize (Finalizee);/ * Clear stack slot containing this variable, to decrease the chances of false retention with a cons Ervative GC * /Finalizee =NULL; } }Catch(Throwable x) { }Super. Clear (); }There is another way that we can debug at the Finalizerthread break point, so that we can verify our ideas. Alright, let's get here today, ^_^.Resources http://openjdk.java.net/jeps/132 Http://docs.oracle.com/javase/7/docs

private JRE, and the other one is called the public JRE. The private JRE is usually called internally by the JDK itself;Specific reference: http://javaconceptoftheday.com/jdk-installation/ is This from is installed inside JDK folder (C:\Program Files (x86) \java\jdk1. 7 is used by the tools like Javac etc.Refer to Oracle Website for more information: http://docs.oracle.com/javase/7/docs/webnotes/install/windows/jdk-installation-windows.html#priv

The problem is also very silent, yesterday reinstall Mac OS X, and then install the JDK, do not want to install JDK 8, and then start the experiment, the results are similar to the following exception:Org.aspectj.apache.bcel.classfile.ClassFormatException:File: ' Java.util.Comparator ': Invalid byte tag in constant Pool:18look, feel like the JDK version caused the problem, so you want to switch to JDK 7, here is a brief talk about how to uninstall the JDK in Mac OS X, as described here:http://do

time = Ms.Direct call using passed value:16 16 16) 31 15Average time = Ms.Call to object using member field:46 47 47) 47 32Average time = Ms.Call to object using passed value:15 16 31) 16 16Average time = Ms.Reflection Call using member field:812 782 844) 844 844Average time = 829 Ms.Reflection call using passed value:938 953 954) 1031 953Average time = 973 Ms.Java version 1.6.0_13Java HotSpot (TM) Client VMS11.3-b02Sun Microsystems INC.Direct Object Creation:62 47 78) 32 93Average time = Ms.Re

Environment Note: Prior to upgrading the MAC system is installed in Java 7 in the normal use of Eclipse, the upgrade can not be used after the purpose: Delete Java 7 back to the JAVA6 environment to reconfigure the Eclipse INSTALLJRE path Java packageThe operation is as follows:Switch to root permissions under Mac:topwqp:~ wangqiupeng$ Sudo-iPassword:topwqp:~ root# WhoAmIRoottopwqp:~ root#Delete Java 7 environment under Mac: Refer:http://docs.oracle.com/javase/7/docs/

Under the Windows platform developed accustomed to a variety of Ides, have to admit that the IDE to our development to bring convenience. So I hope to find a suitable IDE under the Linux platform. This reminds me that Eclipse has a cross-platform nature.Then start building the environment.1. First you need to download the package, because the operation of Eclipse requires the Java environment, need to go to the Oracle Web site download JDKHttp://www.oracle.com/technetwork/java/javase/downloads/i

versions (uname-a View System Version) 4.1.2 64-bit system download Linux x64((x64.rpmand x64.tar.gz) 4.2、install jdk(.tar.gz, 32-bit system as an example) Installation Method reference http://docs.oracle.com/javase/7/docs/webnotes/install/linux/linux-jdk.html 4.2.1 select the location where you want to install java, such as in the/usr/directory, and create a folder named java (mkdirjava) 4.2.2 move the jdk-7u40-linux-i586.tar.gz file to/usr/java 4.2

) Installation Method reference http://docs.oracle.com/javase/7/docs/webnotes/install/linux/linux-jdk.html 4.2.1 select the location where you want to install java, such as in the/usr/directory, and create a folder named java (mkdirjava) 4.2.2 move the jdk-7u40-linux-i586.tar.gz file to/usr/java 4.2.3 decompression: tar-zxvf jdk-7u40-linux-i586.tar.gz 4.2.4 Delete jdk-7u40-linux-i586.tar.gz (to save space) Now, after jkd is installed, configure

, manufacturing date, manufacturer, and other miscellaneous. D. query the list of files contained in the specified installed software package. Syntax: rpm-QL [RPM package name] E. Dependency requirements for querying software packages Syntax: rpm-QR [RPM package name] F. Specify the software package to which the file belongs in the query system. Syntax: rpm-QF [file name] JDK 7 installation for Linux platforms Http://docs.oracle.com/javase/7/docs/webnotes