Java in your current path

Содержание

Ошибка при запуске Eclipse
How to Add Java to Your System Path
Requirements:
Procedure:
Windows
Linux
PATH and CLASSPATH
Update the PATH Environment Variable (Microsoft Windows)
Update the PATH Variable (Solaris and Linux)
Checking the CLASSPATH variable (All platforms)
Ошибка при запуске Eclipse

Ошибка при запуске Eclipse

Наверняка многие из вас сталкивались с ошибкой запуска Eclipse:

A Java Runtime Environment (JRE) or Java Development Kit (JDK) must be available in order to run Eclipse. No Java virtual machine was found after searching the following locations: C:\Program Files(x86)\Eclipse Classic 4.2.2\jre\bin\javaw.exe javaw.exe in your current PATH

Эта ошибка говорит нам о том, что Eclipse не может найти путь к Java Runtime Environment или Java Development Kit. Сейчас я вам расскажу причины возникновения такой ошибки и способы ее устранения.

В Интернете многие советуют добавить путь к файлу javaw.exe в переменную окружения Path, но этого не стоит делать. Нет, не потому что можно что-либо сломать, а потому что появится другая ошибка:

Failed to load JNI shared library «Program Files (x86)\Java\jdk1.6.0_20\jre\bin\client\jvm.dll»

Дело в том, что для работы Eclipse требуется виртуальная машина и внимание: именно той разрядности (x86 или x64), которую имеет установленная версия Eclipse. Другими словами, если у вас установлен Eclipse для платформы x86, то для запуска этой IDE требуется наличие установленной виртуальной машины для платформы x86.

Итак, когда вы определились с разрядностью Eclipse, вам нужно скачать виртуальную машину. Для этого, зайдите на сайт www.java.com/en/ и вверху страницы вибираем ссылку «Download», затем на открывшейся странице жмем ссылку «See all Java downloads» и скачиваем Java именно той разрядности, какой разрядности у вас Eclipse.

Если вы все сделали правильно, после установки Java, Eclipse запустится без каких-либо ошибок.

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How to Add Java to Your System Path

Having Java installed on your system enables you to run and possibly compile Java programs. If your system does not know where to look for it, however, you will not be able to use these features as simply.

Requirements:

Java JDK installed on Windows or Linux.

Procedure:

Windows

Once Java is installed, locate the installation directory, such as:

C:\Program Files\Java\jdk1.7.0_21

Next, we have to add the sub-directory \bin to the system’s environment variables. Right-click My Computer, then click Properties, then Advanced System Settings, then Environment Variables. Go to the Path system variable entry, and press Edit. You may see a rather long list here. At the very end, add the following:

C:\Program Files\Java\jdk1.7.0_21\bin

If this is not the location of the \bin directory in your Java installation directory, you may change it to your actual path. Press OK. Next, look for the JAVA_HOME system variable in the same Environment Variables list. If it is not there, press New. Name the variable JAVA_HOME, and as the variable value, add:

C: \Program Files\Java\jdk1.7.0_21

This is the Java installation directory. Again, if this is not correct, you will need to use the appropriate path. Press OK. Now, from a command line, type one of the following:

At this point, you should see the help information for both commands, instead of:

‘java’ is not recognized as an internal or external command, operable program or batch file.

Linux

Upon gaining access to the command line interface (CLI), locate the installation directory of Java. Once this is done, type the following:

Then, once the .bashrc configuration file is open, press i

This will bring you into insert mode. Once you are in it, move the arrows around until you get to the end of the file. Then, type the following:

PATH=$PATH:/path/to/Java/installation/bin JAVA_HOME=/path/to/java/jre/bin export PATH export JAVA_HOME

The first directory should be the path to the bin directory in the jdk. The second path should be the bin directory in the jre. Then, type the “escape” button, followed by:

Upon restart, you will have Java in your path, set by your environment variables.

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PATH and CLASSPATH

This section explains how to use the PATH and CLASSPATH environment variables on Microsoft Windows, Solaris, and Linux. Consult the installation instructions included with your installation of the Java Development Kit (JDK) software bundle for current information.

After installing the software, the JDK directory will have the structure shown below.

The bin directory contains both the compiler and the launcher.

Update the PATH Environment Variable (Microsoft Windows)

You can run Java applications just fine without setting the PATH environment variable. Or, you can optionally set it as a convenience.

Set the PATH environment variable if you want to be able to conveniently run the executables ( javac.exe , java.exe , javadoc.exe , and so on) from any directory without having to type the full path of the command. If you do not set the PATH variable, you need to specify the full path to the executable every time you run it, such as:

C:\Java\jdk1.7.0\bin\javac MyClass.java

The PATH environment variable is a series of directories separated by semicolons ( ; ). Microsoft Windows looks for programs in the PATH directories in order, from left to right. You should have only one bin directory for the JDK in the path at a time (those following the first are ignored), so if one is already present, you can update that particular entry.

The following is an example of a PATH environment variable:

C:\Java\jdk1.7.0\bin;C:\Windows\System32\;C:\Windows\;C:\Windows\System32\Wbem

It is useful to set the PATH environment variable permanently so it will persist after rebooting. To make a permanent change to the PATH variable, use the System icon in the Control Panel. The precise procedure varies depending on the version of Windows:

Select Start, select Control Panel. double click System, and select the Advanced tab.
Click Environment Variables. In the section System Variables, find the PATH environment variable and select it. Click Edit. If the PATH environment variable does not exist, click New .
In the Edit System Variable (or New System Variable) window, specify the value of the PATH environment variable. Click OK. Close all remaining windows by clicking OK.

From the desktop, right click the My Computer icon.
Choose Properties from the context menu.
Click the Advanced tab (Advanced system settings link in Vista).
Click Environment Variables. In the section System Variables, find the PATH environment variable and select it. Click Edit. If the PATH environment variable does not exist, click New .
In the Edit System Variable (or New System Variable) window, specify the value of the PATH environment variable. Click OK. Close all remaining windows by clicking OK.

From the desktop, right click the Computer icon.
Choose Properties from the context menu.
Click the Advanced system settings link.
Click Environment Variables. In the section System Variables, find the PATH environment variable and select it. Click Edit. If the PATH environment variable does not exist, click New .
In the Edit System Variable (or New System Variable) window, specify the value of the PATH environment variable. Click OK. Close all remaining windows by clicking OK.

Note: You may see a PATH environment variable similar to the following when editing it from the Control Panel:

%JAVA_HOME%\bin;%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem

Variables enclosed in percentage signs ( % ) are existing environment variables. If one of these variables is listed in the Environment Variables window from the Control Panel (such as JAVA_HOME ), then you can edit its value. If it does not appear, then it is a special environment variable that the operating system has defined. For example, SystemRoot is the location of the Microsoft Windows system folder. To obtain the value of a environment variable, enter the following at a command prompt. (This example obtains the value of the SystemRoot environment variable):

Update the PATH Variable (Solaris and Linux)

You can run the JDK just fine without setting the PATH variable, or you can optionally set it as a convenience. However, you should set the path variable if you want to be able to run the executables ( javac , java , javadoc , and so on) from any directory without having to type the full path of the command. If you do not set the PATH variable, you need to specify the full path to the executable every time you run it, such as:

% /usr/local/jdk1.7.0/bin/javac MyClass.java

To find out if the path is properly set, execute:

This will print the version of the java tool, if it can find it. If the version is old or you get the error java: Command not found, then the path is not properly set.

To set the path permanently, set the path in your startup file.

For C shell ( csh ), edit the startup file (~/.cshrc ):

set path=(/usr/local/jdk1.7.0/bin $path)

For bash , edit the startup file ( ~/.bashrc ):

PATH=/usr/local/jdk1.7.0/bin:$PATH export PATH

For ksh , the startup file is named by the environment variable, ENV . To set the path:

PATH=/usr/local/jdk1.7.0/bin:$PATH export PATH

For sh , edit the profile file ( ~/.profile ):

PATH=/usr/local/jdk1.7.0/bin:$PATH export PATH

Then load the startup file and verify that the path is set by repeating the java command:

% source ~/.cshrc % java -version

Checking the CLASSPATH variable (All platforms)

The CLASSPATH variable is one way to tell applications, including the JDK tools, where to look for user classes. (Classes that are part of the JRE, JDK platform, and extensions should be defined through other means, such as the bootstrap class path or the extensions directory.)

The preferred way to specify the class path is by using the -cp command line switch. This allows the CLASSPATH to be set individually for each application without affecting other applications. Setting the CLASSPATH can be tricky and should be performed with care.

The default value of the class path is «.», meaning that only the current directory is searched. Specifying either the CLASSPATH variable or the -cp command line switch overrides this value.

To check whether CLASSPATH is set on Microsoft Windows NT/2000/XP, execute the following:

On Solaris or Linux, execute the following:

If CLASSPATH is not set you will get a CLASSPATH: Undefined variable error (Solaris or Linux) or simply %CLASSPATH% (Microsoft Windows NT/2000/XP).

To modify the CLASSPATH , use the same procedure you used for the PATH variable.

Class path wildcards allow you to include an entire directory of .jar files in the class path without explicitly naming them individually. For more information, including an explanation of class path wildcards, and a detailed description on how to clean up the CLASSPATH environment variable, see the Setting the Class Path technical note.

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Источник

Ошибка при запуске Eclipse

Наверняка многие из вас сталкивались с ошибкой запуска Eclipse:

Failed to load JNI shared library «Program Files (x86)\Java\jdk1.6.0_20\jre\bin\client\jvm.dll»

Если вы все сделали правильно, после установки Java, Eclipse запустится без каких-либо ошибок.

Источник