Eclipse将在默认情况下尝试使用默认的“java.exe”(由PATH引用的第一个)启动。

要记住三件事:

"Installing" a JRE or a JDK can be as simple as unzipping or copying it from another computer: there is no special installation steps, and you can have as many different JVM versions (1.4, 5.0, 6.0...) as you want, "installed" (copied) almost anywhere on your disk. I would recommend to always run Eclipse with the lastest JRE possible (to benefit from the latest hotspot evolutions). You can: Reference that exact JRE path in your eclipse.ini. Copy any JRE of your in your <eclipse>/jre directory. In both cases, no PATH to update. The JVM you will reference within your Eclipse session is not always the one used for launching Eclipse because: You only need a JRE to launch Eclipse, but once Eclipse launched, you should register a JDK for your projects (especially for Java sources and debugging purposes, also in theory for compilation but Eclipse has its own Java compiler) Note: You could register just a JRE within Eclipse because it is enough to run your program, but again a JDK will allow for more operations. Even though the default registered Java in Eclipse is the one used to launch the session, you can want to register an older SDK (including a non-Sun one) in order to run/debug your programs with a JRE similar to the one which will actually be used in production.

2012年6月，jmbertucci评论道:

我运行的是64位的Windows 7，并且安装了32位的JRE。 我下载了一个64位的Eclipse 64位JRE。 因为我没有64位JRE，所以它抛出了错误，这是有道理的。 我转到Java手动安装页面(不像你想的那样直接访问)，安装了64位版本。参见“适用于所有操作系统的Java下载”。 这就是我所需要的。

2016年4月:史蒂夫·梅恩在评论中补充道:

我必须编辑eclipse.ini文件以引用正确的Java路径- 当Eclipse .ini中有值时，Eclipse根本不使用环境PATH。

我也遇到过这个问题。我的案例如下:

在文本:

HKEY_CURRENT_USER\Environment
    Path    REG_SZ    %JAVA_HOME%\bin;C:\ProgramFiles\nodejs

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment
    JAVA_HOME    REG_SZ    C:\ProgramFiles\Java\jdk
    Path    REG_EXPAND_SZ    C:\bin;%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;%SYSTEMROOT%\System32\
WindowsPowerShell\v1.0\;C:\Program Files\Intel\DMIX;c:\Program Files (x86)\Microsoft SQL Server\90\Tools\binn\;C:\Progra
m Files (x86)\Perforce;C:\ProgramFiles\010 Editor;C:\Program Files\Microsoft SQL Server\130\Tools\Binn\;C:\ProgramFiles\
Git\cmd;C:\Program Files (x86)\Skype\Phone\

C:\Users\ssfang> echo %^JAVA_HOME% = "%^JAVA_HOME%" = %%JAVA_HOME%% %JAVA_HOME%
%JAVA_HOME% = "%^JAVA_HOME%" = %C:\ProgramFiles\Java\jdk% C:\ProgramFiles\Java\jdk

我发现他们的注册表值Path的类型是不同的，所以我用下面的命令检查路径是否有效:

C:\Users\ssfang> where node java
C:\ProgramFiles\nodejs\node.exe
INFO: Could not find "java".

因此，我通过以下命令(Setx)重置本地(当前用户)环境:

C:\Users\ssfang> setx PATH %^JAVA_HOME%\bin;"C:\ProgramFiles\nodejs"

SUCCESS: Specified value was saved.

C:\Users\ssfang> reg query HKEY_CURRENT_USER\Environment /v Path

HKEY_CURRENT_USER\Environment
    Path    REG_EXPAND_SZ    %JAVA_HOME%\bin;C:\ProgramFiles\nodejs

C:\Users\ssfang> where node java
C:\ProgramFiles\nodejs\node.exe
INFO: Could not find "java".

C:\Users\ssfang>echo %PATH%
C:\bin;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Fi
les\Intel\DMIX;c:\Program Files (x86)\Microsoft SQL Server\90\Tools\binn\;C:\Program Files (x86)\Perforce;C:\ProgramFile
s\010 Editor;C:\Program Files\Microsoft SQL Server\130\Tools\Binn\;C:\ProgramFiles\Git\cmd;C:\Program Files (x86)\Skype\
Phone\;%JAVA_HOME%\bin;C:\ProgramFiles\nodejs

但是，在当前流程中，它不能将这些更改传播到其他正在运行的流程。

但是，如果直接在“注册表编辑器”中修改用户环境变量，

those modifications to the environment variables do not result in immediate change. For example, if you start another Command Prompt after making the changes, the environment variables will reflect the previous (not the current) values. The changes do not take effect until you log off and then log back on. To effect these changes without having to log off, broadcast a WM_SETTINGCHANGE message to all windows in the system, so that any interested applications (such as Windows Explorer, Program Manager, Task Manager, Control Panel, and so forth) can perform an update.

详细信息请参见如何将环境变量传播到系统

在这里，我给出了一个powershell脚本来完成它:

# powershell -ExecutionPolicy ByPass -File
# Standard, inline approach: (i.e. behaviour you'd get when using & in Linux)
# START /B CMD /C CALL "foo.bat" [args [...]]
# powershell -ExecutionPolicy ByPass -WindowStyle Hidden -File myScript.ps1 


<#
Add-Type @'

public class CSharp
{
    public static void Method(object[] first, object[] second)
    {
        System.Console.WriteLine("Hello world");
    }
}
'@
$a = 1..4;
[string[]]$b = "a","b","c","d";
[CSharp]::Method($a, $b);
#>


<#

#http://stackoverflow.com/questions/16552801/how-do-i-conditionally-add-a-class-with-add-type-typedefinition-if-it-isnt-add

#Problem Add-Type : Cannot add type. The type name 'PInvoke.User32' already exists.

if (-not ("MyClass" -as [type])) {
    add-type @"
    public class MyClass { }
"@
}


p.s. there's no Remove-Type; see this answer for more on how to best work around this limitation:
http://stackoverflow.com/questions/3369662/can-you-remove-an-add-ed-type-in-powershell-again

I think it will be wanted when debugging.
It is much simpler to close a tab in Console and open new one in PowerShell_ISE.exe or close PowerShell.exe.

Or

Start-Job -ScriptBlock {
    param([uri]$url,$OutputDir)
    # download and save pages
    Invoke-RestMethod $url | Out-File "$OutputDir\$($url.Segments[-1])" -Force
} -ArgumentList $link,$OutputDir

#>
if (-not ([System.Management.Automation.PSTypeName]'PInvoke.Program').Type)
{
    $sig=@"
using System;
using System.Runtime.InteropServices;
using System.Text;
using System.Collections.Generic;

// The global namespace is the "root" namespace: global::system will always refer to the .NET Framework namespace System.

///P/Invoke (Platform Invoke)
namespace PInvoke
{
    public static class User32
    {
        /// http://www.pinvoke.net/default.aspx/Constants/HWND.html
        // public const IntPtr HWND_BROADCAST = new IntPtr(0xffff);
        /// https://msdn.microsoft.com/en-us/library/windows/desktop/ms725497(v=vs.85).aspx
        /// http://www.pinvoke.net/default.aspx/Constants/WM.html
        public const UInt32 WM_SETTINGCHANGE = 0x001A;

        // SendMessageTimeout(HWND_BROADCAST, WM_SETTINGCHANGE, 0,    (LPARAM) "Environment", SMTO_ABORTIFHUNG,    5000, &dwReturnValue);

        /// https://msdn.microsoft.com/en-us/library/windows/desktop/ms644952(v=vs.85).aspx
        /// If the function succeeds, the return value is nonzero. 
        [System.Runtime.InteropServices.DllImport("user32.dll", EntryPoint = "SendMessageTimeout", SetLastError = true)]
        public static extern uint SendMessageTimeout(IntPtr hWnd, uint Msg, int wParam, string lParam, SendMessageTimeoutFlags fuFlags, uint uTimeout, out int lpdwResult);
    }

    [Flags]
    public enum SendMessageTimeoutFlags : uint
    {
        SMTO_NORMAL = 0x0,
        SMTO_BLOCK = 0x1,
        SMTO_ABORTIFHUNG = 0x2,
        SMTO_NOTIMEOUTIFNOTHUNG = 0x8,
        SMTO_ERRORONEXIT = 0x20
    }

    public class Program
    {
        public static void Main(string[] args)
        {
            //int innerPinvokeResult;
            //uint pinvokeResult = User32.SendMessageTimeout(User32.HWND_BROADCAST, User32.WM_SETTINGCHANGE, 0, "Environment", SendMessageTimeoutFlags.SMTO_NORMAL, 1000, out innerPinvokeResult);
            Console.WriteLine("Over!!!!!!!!!!!!!!!!!!!!!!!!!");
        }
    }
}
"@

    Add-Type -TypeDefinition $sig
}


## [PInvoke.Program]::Main([IntPtr]::Zero);

$innerPinvokeResult=[int]0
[PInvoke.User32]::SendMessageTimeout([IntPtr]0xffff, [PInvoke.User32]::WM_SETTINGCHANGE, 0, "Environment", [PInvoke.SendMessageTimeoutFlags]::SMTO_NORMAL, 1000, [ref]$innerPinvokeResult);

对于Setx Setx [/s [/u [] [/p]]]]] [/m]

/m Specifies to set the variable in the system environment. The default setting is the local environment

JDK不会在默认路径下安装JVM。

除非您像ant一样需要外部工具来运行，否则非jdk就足以让Eclipse运行。安装这样的JVM最简单的方法是访问http://java.com，让它安装它想安装的任何东西。

然后再次双击Eclipse二进制文件。

如果你下载了64位版本的Eclipse;它会查找64位版本的JRE。 如果你下载了32位版本的Eclipse;它会查找32位版本的JRE

我所做的就是同时安装32位和64位版本的JRE。你可以从SUN Oracle网站上得到。JAVA站点似乎会自动安装32位版本的JAVA。我想这是因为网络浏览器。

只需下载Java运行时环境(JRE)。这对我很管用!

一个问题是eclipse -64位版本和我们的Java安装为32位版本之间的冲突。这个问题不容易解决，因为Java安装页面没有提供64位的选项——它假设是32位，然后下载并安装32位的版本。要解决此问题，请遵循以下步骤:

通过转到Java SE运行时环境7下载64bit版本(此链接为我们提供了下载64bit版本Java的选项)。下载并安装。 现在，尝试安装Eclipse仍然会抛出一个错误。因此，我们从C:/program files/Java/复制jre7文件夹，并将其复制到Eclipse安装文件夹中。 现在，我们将其重命名为jre。

安装Eclipse。

——launcher.appendVmargs 虚拟机 C:\Program Files\Java\ jdk1.7.0_79 \ jre \ bin \ javaw.exe —vmargs