在 Windows 64 上以 32 位模式运行 java

Question

I need to run java in 32 bit mode under windows 8.1 64 bit.

I have installed java 7 jre under c:\\Program Files\\Java\\jre7 (64bit JVM) and under c:\\Program Files (x86)\\Java\\jre7 (32bit JVM).

However, if from cmd I issue java -d32 -version , I get this error:

Error: This Java instance does not support a 32-bit JVM.
Please install the desired version.

Without the -d32 switch it confirms its running the 64 bit JVM:

Java(TM) SE Runtime Environment (build 1.7.0_51-b13)
Java HotSpot(TM) 64-Bit Server VM (build 24.51-b03, mixed mode)

So I opened the java control panel and added the 32bit JVM to the user installed JRE (system tab does not allow me to change anything even if running as administrator), but nothing changes.

I've read some posts of users saying that with java 7+ the -d32 mode should be supported but I can't get it.

Note: Please note that I cannot remove the 64bit JVM because I need it for other applications

Answer 1

According to this FAQ :

How do I select between 32 and 64-bit operation? What's the default?

The options -d32 and -d64 have been added to the Java launcher to specify whether the program is to be run in a 32 or 64-bit environment. On Solaris these correspond to the ILP32 and LP64 data models, respectively. Since Solaris has both a 32 and 64-bit J2SE implementation contained within the same installation of Java, you can specify either version. If neither -d32 nor -d64 is specified, the default is to run in a 32-bit environment. Other Java commands (javac, javadoc, etc.) will rarely need to be executed in a 64-bit environment. However, the -d32/-d64 options may be passed to these commands and then on to the Java launcher using the established -J prefix option (eg: -J-d64).
All other platforms (Windows and Linux) contain separate 32 and 64-bit installation packages. If both packages are installed on a system, you select one or the other by adding the appropriate "bin" directory to your path. For consistency, the Java implementations on Linux accept the -d64 option.

Answer 2

I've found another solution to that. By using launchj4 I can wrap my jar into an exe and I can specify the JRE I want to use and force it to search for a 32bit JVM, set min and max version etc (see the JRE). The wrapper will automatically search installed JRE's and chose the one that meets the requirements.

Also wrapping my jar into an exe is more convenient for deploying my application.

Answer 3

You can have both 32bit and 64 bit installed on the same machine. Infact you can have multiple version of each of 32bit and 64bit installed (eg - java6 and java7). Because each JRE will be installed in different folders, it usually does not matter.

When running different versions of jre, your application will search for the Java executable using the PATH variable. So if Java 32bit is first on the PATH, you will have problems running a Java 64bit application. You can modify the path to use a certain Java version eg by defining a environment variable JAVA32HOME with the value C:\\java\\java6 (32bit) and change the command to

%JAVA32HOME%\\bin\\java ...

Or you can manually add the version you want to use, first in the PATH variable. Remember the first instance of java.exe found while searching your PATH will be the one that is executed.

Answer 4

Why don't you just install the 32-bit version of Java as well from the link below:

Java Downloads for All Operating Systems

Answer 5

Consider going to your settings , choosing your active profile then click on advanced settings , now on the menu that pops up and choose the version you would like to work with . Once everything is configured use the terminal to verify the usage of the right version. Now incaqse thus pdate-alternatives --config java. through the terminal and update any values by selecting the version you like and pressing down on the enter key on the output you get