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JRE
From Qedoc
| This article is primarily for software developers and may contain sections which are of an advanced or highly technical nature. Do not panic. Normal users do not need to understand anything written here. |
The JRE (or Java Runtime Environment) is a requirement for running the Qedoc software.
A copy of the recommended minimum version of the JRE is included in the Qedoc software installation packages. It will normally install together with the Qedoc software, although the installation of the JRE can be cancelled. Most users should not worry themselves at all about the JRE. Just install the distribution packages. They should work straight away. If they don't, please tell us, and give details about the operating system you are using.
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JRE 5
Up to version 1.4.0, Qedoc required and included JRE 5. Without JRE 5, it will not start.
In version 1.4.4 we decided that JRE 6 added nothing of significance and didn't install as nicely. So we moved back to JRE 5. Comment is invited on the talk page.
JRE 6
In version 1.4.1, JRE 6 was bundled for the first time. From 1.4.2, it became a requirement to use JRE 6 and version 1.4.2 does not start without JRE 6. Version 1.4.2 makes minor use of JRE 6 features.
The following advantages and disadvantages are associated with JRE 6.
- JRE 6 is slightly smaller than JRE 5.
- The JRE 6 install doesn't detect previous JRE 6 installations and needs to be manually cancelled if JRE 6 is already installed.
- The use of JRE 6 seems to prevent the Qedoc sound system from working on Windows 98 SE.
User questions about the JRE
- "When the new JRE is installed, why doesn't it uninstall the old JRE? I don't want to have more than one on my computer."
- This is really an issue for Sun Microsystems (who make java). The reason is that they have always adopted a multiple concurrent versions policy. There is some sense behind this. Theoretically there can be java software which requires older versions and doesn't work with newer ones. Common installation programmes for java executables allow specification of both minimum and maximum versions.
- However you can ask Windows to uninstall older versions if they are cluttering up your system. Typically you can do this by choosing the java option in the Windows control panel.
- "Any particular platform becomes obsolete and unusable when the next version is issued. Sun Java (any version ) when installed stops use of any version previously installed. The last installed version is the primary driver. "
- It is true that the default java version after a new installation is the latest one installed. However it is possible to choose any of the versions on a machine to act as the default, and it is also possible to force most java software to look for and use whichever version it prefers.
- It is not true that any old versions on the machine become unusable - they are fully usable. In this sense, java differs from other software plug-ins such as flash and pdf (from Adobe), because switching between versions is easily controlled both by human users and individual software applications. Java offers very fine version control.
- On the other hand, the java version control interface and its options constantly vary from one java release to the next.
- To access fine-grained version control for Java 4 (if you also have Java 5 and/or 6 installed), you must go to the directory c:\program files\java\j2re1.4.x_xx\bin (or the equivalent directory if you installed it somewhere else) and launch the file jpicpl32.exe, which is the Java 4 control panel.
- The equivalent for Java 5 is the file javacpl.exe, but this is the same as Java 6 (at the moment), so you don't really need to access it manually.
- "Does the JRE installation have a negative effect on portability?"
- In future, the best portability will probably be offered by a JNLP/Web Start variant of the Qedoc Quiz Player. See JNLP deployment. In short: go to a web page, click a link, and the Qedoc Quiz Player will immediately launch from the page.
