Does Eclipse 4.4 (Luna) Require Java 1.7

Question

I decided to update my eclipse to 4.4 (luna release). When I try to launch it however, I get an error stating that eclipse requires 1.7 or later of java jvm.

Just wanted to see if this is true and if it is possible to get it running with 1.6 (specifically 1.6.0_65)

Solution 1

If there is an explicit message stating that 1.7 or later is required when you run it with 1.6, I expect this to be a strong (ie blocking) minimum requirement. Eclipse Luna (4.4) is the first release requiring 1.7:

http://wiki.eclipse.org/Eclipse/Installation

And still, if you still doubt it you can verify for which version it was compiled. For every Eclipse classes run the following command:

javap -verbose EclipseClass.class

Look for Major Version. If value is 51 this means it was compiled for java 1.7, so you are out of luck for 1.6. The magic numbers for major versions are :

J2SE 8 = 52 (0x34 hex),
J2SE 7 = 51 (0x33 hex),
J2SE 6.0 = 50 (0x32 hex),
J2SE 5.0 = 49 (0x31 hex),
JDK 1.4 = 48 (0x30 hex),
JDK 1.3 = 47 (0x2F hex),
JDK 1.2 = 46 (0x2E hex),
JDK 1.1 = 45 (0x2D hex).

and are described here:

http://en.wikipedia.org/wiki/Java_class_file#Magic_Number

Thing is, each eclipse bundle have different minimum requirements, so this may not be a good option for a platform as big as Eclipse. Anyway, I mention it because its good to know.

Solution 2

I also had this problem during the IDE Luna installation. In my case, to solve this problem, I had that change the system variables in win 7. In my computer was the variable that was did referenced the jdk 6... after that I changed it, I could open it again.

This link helped me:

Comments

[Peter Becker]

Shouldn't that be: "check all Eclipse class files" instead of "choose one"? As long as only one is compiled with target 1.7 it won't work on any JRE older than that.

[Mathieu Fortin]

Right. I thought at first that all bundles were compiled for the same target. But I verified and each bundle has its own.

[Neon]

Yup, see Eclipse BUG Bug 423734 - Require Java Version 1.7 or higher in all EPP packages bugs.eclipse.org/bugs/show_bug.cgi?id=423734 -or- Eclipse Planning Council notes for Luna (4.4) Planning at wiki.eclipse.org/Planning_Council/December_11_2013