Setting the target version of Java in ant javac

Question

I need to compile a jar file using ant (1.7.0) to run under a specific version of Java (1.5). I currently have Java 1.6 on my machine. I have tried setting:

<target name="compile">
  <javac compiler="javac1.5" target="1.5" srcdir=.../>
</target>

I have also removed

<property name="build.compiler" value="modern"/>

and there is no properties file. I am running Java 1.6 on Linux/SUSE

Also is there a simple way of determining which version of Java is expected in the jar file.

score 92 · Accepted Answer · edited Dec 24 '22 at 06:26

92

Use "target" attribute and remove the 'compiler' attribute. See here. So it should go something like this:

<target name="compile">
  <javac target="1.5" srcdir=.../>
</target>

edited Dec 24 '22 at 06:26

starball

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answered Sep 28 '09 at 16:29

NawaMan

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8

I had to use source and bootclasspath attributes as well. See [here](http://docs.oracle.com/javase/7/docs/technotes/tools/solaris/javac.html#examples) for a cross compilation example. (there is direct correspondence with the ant attributes) – kon psych Jan 21 '13 at 13:22
6

It would be really nice if the answer could be modified to add `source` and `bootclasspath` – Jason S Jul 21 '14 at 15:13
it helps with a legacy app. – Breton F. Oct 05 '18 at 18:51
– Oleksii Kyslytsyn Apr 09 '20 at 11:14

score 50 · Answer 2 · answered May 24 '13 at 19:28

50

Both source and target should be specified. I recommend providing ant defaults, that way you do not need to specify source/target attribute for every javac task:

<property name="ant.build.javac.source" value="1.5"/>
<property name="ant.build.javac.target" value="1.5"/>

See Java cross-compiling notes for more information.

answered May 24 '13 at 19:28

user1338062

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– Oleksii Kyslytsyn Apr 09 '20 at 11:14

score 15 · Answer 3 · answered Sep 28 '09 at 16:38

15

To find the version of the java in the classfiles I used:

javap -verbose <classname>

which announces the version at the start as

minor version: 0
major version: 49

which corresponds to Java 1.5

answered Sep 28 '09 at 16:38

peter.murray.rust

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score 5 · Answer 4 · edited Dec 12 '12 at 02:12

5

You may also set {{ant.build.javac.target=1.5}} ant property to update default target version of task. See http://ant.apache.org/manual/javacprops.html#target

edited Dec 12 '12 at 02:12

peter.murray.rust

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answered Oct 09 '12 at 11:24

Eugene Petrenko

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{{ant.build.javac.target=15}} – Oleksii Kyslytsyn Apr 09 '20 at 11:14

Setting the target version of Java in ant javac

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