I have downloaded a portable version of the Java 8 Runtime Environment, and I intend to ship it with my Java app.
However, the full JRE is 179 MB, and I want to shrink it down a bit.
Can I exclude some files from my distribution of the JRE, and still have it remain functional?
Note: I am asking for a technical answer, not legal advice. Also, this is a self-answer.
Yes. According to the Java 8 README, certain folders and files can be removed.
For starters, everything outside of bin/ and lib/ can be removed.
After that, the following folders can removed wholesale:
bin/dtplugin/
bin/plugin2/
lib/deploy/
lib/desktop/
lib/ext/
lib/jfr/
lib/oblique-fonts/
On Windows, the following files can be cut:
bin/deploy.dll
bin/jabswitch.exe
bin/java_crw_demo.dll
bin/JavaAccessBridge-32.dll
bin/JavaAccessBridge-64.dll
bin/javacpl.cpl
bin/javacpl.exe
bin/javaws.exe
bin/JAWTAccessBridge-32.dll
bin/JAWTAccessBridge-64.dll
bin/jfr.dll
bin/jucheck.exe
bin/keytool.exe
bin/kinit.exe
bin/klist.exe
bin/ktab.exe
bin/orbd.exe
bin/policytool.exe
bin/rmid.dll
bin/rmid.exe
bin/rmiregistry.exe
bin/servertool.exe
bin/tnameserv.exe
bin/WindowsAccessBridge-32.dll
bin/WindowsAccessBridge.dll
bin/wsdetect.dll
and if you are directly linking against the JVM or using a custom launcher, you can cut these files:
bin/java.exe
bin/javaw.exe
On Linux:
bin/javaws
bin/keytool
bin/orbd
bin/policytool
bin/rmid
bin/rmiregistry
bin/servertool
bin/tnameserv
On all platforms:
lib/deploy.jar
lib/jfr.jar
lib/plugin.jar
lib/security/cacerts
On Windows:
bin/decora-sse.dll
bin/fxplugins.dll
bin/glass.dll
bin/glib-lite.dll
bin/gstreamer-lite.dll
bin/javafx_font_t2k.dll
bin/javafx-font.dll
bin/javafx-iio.dll
bin/jfxmedia.dll
bin/jfxwebkit.dll
bin/prism_common.dll
bin/prism_es2.dll
bin/prism_sw.dll
bin/prism-d3d.dll
On macOS:
lib/fxplugins.dylib
lib/libdecora_sse.so
lib/libdecora-sse.dylib
lib/libfxplugins.so
lib/libglass.dylib
lib/libglib-lite.dylib
lib/libgstreamer-lite.dylib
lib/libjavafx_font_t2k.dylib
lib/libjavafx-font.dylib
lib/libjavafx-iio.dylib
lib/libjfxmedia.dylib
lib/libjfxwebkit.dylib
lib/libprism_common.dylib
lib/libprism_sw.dylib
lib/libprism-es2.dylib
On Linux:
lib/amd64/libdecora_sse.so
lib/amd64/libfxplugins.so
lib/amd64/libglass.so
lib/amd64/libgstreamer-lite.so
lib/amd64/libjavafx_font_freetype.so
lib/amd64/libjavafx_font_pango.so
lib/amd64/libjavafx_font_t2k.so
lib/amd64/libjavafx-font.so
lib/amd64/libjavafx-iio.so
lib/amd64/libjfxmedia.so
lib/amd64/libjfxwebkit.so
lib/amd64/libprism_common.so
lib/amd64/libprism_es2.so
lib/amd64/libprism_sw.so
lib/amd64/libprism-es2.so
lib/i386/libdecora_sse.so
lib/i386/libfxplugins.so
lib/i386/libglass.so
lib/i386/libgstreamer-lite.so
lib/i386/libjavafx_font_freetype.so
lib/i386/libjavafx_font_pango.so
lib/i386/libjavafx_font_t2k.so
lib/i386/libjavafx-font.so
lib/i386/libjavafx-iio.so
lib/i386/libjfxmedia.so
lib/i386/libjfxwebkit.so
lib/i386/libprism_common.so
lib/i386/libprism_es2.so
lib/i386/libprism_sw.so
On all platforms:
lib/ant-javafx.jar
lib/javafx.properties
lib/jfxswt.jar
THIRDPARTYLICENSEREADME-JAVAFX.txt
On a copy of the 64-bit JRE 8u131 for Windows, removing these files reduces the JRE directory from 179 MB to 98 MB, a reduction of 45%. The result is still capable of loading Java applications, including all of the Swing Component demos.