(I can understand most of your French posts, but unfortunately can't write French good enough, so let me use English please: )
Do you use Oracle's Java 7 on the Raspberry Pi, which is part of Raspbian since autumn 2013, or do you the Java version which has been part of Raspbian before? Because Oracle's Java version is optimized for the ARM and hence faster.
should result in:
Code: Select all
me@Pi ~ $ java -version
java version "1.7.0_40"
Java(TM) SE Runtime Environment (build 1.7.0_40-b43)
Java HotSpot(TM) Client VM (build 24.0-b56, mixed mode)
The Jazelle part of the Pi's ARM CPU does a god job in running JVM byte-code, I think (keeping in mind it's a 700 MHz RISC CPU). Of course it's slower than on a 3 GHz 80 Watt Intel/AMD power-hog.
It also depends on the Java application you want to run on the Pi. Normal non-visual Java programs or programs with a light usage of a GUI (graphical user interface) run fine in my experience. Programs with heavy GUI or visuals (like a ton of Swing or Java2D components) are usually too slow however, for example Netbeans: it runs, but it's too slow.
So, for such heavy visual programs it would be very necessary to use hardware acclerated Java2D/Swing on the Pi which however isn't there (on your Linux or Windos PC, Java2D and partly Swing uses the graphics card).
In case you want to make own Java programs doing visual thing on the Pi, you should try out the new Java 8 beta and its built-in JavaFX library, which does use the graphics card to render 2D and 3D components, i.e. DirectX on Windos, OpenGL on Linux or OpenGL-ES on smaller Linux devices like our Pi. On the latter JavaFX uses a non-X11 fullscreen always.
If interested, please have a look at this thread of mine: Accelerated 2D & 3D with JavaFX8 or ...?