You confuse me: I thought a and b are float vectors - that is, vectors containing actual numbers, not pointers (for example to a Float class). As such, you can not .clone() them.
Did you use Float (with capital "F") instead of float (with lower case "f")? Floats are classes surrounding float. If you want to work time-critical, you should use the simple float: float[] a = new float[3]; float[] b = new float[3]; a[0] = 1.2f; a[1] = 2.3f; ... and NOT Float[] a = new Float[3]; a[0] = new Float(1.2f); a[1] = new Float(2.3f); ... Peli On Aug 26, 2:28 am, Rud <[email protected]> wrote: > System.arraycopy does not do a deep copy. I just tried it. But it is > very fast. <grin> > > I setup the timing test. I did 5000 passes over the copy loops; > > 522 ms for (i=0; i<3; i++) a[i] = b[i].clone(); > 453 ms for(i=3; i-->0;) a[i] = b[i].clone(); > 447 ms int pos = 0; for(type x; b) a[pos++] = x.clone(); > > I had written a type.clone() to make the deep copy for each array > element. I was surprised that the for_each version did so well. I > won't put much faith in the timing differences between it and the > subtraction version. > > Rudhttp://mysticlakesoftware.blogspot.com/ > > On Aug 25, 8:00 am, Peli <[email protected]> wrote: > > > To deep copy an array, you can use > > System.arraycopy(..)http://developer.android.com/reference/java/lang/System.html#arraycop... > > > System.arraycopy(b, 0, a, 0, 3); > > > but for a float array of length 3, you can simply write > > a[0]=b[0]; > > a[1]=b[1]; > > a[2]=b[2]; > > > or > > for (i=0; i<3; i++) a[i] = b[i]; > > > I've never tried to profile which of the 3 ways is actually the > > fastest on a real Android device. If someone has the time, please try > > all 3 in a tight loop and report back :-) > > > (there is also > > for(i=3; i-->0;) a[i] = b[i]; > > which may be even faster?) > > > Note: all assume that you have initialized a already beforehand, > > a = new float[3]; > > > Peli > > > On Aug 25, 8:24 am, Rud <[email protected]> wrote: > > > > Hi, > > > > The code is originally from my Blog. The reason for the clone is > > > explained there. > > > > I admit to not having worked with Java enough to have the deep > > > understanding of how containers deal with objects. In my application I > > > ran into a problem trying to make a copy of an array and had to write > > > my own copy. > > > > I had a set of data that gets consumed while the app runs. I wanted to > > > reset that data at times. I put the data in an array and then cloned > > > it to the working array. I was surprised when the original data got > > > changed when the cloned data was changed. I also realized that the > > > sensor code wasn't doing what I thought it was but haven't taken the > > > time to adjust it. > > > > How in Java do you actually make a deep copy of an array? > > > > Rudhttp://mysticlakesoftware.blogspot.com/ > > > > On Aug 21, 7:07 am, Peli <[email protected]> wrote: > > > > > > .... = event.values.clone(); > > > > > Note that this creates new objects constantly that have to be garbage > > > > collected later. Depending on the kind of application, it may be > > > > better to just copy the values into a persisting array. > > > > > Peliwww.openintents.org > > > > > On Aug 21, 4:06 am, mscwd01 <[email protected]> wrote: > > > > > > Heres my code, which works: > > > > > > public void onSensorChanged(SensorEvent event) { > > > > > > Sensor sensor = event.sensor; > > > > > int type = sensor.getType(); > > > > > switch (type) { > > > > > case Sensor.TYPE_MAGNETIC_FIELD: > > > > > mags = event.values.clone(); > > > > > isReady = true; > > > > > break; > > > > > case Sensor.TYPE_ACCELEROMETER: > > > > > accels = event.values.clone(); > > > > > break; > > > > > case Sensor.TYPE_ORIENTATION: > > > > > orients = event.values.clone(); > > > > > break; > > > > > } > > > > > > if (mags != null && accels != null && isReady) { > > > > > isReady = false; > > > > > > SensorManager.getRotationMatrix(R, I, accels, > > > > > mags); > > > > > SensorManager.remapCoordinateSystem(R, > > > > > SensorManager.AXIS_Y, SensorManager.AXIS_MINUS_X, outR); > > > > > SensorManager.getOrientation(outR, values); > > > > > > azimuth = > > > > > getAzimuth(-convert.radToDeg(values[0])); > > > > > pitch= convert.radToDeg(values[1]); > > > > > roll = -convert.radToDeg(values[2]); > > > > > > } > > > > > > } > > > > > > On Aug 21, 2:39 am, Mike Collins <[email protected]> wrote: > > > > > > > I have a sensor event handler that gets fired and I have no problem > > > > > > getting and processing acceleration readings. However this code > > > > > > always fails. > > > > > > > if (event.sensor.getType() == > > > > > > Sensor.TYPE_ACCELEROMETER) > > > > > > { > > > > > > float[] geomagnetic = new float[3]; > > > > > > geomagnetic[0] = geomagnetic[1] = > > > > > > geomagnetic[2] = 0; > > > > > > > float[] r = new float[9]; > > > > > > float[] I = new float[9]; > > > > > > boolean b = > > > > > > SensorManager.getRotationMatrix(r, I, event.values.clone > > > > > > (), event.values.clone()); > > > > > > if ( ! b) > > > > > > { > > > > > > Log.e(LOG_TAG, "getRotationMatrix > > > > > > failed"); > > > > > > return; > > > > > > } > > > > > > ... > > > > > > > tia, > > > > > > mike- Hide quoted text - > > > > > - Show quoted text -- Hide quoted text - > > > - Show quoted text - --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Android Developers" group. 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