Button onClick doesn't work in Fragment, throws "null object reference" error even after declaring it
What is a NullPointerException, and how do I fix it?
Reputation graph not interactable with a touch screen How to disable GNOME keyring? I want to disable GNOME keyring globally on my machine. So I deleted the lines  auth    optional        pam_gnome_keyring.so session optional        pam_gnome_keyring.so auto_start   in /etc/pam.d/gdm. It seems to me that this has no effect. When I lock in the syslog writes  Aug 24 18:37:03 foobar gnome-screensaver-dialog: gkr-pam: unlocked login keyring   and another user sees a menu window where he hs to enter his credentials. So what is the correct way to disable keyring for every user on that machine? Combining several static libraries into one using CMake Turning a cipher into a hashing function Is the universe fundamentally deterministic? I'm not sure if this is the right place to ask this question. I realise that this maybe a borderline philosophical question at this point in time, therefore feel free to close this question if you think that this is a duplicate or inappropriate for this forum. Anyway, I'm an electrical engineer and I have some basic knowledge of quantum mechanics. I know that Schrödinger's equation is deterministic. However, quantum mechanics is much deeper than that and I would like to learn more. If this question is not clearly answerable at this point than can anyone point out some recognized sources that try to answer this question. I would appreciate it if the source is scientific and more specifically, is related to quantum theory. Change web folders names with uppercase to lowercase or not? I'm quite new to neural networks and currently I'm trying to train a non convolutional neural network on the MNIST data set. I'm observing some behaviour I don't quite understand.   This is the code written with keras as the library:  # the data, split between train and test sets (x_train, y_train), (x_test, y_test) = fashion_mnist.load_data()  y_train = keras.utils.to_categorical(y_train, 10) y_test = keras.utils.to_categorical(y_test, 10) model = Sequential()  early_stopper = EarlyStopping(patience=3)  model.add(Flatten(input_shape=(28,28))) model.add(Dense(128, activation="relu")) model.add(Dense(128, activation="relu")) model.add(Dense(10, activation="softmax")) model.compile(loss="categorical_crossentropy", optimizer="adam", metrics=["accuracy"])  model.fit(x_train, y_train, epochs=20, validation_data=(x_test, y_test), callbacks=[early_stopper])   This gives me a validation_acc of around 20%. The funny thing is, when I change the activation functions to "sigmoid", the loss function to "mean_squared_error" and the optimizer to "sgd" my performance improves to around 85% after 50 epochs.   Having read  I wonder what's the reason for the bad performance of the network I presented in the code. ReLU, cross-entropy and a dynamic optimizer like Adam all seem to improve on the idea of a very vanilla neural network with stochastic gradient optimization, mean squared error as loss and sigmoid activation functions. Yet I get a really bad performance and if I increase the number of nodes in the hidden layers I often get a network that doesn't learn at all.   EDIT: I figured out it has something to do with me not normalizing the input to values between 0 and 1 ... but why is this the problem? How to make Portable QGIS 3 It has been suggested by my employer that i should get the Hepatitis B vaccine to protect myself.  I have had two of the three parts, but this is the first time i have had a vaccine in more than one session.  The vaccine is in 3 doses, each around a month apart, followed up by a blood test.  Why is the Hepatitis B vaccine split into 3, any what is the blood test for at the end? Magic quotes in PHP According to the , in order to make code more portable, they recommend using something like the following for escaping data:  if (!get_magic_quotes_gpc()) {     $lastname = addslashes($_POST['lastname']); } else {     $lastname = $_POST['lastname']; }   I have other validation checks that I will be performing, but how secure is the above strictly in terms of escaping data? I also saw that magic quotes will be deprecated in PHP 6. How will that affect the above code? I would prefer not to have to rely on a database-specific escaping function like mysql_real_escape_string(). Gandalf (as with all the Istari) did not have a corporeal form before coming to Middle-earth and was essentially ageless. We also know that Gandalf did age, albeit very slowly, while on Middle Earth. By the end of the Third Age (before battling Durin's Bane), he had the appearance of an old human male (non-Númenórean, etc) in his 70's or 80's. This leads me to wonder:  Is there any indication in Tolkien's writings that describes Gandalf's appearance (in human-looking years) when he arrived in Middle Earth? In other words, was Gandalf the Grey originally "Gandalf the Tall Dark &amp; Handsome in his 20's"?  I'm not talking about his actual age, but rather his appearance in human years. Can I color text by using an image, so that the color isn't flat? I'm using tikz to attempt to make a book cover, and I have a "wallpaper" image that looks like leather (not that I've handled that many leather-bound books). I'm using the node command to place text over the top of it, but none of the colors I've experimented with look decent.  Can I use an image of gold-leaf as the fill/stroke for the text? Or for that matter, for the path lines as well?  I've tried googling for this, but I can't figure out a set of keywords non-generic enough to pull back useful results. When disconnecting from WebSphere MQ with C# client TCP connections are still in CLOSE_WAIT status Number theory in Physics As a Graduate Mathematics student, my interest lies in Number theory. I am curious to know if Number theory has any connections or applications to physics. I have never even heard of any applications of Number theory to physics. I have heard Applications of linear algebra and analysis to many branches of physics, but not number theory.  Waiting forward in receiving interesting answers! Is it possible to import comments into a chat room without the link appearing? Question: For an answer on a stack exchange site with say 8 comments, how can I / is it possible to import the comments into a chat room? Background: I was helping with a  and made several comments before I saw the link to auto-import comments into a chat room.  This was awesome by the way!! Note that the person who asked the question left a link to the chat room in a comment. I wanted to make a similar chat room  because I edited an answer which wasn't mine and added a paragraph.  I wanted to chat with the answer's author @JonHopkins to say, 'hey feel free to remove my edit -- just wanted to add my $0.02' -- especially as the stack exchange engines said not to add an additional answer.  HOWEVER, there was no link to auto-import the comments -- probably because I hadn't previously left one, but I'm not sure. So I ask here, Stack Exchange Gurus, could a static link be added to auto-import a series of comments into a chat session? I get the curvature tensor in General Relativity, it is “just” math. Does space-time REALLY curves as a tangible thing, or is Einstein proposing a mathematical abstraction?  More naively, please allow, is space-time a real physical “something” like a “new ether”? If yes, does anyone have any idea what is it made off? Example 1) Let's say I have some random creature with protection from white, and my opponent plays , a white card with the effect "Destroy all creatures." Can my creature with protection from white be destroyed by a white card that isn't actually targeting it specifically?  Example 2) I was playing a match with a friend where I had  on the field against his 3 zombies. Is he able to declare his zombies as blockers even though Elite Inquisitor has "protection" from zombies?  If he can declare them as blockers, does protection mean that no damage is dealt by the zombies to  Elite Inquisitor? Replace background while using HDRI for lighting? How can I replace the background of my scene, but keep the reflections and lighting generated from my HDRI? If $X$ and $Y$ are sets, their cartesian product $X\times Y$ is a set. In ZFC set theory, every element object is a set. We know or feel that if $X$ and $Y$ are sets, their cartesian product $X\times Y$ is a set.  My question is: Why if $X$ and $Y$ are sets, their cartesian product $X\times Y$ is a set? Apollonius circle, its radius and center