Im trying to create a layout that will show the received location updates in the text view, but i keep getting this error, what am i doing wrong?   Help would be appreciated, thanks in advance!  Here is the error:      E/AndroidRuntime: FATAL EXCEPTION: main                    Process: com.example.defro.app, PID: 7731                    java.lang.NullPointerException: Attempt to invoke virtual >method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null >object reference                         at com.example.defro.app.MainActivity$1.onLocationChanged(MainActivity.java:29)`   Row 29 is:   txtLoc.setText(String.valueOf(iaLocation.getLongitude() + ", " + iaLocation.getLatitude()));  Main_Activity:  public class MainActivity extends AppCompatActivity {  IALocationManager mLocationManager; IALocationListener mLocationListener = new IALocationListener() {     @Override     public void onLocationChanged(IALocation iaLocation) {         TextView txtLoc = (TextView) findViewById(R.id.textView);         txtLoc.setText(String.valueOf(iaLocation.getLongitude() + ", " + iaLocation.getLatitude()));      }      @Override     public void onStatusChanged(String s, int i, Bundle bundle) {      }  }; private final int CODE_PERMISSIONS = 1;  @Override protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);      mLocationManager = IALocationManager.create(this);       String[] neededPermissions = {             Manifest.permission.CHANGE_WIFI_STATE,             Manifest.permission.ACCESS_WIFI_STATE,             Manifest.permission.ACCESS_COARSE_LOCATION,             Manifest.permission.BLUETOOTH,             Manifest.permission.BLUETOOTH_ADMIN        };     ActivityCompat.requestPermissions(this, neededPermissions, CODE_PERMISSIONS);   } public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {     super.onRequestPermissionsResult(requestCode, permissions, grantResults);      //Handle if any of the permissions are denied, in grantResults }   protected void onResume() {     super.onResume();     mLocationManager.requestLocationUpdates(IALocationRequest.create(), mLocationListener);  }  protected void onPause() {     mLocationManager.removeLocationUpdates(mLocationListener);     super.onPause(); }  protected void onDestroy() {     mLocationManager.destroy();    super.onDestroy(); }   }  content_main.xml:  &lt;TextView     android:layout_width="wrap_content"     android:layout_height="23dp"     android:text="Lat, Long"     app:layout_constraintBottom_toBottomOf="parent"     app:layout_constraintHorizontal_bias="0.051"     app:layout_constraintLeft_toLeftOf="parent"     app:layout_constraintRight_toRightOf="parent"     app:layout_constraintTop_toTopOf="parent"     app:layout_constraintVertical_bias="0.032" /&gt;
What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?
Yesterday I was copying a single, 8 GB file to a USB with a slow, 7 MB/s write speed, while my RAM is 3 GB. While copying the system froze, to the point where I couldn't even move the cursor.  I managed to log into the text console, and ran iotop, it showed that a process named kswapd0 was taking 99.99% of IO.  Are there workarounds so copying a large file doesn't make my system unusable? Margin on child element moves parent element What can I do if I forgot my Windows password? I got a brand new Windows 7 machine, installed the operating system, created one account and forgot its password. What can I do?  There is no external CD, the operating system is loaded from somewhere inside the machine.  I already tried to remember passwords and tried all candidates with all possible combinations of caps lock, num lock etc. I'm looking for a phrase that describes trying to fix problems caused by underlying issues, with the result of compounding the issue. I usually call this "targeting surface problems rather than root problems", but my terminology is verbose.  Example 1: A government bans buying and selling bananas in the state. Later, it passes a clause allowing citizens to purchase imported bananas.  Example 2: A divided highway is erected with two lanes going in each direction but, since it gets lots of traffic, the shoulders are widened into new lanes. This leaves no shoulder room.  What would be a more concise phrase? I wish to remove Ubuntu and I'm not quite sure how. I know it has something to do with partitions. I have 3 partitions. 1. OS [683 GB]  2. Recovery [14 GB] 3. Ubuntu 12.04 LTS (E:)  I know it says Ubuntu but when I installed Ubuntu I think I put 14 gigabytes for it so I think its the recovery one but I'm not sure. I could have sworn I put more than 700 megabytes for it.  I have googled this and I can't seem to find an answer. Any help would be nice. How to make a blank page in Google Chrome at start-up? I want to argue that argue that $\pi(\alpha)=\alpha^3+3\alpha+3$ is an irreducible polynomial over the finite field with 5 elements $\mathbb{F}_5$. My approach was just to check that $\pi$ has no roots in $\mathbb{F}_5$. Is this right? Intro  I'm working on a lightweight package that allows you to put any content (typically LaTeX code) in an environment, then use that content multiple times, each time scanned separately, so you can use it both as verbatim output and interpreted as LaTeX.  Its main purpose is to typeset LaTeX code and its 'result' side-by-side; useful for documenting TeX packages without having to copy/paste code. But it has other purposes as well.  After experimenting with \scantokens until I gave up in tears, I arrived at the filecontents environment, which almost solved my problem singlehandedly!  The Problem  The problem is, when reintroducing filecontented code through \input, LaTeX adds an implicit newline at the end, which translates to whitespace that I can't seem to get rid of.  I've seen many semi-related questions floating around, with answers employing techniques like:   reading a file line-by-line, using \everyeof in some clever way, playing with \endlinechar or using packages such as catchfile   but none of them provides a clear answer to the following question:  The Question  How can I \input a file without getting the implicit newline?  Minimal Working Example  \documentclass[margin=1mm]{standalone}  \usepackage{filecontents}  \begin{filecontents*}{tmp.tex}     \LaTeX{}\end{filecontents*}  \begin{document}     \fbox{\input{tmp.tex}} \end{document}     Note the extra whitespace to the right of the box.  Note also that I'm definitely not adding any explicit whitespace. Even a manually produced file (so, not using filecontents) with no newlines at all exhibits the same problem. I'm attempting to get a better understanding of cryptography and have run into some questions about bcrypt.   Bcrypt relies on the blowfish cipher, which is a reversible method of encryption. But bcrypt is not reversible. How is that possible? Or am I mistaken? What does bcrypt do on top of blowfish to make it irreversible? Why does bcrypt use blowfish instead of twofish or threefish? Website home page design when there are multiple audiences I am in the process of creating a website which has two distinct audiences - in my case consumers and retailers.  When I first started the process just a few weeks ago I had followed the then model used by PayPal who too have to deal with distinct audiences.    However, having Googled around a bit for what the accepted wisdom is when dealing with website landing pages for segmented markets it appears to me that the current belief is that one just directs the visitor away from the landing page to other, segment focused, pages ASAP.  I have to admit that I am having trouble buying that philosophy.  To my mind it makes sense to provide at least some basic information - key benefits - for each segment on the landing page and then let viewers who linger long enough the opportunity to easily drill down to their own segment-focused page.  My own reasoning is that most first time visitors are liable to want to bounce away quickly and making them find and click on the segment page link is more likely to make them bounce than if they find enough to hold them on the landing page for a bit longer.  I'd like to have other views on this.  What are the pros and cons of the    Drive traffic to segment-focused page ASAP vs Provide some basic information - at least key benefits - for each segment on the landing page itself When installing software in debian systems we can put something like this:   sudo apt-get install -y chromium-browser  that way the installation occurs automatically, whitout asking to confirm installation [Y/n]. Can i do the same with pacman? $|A \cup B| = \mathfrak{c}$, then $A$ or $B$ has cardinality $\mathfrak{c}$. Determining the name of the VMware host of a VM guest - from the guest I feel stupid asking, but I can't seem to find the answer to this anywhere. I'm trying to follow  to edit my bash prompt, but there is no .bashrc in either my user directory (~/.bashrc), or in my home directory, or in the main file system directory.   There is no .bashrc in /etc/ (there is a bash.bashrc, however).   Do I create a .bashrc file in my user or home directory? Is there a better, more recent set of instructions for modifying the bash prompt? Is it feasible to build a stream cipher from a cryptographic hash function? A few years ago I devised a symmetric-key system that worked like so:  H()   = some hashing function h     = the number of bits in the result of H() key   = bits to be used as a key ^     = the XOR operation +     = concatenation len() = the length function (in bits)  max = ceiling(len(cipertext) / h) pad = pad_0 + ... + pad_max pad_0 = H(key) ^ H(plaintext) pad_n = H(pad_(n-1)) cipherpart_n = plaintext_n ^ pad_n ciphertext = H(plaintext) + cipherpart_0  + ... cipherpart_max   Basically, it builds up a "pad" based on the hash of the message and hash of the key and XORs the message against it.  I am not actually an expert, so I was wondering why an approach like this isn't very common. Suppose that a box contains 10 red balls, 20 green balls, and 30 blue balls.   Suppose also that balls are drawn from the box one at a time at random.  What is the probability that all the red balls are drawn before the blue or green balls are themselves exhausted. What is the probability that as the last red ball is drawn, there remains at least one blue and one green left in the box.  The answer I was given is $\dfrac{7}{12}$ and a general equation is: $$ \dfrac{b g}{1-b}+\dfrac{b g}{1-g} $$ where $$ g=\dfrac{20}{60},b=\dfrac{30}{60} $$ but why? I want to install Windows XP on my desktop computer (only XP), but my CD drive is not working.  I've only found installation tutorials on how to install it on the pen drive rather than from the pen drive.  How can I install Windows XP from a USB flash drive? Getting text from the Resource file in asp.net 4 Is there a term for grammatical mistakes as a result of trying too hard? Do separate autofocus motors exist for entry level Nikon DSLRs?