Everything worked fine and I never had any problems with this code. But somehow I now get a null object when I try to receive a Tab that is not in the first position:     java.lang.NullPointerException: Attempt to invoke virtual method 'android.support.design.widget.TabLayout$Tab android.support.design.widget.TabLayout$Tab.setCustomView(android.view.View)' on a null object reference   tabLayoutSetup is called in onCreateView.   private void tabLayoutSetup(){     // Get the ViewPager and set it's PagerAdapter so that it can display items     Bugger.t(context,"tablayout");     viewPager.setAdapter(pagerAdapter);     // Give the TabLayout the ViewPager     tabLayout.setupWithViewPager(viewPager);      createTabs();  }  //this method is creating all tabs for account's tablayout private void createTabs(){     TabLayout.Tab ShareTab = tabLayout.getTabAt(0);     TabLayout.Tab MarkTab = tabLayout.getTabAt(1);      //***********************************************************************************************************     //inflating template for first tab, Activities.     View TabView = LayoutInflater.from(context).inflate(R.layout.account_tablayout_customtab, null); //template     TextView titel = (TextView) TabView.findViewById(R.id.tab_titel);     //populating first template for 'Activities'     titel.setText(getResources().getString(R.string.SharesTab));     titel.setTextColor(ContextCompat.getColor(context,R.color.tabLayout_active));     ShareTab.setCustomView(TabView);      //**********************************************************************************************************     //inflating template for second tab, Messages.     TabView = LayoutInflater.from(context).inflate(R.layout.account_tablayout_customtab, null); //template     titel = (TextView) TabView.findViewById(R.id.tab_titel);     //populating second template for 'Messages'     titel.setText(getResources().getString(R.string.MarkTab));     MarkTab.setCustomView(TabView);   It's really strange because it worked smoothly before. Receiving the Tab at the position 0 (.getTabAt(0)) is not a problem at all. However, I cannot receive the Tab at the position one.  XML:  &lt;android.support.design.widget.TabLayout             android:id="@+id/account_tabLayout"             android:layout_width="match_parent"             android:layout_height="52dp"             android:layout_marginTop="12dp"             android:visibility="visible"             app:layout_constraintEnd_toEndOf="parent"             app:layout_constraintStart_toStartOf="parent"             app:layout_constraintTop_toBottomOf="@+id/account_bio"&gt;           &lt;/android.support.design.widget.TabLayout&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?
Remove element of a regular array I have an array of Foo objects. How do I remove the second element of the array?  I need something similar to RemoveAt() but for a regular array. If $f$ is a continuous function with $\displaystyle \int_{0}^{x}f(t)dt\rightarrow \infty$ as $|x|\rightarrow \infty\;,$ Then show that every line $y=mx$ Intersect the curve $\displaystyle y^2+\int_{0}^{x}f(t)dt=2$  $\bf{My\; Try::}$ Put $y=mx$ in $$\displaystyle y^2+\int_{0}^{x}f(t)dt=2\;,$$ We get $$\displaystyle m^2x^2+y^2+\int_{0}^{x}f(t)dt=2.$$ We can write it as $$\displaystyle 2\int_{0}^{x}2m^2tdt+\int_{0}^{x}f(t)dt=2$$ So $$\displaystyle \int_{0}^{x}\left[2m^2t+f(t)\right]dt-2 =0$$ Now Let $$g(x) = \displaystyle \int_{0}^{x}\left[2m^2t+f(t)\right]dt-2.\;,$$ When $x\rightarrow \infty\;,$ Then $g(x)\rightarrow \infty.$ (Where $g(x)$ is an Continuous function.) Now I did not Understand How can i solve that, Help me Thanks Lightning Community Does Not Support pubsub for Lightning Web Components? Has anyone successfully used the pubsub module from lwc-recipes to enable inter-component communication in a Lightning Community?  The registerListener function in the pubsub module throws an error because the pageRef property is undefined.  Or is pubsub designed for Lightning Experience only? What the #$@&%*! is that called? Is there a name for the use of symbols in place of curse words, for example #$@&amp;%*!? I have a Python script which I would like to execute at every startup. I can run it by adding this to the startup applications:  python3 /path/to/script.py   That works, but it doesn't open a terminal window, so I can't see the program's output. How could I make it open a terminal window and execute the script in there?  Note: I get the window to stay open with input(' ') at the end of the Python script. Thanks! In my .bib file, I have two entries with exactly the same author names:  @article{Seshadrinathan2010A-Subjective-St,     Author = {K. Seshadrinathan and R. Soundararajan and A. C. Bovik and L. K. Cormack}, ....  @article{Seshadrinathan2009Study-of-Subjec,     Author = {K. Seshadrinathan and R. Soundararajan and A. C. Bovik and L. K. Cormack}, ....   When cited after each other, and typeset with the IEEEtran bibliography style, the .bbl file reads:  \bibitem{Seshadrinathan2010A-Subjective-St} K.~Seshadrinathan, R.~Soundararajan, A.~C. Bovik, and L.~K. Cormack, ``A   subjective study to evaluate video quality assessment algorithms,''   \emph{SPIE Proceedings Human Vision and Electronic Imaging}, 2010.  \bibitem{Seshadrinathan2009Study-of-Subjec} ------, ``Study of subjective and objective quality assessment of video,''   \emph{IEEE Transactions on Image Processing}, 2009.   As you can see, the author names have been replaced with ------. It looks like this in the final PDF:    Is this normal behavior? Can someone identify this book, where children are bred for specific jobs? Things I remember about this book:   Every child was selected for a certain job/career; If twins were born, one was always killed; Seeing colors for the first time (describing the color of an apple); Seeing war and death and poverty.   Does anyone have any idea what this book might be? How many Shutter Clicks on a New Camera considered normal? How many Shutter Clicks on a New Camera considered normal?    I purchased a quotes new Nikon D750 and checked the shutter count and it has 264 Shutter Clik count on it.    Is that suspect of a returned purchase or used camera? Combinations of sets raised to the power of a prime modulus: $\binom{p^{\alpha}-1}k \equiv (-1)^k \pmod p$ How to remove symbolic link I was trying to create this symbolic link:  sudo ln -s /usr/share/phpmyadmin /var/www/phpmyadmin   but I accidentally typed:  sudo ln -s /usr/share/php,yad,in /var/www/phpmyadmin   So now I want to correct it but it says symbolic link already exist. SimpleXML: Selecting Elements Which Have A Certain Attribute Value How to plot periodic function's graphic? How can you profile a Python script? and other coding contests often have a maximum time to run or people boast of how fast their particular solution runs. With Python, sometimes the approaches are somewhat kludgey - i.e., adding timing code to __main__.  What is a good way to profile how long a Python program takes to run? Don't show pending suggested edits to me after I run out of votes What exactly makes quantum computers faster than classical computers? Make an Ubuntu bootable USB drive for a PC using Mac? "Think of" versus "think about" Could someone help me to understand when I should use think of and when think about in sentences?  What is the difference between using one or the other? I am trying to solve a variation on the .  In this scenario, someone is selecting coupons at random with replacement from n different possible coupons. However, the person is not selecting coupons one at a time, but instead, in batches.  Here's an example problem formulation: There are 100 distinct coupons. A person makes selections in 10-coupon batches at random (each coupon with replacement). What is the expected number of batches necessary to have selected 80 unique coupons?  I have been able to determine the expected number of selections necessary to have selected k unique coupons when selecting one at a time (much like Henry's ), but I'm a bit stumped as to how to go about solving it with this particular wrinkle.  Any tips/guidance would be greatly appreciated. How to use GROUP BY to concatenate strings in MySQL? Basically the question is how to get from this:   foo_id   foo_name 1        A 1        B 2        C   to this:   foo_id   foo_name 1        A B 2        C Showing that $f$ is linear function if $\forall z \in \mathbb{C}$, $|f(z)| \leq 1 + |z|$. Let $f$ be an entire function that satisfies $|f(z)| \leq 1 + |z|$ for all $z\in \mathbb{C}$. Show that $f(z) = az +b$ for fixed complex numbers $a,b$.    The hint tells us to try and use Cauchy's Integral Formula on an arbitrary circle.    This is my attempt: Consider an arbitrary large circle with centre $0$ and let $\Upsilon$ be the contour around this circle.    Then $$\int_{\Upsilon} \frac{f(z)}{z^{n+1}} \mathrm{d}z = \frac{2\pi i}{n!}f^{(n)}(0).$$    Note that $$\int_{\Upsilon}\frac{f(z)}{z^{n+1}} \leq \int_{\Upsilon}\left|\frac{f(z)}{z^{n+1}} \right|\leq \int_{\Upsilon} \frac{1}{|z^{n+1}|} + \frac{1}{|z|^n}$$ and the right hand side is $0$ by Cauchy's Integral Formula. I'm not sure if the first equality is valid, and not sure where to go from here.