java.lang.NullPointException and POS system java console
What is a NullPointerException, and how do I fix it?
Does $k+\aleph_0=\mathfrak{c}$ imply $k=\mathfrak{c}$ without the Axiom of Choice? Why is $\mathbb{R}^2$ not a subspace of $\mathbb{R}^3$? I cannot understand why $\mathbb{R}^2$ is not a subspace of $\mathbb{R}^3$.   My reasoning is as follows: Choose any elements $v_1$ and $v_2$ from $\mathbb{R}^2$, add them together you get an element of $\mathbb{R}^2$ and same for scalar multiplication and $0$ vector is an element of $\mathbb{R}^2$. So where did I go wrong? I just found out about the Mesh Display : Length feature in the "N" panel (thanks to ) that allows one to measure the length of a face or vertice.  But my first encounter with this tool gives me complex feelings of love and hate, see how, as I was trying to measure the aspect ratio of this TV screen, I am getting WIDTH = 20.33 and HEIGHT = 37.57.  These values seem awfully wrong, since my betrusted eyes tell me the height should be shorter than the width.    I have tried measuring the single vertices as well, to identical results. I've tried latexdef which does not handle --- as the operand. And \texemdash is defined as a character. So that leaves me once again leaning on the collective wisdom of the group :) I am planning to travel to India (COK airport, Kerala) from United States. I want to take my laptop as well as my tablet (iPad). Am I allowed to take both in my backpack with my documents related my work. I think I am allowed to take only one computer as per the rule. Will the customs consider my iPad as a computer?  What all I can take?   One of my friends took 2 laptops (1 work and 1 personal) and had trouble at the airport.  Also I am planning to take some wristwatches (7 of them, each avg price is 45 $). I read in a website that I can take stuff up to max 35000 INR. Is that true? In that case, how will I manage my stuff? What happened to the Dursleys? As last seen, the Dursleys are forced to move by the ministry of magic, put into protective custody by the ministry. However, the ministry fell only a few weeks later, and there was evidence that it couldn't be trusted, even then. Are they still alive, and if so, how did they survive the purge from the ministry? Two players, $A$ and $B$, alternately and independently flip a coin and the first player to get a head wins. Assume player $A$ flips first.  If the coin is fair, what is the probability that $A$ wins?   So $A$ only flips on odd tosses. So the probability of winning would be $$ P =\frac{1}{2}+\left(\frac{1}{2} \right)^{2} \frac{1}{2} + \cdots+ \left(\frac{1}{2} \right)^{2n} \frac{1}{2}$$  Is that right? It seems that if $A$ only flips on odd tosses, this shouldn't matter. Either $A$ can win on his first toss, his second toss, ...., or his $n^{th}$ toss. So the third flip of the coin is actually $A$'s second toss. So shouldn't it be $$P = \frac{1}{2} + \left(\frac{1}{2} \right)^{2} + \left(\frac{1}{2} \right)^{3} + \cdots$$ Found the following in an Oracle-based application that we're migrating (generalized):  SELECT     Table1.Category1,     Table1.Category2,     count(*) as Total,     count(Tab2.Stat) AS Stat FROM Table1, Table2 WHERE (Table1.PrimaryKey = Table2.ForeignKey(+)) GROUP BY Table1.Category1, Table1.Category2   What does (+) do in a WHERE clause? I've never seen it used like that before. No, not like this:    Hear me out!  As Stack Overflow grows, it becomes increasingly ridden with extremely newbie and mediocre questions. It's just natural. The team are fighting hard to keep the crap out, but there are many very basic questions that are okay on their own. They don't deserve to be kicked out* - they are just very, very, very basic and/or localized.   Too much basicness tires users who are interested in discussing more advanced topics.  As has been discussed many times over, the voting system is not suited to identify advanced questions due to what is known as the . A group of people will vote on what they understand, which puts truly expert questions at a natural disadvantage that a democratic voting system can't overcome.  Now, there is a small number of users on Stack Overflow who I, as a user, know share my basic values (like, teaching a man to fish rather than fishing for them); I also know they are experts in their fields. It is safe to assume that what these users regard an interesting question worthy of attention, is likely to be interesting to me as well.      The idea is to introduce an opt-in "follow" mechanism that allows followed users to share what they find interesting, with very little fuss and on a purely opt-in basis.   Allow every SO user to follow any other SO user with a certain minimum rep, say 3000.   To every user who is being followed (or every user), display a new link underneath every question, "Recommend".    Introduce a new filtered view somewhere, named "Recommended". The view will show me all questions that my followed users are recommending.   Whenever I browse a list of questions, highlight those questions that have been recommended by my followed users. (I haven't put much thought into how to implement this graphically - you get the drift.)      I'm not especially fond of social networking, and I think most of it doesn't have a place on SO. But I'm starting to think this specific thing could be the right way to go in order to tell apart expert content from the 10000th dreary "how do I upload a file" question.  This is an entirely opt-in feature - unless I actively follow some users, I will never notice this.   Maybe for a bit of ego-stroking, the profile page can show how many users follow you. Or even who. Everything else would simply be kept under wraps - no publication of follower data in the data dump, no follower leagues or anything like that.      * At least not under current SO rules. Maybe those rules need to be changed - but that is a different discussion. In my game, XP needed to reach the next level is Current Level × Level Threshold.  Given that, how can I get my current level from the total XP ever earned?    For example:  Level Threshold = 50 Current Level = 1   Starting at level 1, I would need (1 × 50) = 50 XP to get to level 2, and so on.  Level 1: 50 XP needed to reach level 2 Level 2: 100 more XP needed to reach level 3 Level 3: 150 more XP needed to reach level 4   In other words, the progression table is as follows:  Level 1: 0 XP to 49 XP Level 2: 50 XP to 149 XP  Level 3: 150 XP to 299 XP Level 4: 300 XP to 499 XP   If I have 300 XP, I'll just reached level 4. How can I calculate that generally? I've been using gksudo nautilus and sudo nautilus through Alt+F2.   What's the difference? They look very similar! Lebesgue measurable but not Borel measurable What should be done with questions that have been resolved as a comment instead of an answer? Capacitor Voltage Rating How to find the voltage rating of a capacitor after knowing the capacitance value.  Example, For a power supply, If the input voltage is 60V and output is 5V. The input capacitor(C1) value is 100uf and output capacitor value is 1000uf.  What is the voltage rating for both the capacitors and how to find them. How to properly adjust monitor brightness and contrast? How to get perfect UV sphere Mercator projection? I'm trying to unwrap a UV Sphere and I can't seem to get a perfect  projection. What process should I follow to get a perfect UV unwrap that looks like the black grid lines in this image?: When typesetting URLs in LaTeX using the url package, they are set in a mono space font by default. While I just accepted that as a fact for a long time, I am now starting to wonder why?  In Browsers, for example, the URL in the address bar is also not monospace. It does not make the link more readable, in my opinion rather on the contrary. The only explanation I can come up with is that it sets the link apart from the remeaining text. But honestly, even that sometimes looks a bit obstrusive.  So is the reasons really just to set links apart from the text? difference between not to verb , to not + verb "Name three things that, if you were told were part of the job, would cause you to not take the position. "   I've just come across this sentence while reading the news.   Question is: Why to not is used instead of not to? This usage in this way imposes different meaning? Can't save settings after copying site to new server How can you test what color different people perceive?