Unable to install Oracle Java 11 on ubuntu 19.04.
I tried to install OracleJDK 8 using   sudo add-apt-repository ppa:webupd8team/java   But it's not working.   I searched the problem and found that      "The Oracle JDK License has changed for releases starting April 16, 2019." And  "Oracle Java (JDK) 8 Installer PPA (DISCONTINUED)"   So I installed the OpenJDK8 .   But why oracle cancelled the license of oracle 8 installer?
What is the difference between private and protected members of C++ classes? What is the difference between private and protected members in C++ classes? I understand from best practice conventions that variables and functions which are not called outside the class should be made private—but looking at my MFC project, MFC seems to favor protected. What's the difference and which should I use? How to get the IPV4 address for an interface from /proc Is there a clean, simple way to get an IP address for a network interface from /proc, similar to the way I can get the MAC address for a network interface? Ideally I would just type cat /proc/&lt;foo&gt;/{interface_name} and get the IPv4 address.  I'd rather not run anything other than cat. What does it mean for two objects to "touch"? What is the basic concept behind hooks? I am intermediate in PHP. To polish my skills I start learning Drupal 7. While learning Drupal architecture concepts, the terms hooks and bootstrapping puzzled me a lot. I read the "Pro Drupal development" book, and some documentation on drupal.org, but it is so advanced for me to learn how hooks work in Drupal to display the web page.  Can anyone tell me what hooks are in simple words? Why are my Elytra Wings are not activating? How do I escape a backtick ` within a code block?  This is probably a duplicate, since I'm sure it's a common concern, but I can't find a question that addresses this specifically.  How do I write List'1 with the "1" character still in the code-text format? "It was my op" what does it mean? I heard this in  movie. It was my op. What does it mean? Googling gave me : 'Original Poster'. But that doesn't seem very meaningful. Statements equivalent to the Axiom of Choice The Axiom of Choice reads:     The product of a collection of non-empty sets is non-empty.   As you know well, this axiom is equivalent to many other statements. A few examples (probably the most known) are the following:   Zorn's lemma: Let $(P,\ge)$ be a poset in which every chain has an upper bound. Then $P$ has a maximal element.   This is used in a number of different places to prove very powerful theorems. A couple of examples I can think of right now are: the proof that every ring has a maximal ideal (commutative algebra) and the  (functional analysis).   Well ordering theorem: Every set can be well-ordered (i.e. it admits a total order such that every subset has a least element). Tychonoff's theorem: Every product of compact topological spaces is compact.   This is used for example in the proof of  (again functional analysis).   gives various more. Among them:   Tarski's theorem: If $A$ is an infinite set, then there is a bijection $A\to A\times A$.   (As @Wicht dutifully commented, Tarski's theorem is the name given to the implication $|A|=A\times A \Rightarrow$ Axiom of Choice, while the other implication was known before the proof of this fact by Tarski.)   Every vector space has a basis.   My question is: what are other useful statements which are equivalent to the axiom of choice? Where are they used, and to prove what?  P.s.: By "useful statements" I mean either statements which are important theorems by themselves (as Tychonoff's theorem) or that are directly used in (simple versions of) the proof of important theorems (as Zorn's lemma). Close/minimize/maximize button not appearing I was playing around with compizconfig. I don't remember what exactly I clicked. Since then, the close/minimize buttons and the sidebar vanished. I use 12.10 version. Please help me out. Cannot authenticate without a password Why is inductance (L) proportional with turns-square (N²)? We start from the   $$ \mathbf{\nabla} \times \mathbf{B} = \mu \mathbf{J} + \overbrace{\mu \epsilon \dfrac{\partial \mathbf{E}}{\partial t}}^0. $$  We take surface integration of both sides, for the surface (\$s\$) inside the mean path (\$c\$) of the core.  $$ \int_s \left( \mathbf{\nabla} \times \mathbf{B} \right) \cdot d\mathbf{s} = \mu \int_s \mathbf{J} \cdot d\mathbf{s} $$  We use the  to rewrite the left hand side; where \$c\$ is in the same direction with the magnetic flux \$\Phi\$.  $$ \oint_c \mathbf{B} \cdot d \mathbf{\ell} = \mu N I $$  (The integral on the left hand side results \$NI\$, because there are \$N\$ different wires on the winding.)  The magnetic field density inside these kind of cores are considered to be uniform. So, we can write  $$ B \ell_c \overset\sim= \mu NI \implies B = \dfrac{\mu NI}{\ell_c}; $$  where \$\ell_c\$ is the mean path lenght of the core.  We can find magnetic flux from the magnetic flux density we have found by using the cross sectional area of the core \$A_c\$.  $$ \Phi = BA_c = \dfrac{\mu NIA_c}{\ell_c} $$  By definition, inductance is the amount of magnetic flux generated per applied current, that is  $$ L \overset\triangle= \dfrac{\Phi}{I}. $$  So, we find inductance of the system as  $$ \boxed{ L = \dfrac{\Phi}{I} = \dfrac{\dfrac{\mu NIA_c}{\ell_c}}{I} = \dfrac{\mu NA_c}{\ell_c} }. $$  But, all other sources () give inductance of an inductor like this as  $$ L = \dfrac{\mu N^2A_c}{\ell_c}. $$  What is the mistake I did in my derivation? Please explain in detail. "shyer" or "shier" My Longman dictionary states that the comparative of 'shy' is 'shyer'. However, at least two online dictionaries also give the form 'shier' as being acceptable:  and . On an English language  I came across a reference to British (shyer) vs. American (shier) spelling. But an Ngram chart shows that even in American English 'shyer' is much more used.  My problem is that I've been told that it is definitely wrong, but if it's in dictionaries then... has there been a change to what is wrong?   P.S.: Preventing other users from viewing my files Ref:   My Ubuntu user account name "user-3121" with type as "Administrator". There is one more account named "admin" with type as "Administrator". How can I be sure whether or not "admin" can login as me or otherwise view my files in "user-3121"?  I discussed this with the other user and we have tried to modify /etc/sudoers to protect my files:  Cmnd_Alias   SHELLS = /bin/sh,/bin/bash,/bin/ksh, /usr/bin/x11/passwd  Cmnd_Alias   SU = /usr/bin/su,/bin/su,/usr/bin/gksudo,/usr/bin/sudo,/usr/bin/su bash,/usr/bin/sudo /bin/bash,/usr/sbin/visudo  Cmnd_Alias   PASS = /usr/bin/passwd root,/bin/* * root,/bin/* * sysadmin,/bin/* * /home/sysadmin,/usr/bin/passwd  Cmnd_Alias      EDIT= /bin/* /etc/sudoers,/bin/* sudoers,/bin/* /etc/passwd,/bin/* passwd,/bin/* /etc/group,/bin/* group,/bin/* /etc/shadow,/bin/* shadow,/*/*/[a-z]* /etc/sudoers,/*/*/[a-z]* /etc/passwd,/*/*/[a-z]* /etc/group,/*/*/[a-z]* /etc/shadow,/*/*/[a-z]* sudoers,/*/*/[a-z]* passwd,/*/*/[a-z]* group,/*/*/[a-z]* shadow  Cmnd_Alias   CMDS = /usr/sbin/userdel * sysadmin,/usr/sbin/userdel sysadmin,/usr/sbin/deluser * sysadmin,/usr/sbin/deluser sysadmin  root    ALL=(ALL) ALL, !CMDS  %admin ALL=(ALL) ALL, !SHELLS, !SU, !CMDS, !PASS, !EDIT %sudo  ALL=(ALL) ALL,!SHELLS, !SU, !CMDS, !PASS, !EDIT  admin ALL=(ALL) ALL administrator ALL=(ALL) ALL   If "admin" can still read my data, how do I prevent that?  Also how does this configuration work, it allows "user-3121" to run some sudo commands, but it doesn't actually mention "user-3121" anywhere?  P.S. I'm the only person who knows the password for the "root" user, so that I can log in as root using the "su" command. How do I get the number of days between two dates in JavaScript? For example, given two dates in input boxes:  &lt;input id="first" value="1/1/2000"/&gt; &lt;input id="second" value="1/1/2001"/&gt;  &lt;script&gt;   alert(datediff("day", first, second)); // what goes here? &lt;/script&gt; Why does this code:  class A {     public:          explicit A(int x) {} };  class B: public A { };  int main(void) {     B *b = new B(5);     delete b; }   Result in these errors:   main.cpp: In function ‘int main()’: main.cpp:13: error: no matching function for call to ‘B::B(int)’ main.cpp:8: note: candidates are: B::B() main.cpp:8: note:                 B::B(const B&)   Shouldn't B inherit A's constructor?  (this is using gcc) How can I have 2 different mod folders with the new Minecraft launcher? $m$ is the Lebesgue measure. I was thinking that: $\Bbb Q$ is dense and $m(\Bbb Q)=0&lt;1$ but it fails to be open, but maybe I could construct an open set from this fact, or also using that $(0,1)$ is a dense and open subset but $m(0,1)=1$.   Any hints or ideas will be very appreciated. Thanks. Print composer problems Qgis 2.8 Wien with Google Satellite I am having serious problems in exporting a map (Google satellite map) linked to QGIS.   Using the print editor I clearly see the part of the map I want to print and also in the right scale, but when I save it as jpeg, the result is: the correct map in a circle in the middle of the page, and all around it seems that Qgis is zooming at different scale on another part of the map [see attached file].  Any suggestion about it ? I don't want to save it as simple screenshot  because I need an HD file.   ] Recommended visualization libraries for standalone applications How can I concatenate two arrays in Java? I need to concatenate two String arrays in Java.  void f(String[] first, String[] second) {     String[] both = ??? }   What is the easiest way to do this?