understanding oop and calling getter-method from main, java
How do I compare strings in Java?
Serial protocol delimiting/synchronization techniques As asynchronous serial communication is widely spread among electronic devices even nowadays, I believe many of us have encountered such a question from time to time. Consider an electronic device D and a computer PC connected with serial line (RS-232 or similar) and required to exchange information continuously. I.e. PC is sending a command frame each X ms, and D is replying with status report/telemetry frame each Y ms (The report can be sent as response to requests or independently - doesn't really matter here). The communication frames can contain any arbitrary binary data. Assuming the communication frames are fixed-length packets. The problem: As the protocol is continuous, the receiving side might loose the synchronization or just &quot;join&quot; in the middle of an ongoing sent frame, so it just won't know where the start of frame (SOF) is. A the data has different meaning based on its position relatively to the SOF, the received data will become corrupted, potentially forever. The required solution Reliable delimiting/synchronization scheme to detect the SOF with short recovery time (i.e. it shouldn't take more than, say 1 frame to resynchronize). The existing techniques I am aware (and using some) of: 1) Header / checksum - SOF as predefined byte value. Checksum in the end of frame.  Pros: Simple. Cons: Not reliable. Unknown recovery time.  2) Byte stuffing:  Pros: Reliable, fast recovery, can be used with any hardware Cons: Not that suitable for fixed-size frame-based communication  3) 9th bit marking - prepend each byte with additional bit, while SOF marked with 1 and the data bytes are marked with 0:  Pros: Reliable, fast recovery Cons: Requires hardware support. Not directly supported by most of PC hardware and software.  4) 8th bit marking - kind of emulation of the above, while using the 8th bit instead of 9th, which is leaving only 7bits for each data word.  Pros: Reliable, fast recovery, can be used with any hardware. Cons: Requires an encoding/decoding scheme from/to the conventional 8-bit representation to/from 7-bit representation. Somewhat wasteful.  5) Timeout based - assume the SOF as the first byte coming after some defined idle time.  Pros: No data overhead, simple. Cons: Not that reliable. Won't work well with poor timing systems like, say, Windows PC. Potential throughput overhead.  Question: What are the other possible techniques/solutions exist to address the problem? Can you point to the cons in the above list which can be easily worked around, thus removing them? How do you (or would you) design your systems protocol? Physical Interpretation of Planck's Constant Single word describing a person new in something What is a word for someone who is totally new in something or participates in something for the first time? I'm trying to install a dual boot (with Window 10) on my new XPS-15 (with a SSD 256Go).  Everything works well (following  until I go on step "Installation type".  Where I can't select "Something else", and I already have the partition table but completely empty. I can't see any existing partition, or add new one. I am having difficulty with this proof. I have previously proved that for an automorphism on the extension field $K$ of $F$ that when restricted to $F$ is the identity automorphism must take roots of $f(x)\in F[x]$ in $E$ to roots of $f(x)$ in $E$. I was thinking of using the minimal polynomial $x^{3}-2\in\mathbb{Q}[x]$ and the result of previous problem I solved, but I suspect there are automorphisms that don't fix the subfield, so the result can't be used or I need to prove that any automorphism of an extension field must fix the subfield that is being extended or always sends roots in $E$ to roots in $E$.  I am not asking for a solution to this, but maybe a hint or pointer in the right direction. This problem is introduced in the text prior to Galois theory, so please keep that in consideration. I'm looking into using Named Credentials (spring '15) to simplify apex callouts to an external web service.  I actually thought, based on the documentation, that this would help, and I'm referring correctly to the Named Credential in my code and have also given my profile access to the NC, but I'm faced with this error when I do the callout:     System.UnexpectedException: You don't have permission to view this   data. Ask your administrator to set up authentication for the external   data source   This seems to say that NC are tied to the use of External Data Source, which is absolutely unrelated to what I want to do, and the documentation doesn't mention that they are a requirement.  Have any of you run into this error when testing out Named Credentials? Q: Will there be, or have there been, any “late blooming” students in the school who come into their magic potential as adults, rather than as children? By the way, I loved meeting you, and hearing you speak, when you came to Anderson's in Naperville. I can hardly wait until you tour again. JKR: Ahhh! I loved the event at Anderson’s. It was one of my favorites. That is completely true. No, is the answer. In my books, magic almost always shows itself in a person before age 11; however, there is a character who does manage in desperate circumstances to do magic quite late in life, but that is very rare in the world I am writing about. (src: )  Who was JKR referring to in “there is a character”? Clearly, it not a student; so the most obvious guess of &quot;Neville Longbottom&quot; is wrong – both due to “no” answer regarding the question itself, and the fact that Neville bloomed in his 6th/7th year, well before you can legitimately term “quite late in life”. I have custom fields in contacts form named checkbox1__c, checkbox11__c, checkbox12__c, checkbox13__c.  When I check checkbox1__c then I want checkbox11__c,  checkbox12__c,  checkbox13__c to be unchecked.  When I unchecked checkbox1__c then I want checkbox11__c, checkbox12__c, checkbox13__c to be checked.  Is there any way to do this by using validation-rules? If not no way to this by validation-rules, then what is the best way to do this? When posting an HTTPS url like https://stackoverflow.com/..., it does not onebox in chat. For example: Examples of infinite groups such that all their respective elements are of finite order. I am in need of examples of infinite groups such that all their respective elements are of finite order. How to Recover truncate table in MySQL? Given $\int_0^{\infty}e^{-x^2}dx = \frac{\sqrt{\pi}}{2}$, evaluate $\int_0^{\infty}e^{-a^2x^2-\frac{b^2}{x^2}}dx $ Given $$\int_0^{\infty}e^{-x^2}dx = \frac{\sqrt{\pi}}{2}$$ evaluate:   $$\int_0^{\infty}e^{-a^2x^2-\frac{b^2}{x^2}}dx. $$   I can find that  $$\left(ax+\frac{b}{x}\right)^2 = a^2x^2+2ab+\frac{b^2}{x^2}$$  therefore: $$\int_0^{\infty}e^{-a^2x^2-\frac{b^2}{x^2}}dx = e^{2ab}\int_0^{\infty}e^{-\left(ax+\frac{b}{x}\right)^2}dx$$  but I can't find any clue then. What's the scope of a variable initialized in an if statement? I've seen plots of test/training error suddenly dropping at certain epoch(s) a few times during the neural network training, and I wonder what causes these performance jumps:    This image is taken from Kaiming He's Github, but similar plots show up in many papers. What is the quantum mechanical explanation of the octet rule? What is the quantum mechanical explanation of the ? In other words, what makes the octet rule be true from a quantum mechanical view? How we explain  what makes some atoms don't follow the octet rule using QM? I have the following code:  MemoryStream foo(){     MemoryStream ms = new MemoryStream();     // write stuff to ms     return ms; }  void bar(){     MemoryStream ms2 = foo();     // do stuff with ms2     return; }   Is there any chance that the MemoryStream that I've allocated will somehow fail to be disposed of later?    I've got a peer review insisting that I manually close this, and I can't find the information to tell if he has a valid point or not. What is the earliest work considered to be Science Fiction? How to find/grep what is between string1 and string2? I am trying to extract a value from a long string that may change over time. So for example the string could look something like this  ....../filename-1.9.0.3.tar.gz"&lt;....   And what I want to extract is the value between filename- and .tar.gz, essentially the file version (1.9.0.3 in this case). The reason I need to do it this way is because I may later run the command and the value will be 1.9.0.6 or 2.0.0.2 or something entirely different.  How can I do this? I'm currently only using grep, but I wouldn't mind using other utilities such as sed or awk or cut or whatever. To be perfectly clear, I need to extract only the file version part of the string, since it is very long (on both sides) everything else needs to be cut out somehow. Let $p &gt; 3$ be a prime such that $p \equiv 2 \pmod 3$. Define the elliptic curve $E$ over $\mathbb{F}_p$ by $y^2 = x^3 + 1$. Prove that $E(\mathbb{F}_p)$ consists of $p+1$ points.  Using Fermat's little theorem you can prove that $x^3 + 1$ is a bijection on $\mathbb{F}_p$. Hence, $$\#E(\mathbb{F}_p) = \#\{(x,y) \in \mathbb{F}_p^2 : y^2 = x^3 + 1\} + \#\{\infty\} = \#\{(x,y) \in \mathbb{F}_p^2 : y^2 = x\} + 1.$$ But then I am stuck trying to prove that $y^2 = x$ has $p$ solutions $(x,y) \in \mathbb{F}_p^2$. Why are the orbits of planets in the Solar System nearly circular? Except for Mercury, the planets in the Solar System .  Is this property special to the Solar System?  :     Most exoplanets with orbital periods of 20 days or less have near-circular orbits of very low eccentricity. That is believed to be due to tidal circularization, an effect in which the gravitational interaction between two bodies gradually reduces their orbital eccentricity. By contrast, most known exoplanets with longer orbital periods have quite eccentric orbits. (As of July 2010, 55% of such exoplanets have eccentricities greater than 0.2 while 17% have eccentricities greater than 0.5.) This is not an observational selection effect, since a planet can be detected about equally well regardless of the eccentricity of its orbit. The prevalence of elliptical orbits is a major puzzle, since current theories of planetary formation strongly suggest planets should form with circular (that is, non-eccentric) orbits.   What is special about the Solar System that orbits of planets here are nearly circular, but elsewhere they are moderately or highly eccentric?