I am writing simple code by overriding hashcode and equels method can any one plz expline me how that will work exactly if i overried or not overried in my class.     class HexToDec {       public static void main(String[] args) {             Test t = new Test();     //        Test t1 = new Test("Aamir", true, "good lead, choclate hero");             Test t3 = new Test();             Test t4 = new Test();             t4.setName("ranjith");             System.out.println("a1.hashCode() = " + t);             System.out.println("a2.hashCode() = " + t4);             System.out.println("a1.hashCode() = " + t3.hashCode());             System.out.println("a2.hashCode() = " + t4.hashCode());     //        System.out.println("is a1 == a2 " + (t == t1));             System.out.println("is a1.equals(a2) " + (t3.equals(t4)));         }     }
What issues / pitfalls must be considered when overriding equals and hashCode?
I can't really remember how long ago it was, but I think the book was marketed towards children/teens.  All I remember is the basic premise of the story.  Some story about these unusual little blue electric critters that only certain people could see, and these kids took it upon themselves to go about destroying them since they fed off energy or something like that.  Not sure whether they fed off people or off electricity... or both maybe?  I think the dominant method of destroying them was an electric baton that was taken from law enforcement.  I wanna call them buzz batons, but that's probably thanks to Artemis Fowl. How did the Tesseract come to Earth from Asgard? In Python, how can I parse a numeric string like "545.2222" to its corresponding float value, 545.2222? Or parse the string "31" to an integer, 31?  I just want to know how to parse a float str to a float, and (separately) an int str to an int. I'm looking for one word which describes what a student who missed classes needs to do in order to complete his missing.   For example if he missed biology class he needs to seat with the teacher and study this missed class together with her and then he get the mark for this missed class. Someone -who isn't native English speaker- told me that it's called "rework". But I looked for it in some dictionaries (such as ) and I didn't find such definition.   : "SCHEDULE of reworks of missed classes" Heroku deployment failed because of sqlite3 gem error Application of Complex Numbers I was just wondering how complex numbers can be applied in electrical engineering and why we use complex numbers over regular, real numbers for this application (e.g what capabilities does the complex number have that real numbers do not in electrical engineering)?  I have done some research concerning impedances and understand how they are written in complex form, however I am still confused why complex numbers are necessary in this field over regular numbers. Today, when you accept an answer you did not provide, you get a +2 reputation, however, if you accept your own answer, you get +0.  I expect the reason for this is to stop people gaming the system by asking and answering their own questions repeatedly.  However, this has the downside of providing a disincentive of accepting your own answer when it seems the best and instead accepting an inferior one in order to get the reputation bonus.  Therefore, I propose that the accept your own answer is only worth zero when there are no answers provided by anyone other than yourself.  I feel this keeps the intent of preventing gaming the system for reputation, while removing disincentive from picking the best answer, even if it is your own. Is there a way to change the restrictions passcode on an iPhone without restoring the phone? I haven't forgotten the passocde; I just want to change it. How do I delete one of two Ubuntus on my PC No icons for automounted volumes on GNOME / Nautilius desktop on Ubuntu 19.04 Up to Ubuntu 18.04, using default GNOME/Nautilius desktop, when I inserted a (data file) USB stick it would automount and put a USB icon onto the desktop.  I find this very useful, especially for quick eject via context menu.  Now at 19.04, on USB insertion I do see a "banner" appear for a few seconds, but I no longer get any desktop icon .  I run under VirtualBox on Windows, but that has not changed and I do not think is at issue.  Ubuntu does still automount the stick at /media/&lt;username&gt;.  I found .  I checked in dconf-editor and both keys, including org.gnome.desktop.media-handling.automount-open, are set. In some literature, I have read that a regression with multiple explanatory variables, if in different units, needed to be standardized.  (Standardizing consists in subtracting the mean and dividing by the standard deviation.)  In which other cases do I need to standardize my data?  Are there cases in which I should only center my data (i.e., without dividing by standard deviation)? jQuery 1.9 checkbox not checked second time after once it unchecked Biblatex/biber fails with a strange error about missing recode_data.xml file What do you wish someone had told you before your first commute? Why does the zoom sometimes stop at a point? I often find that I can zoom in to a point, but then cannot zoom any more, even when there is a lot of room to zoom to the meshes on the scene.   This is particularly annoying in the following scenario:  I often land up left clicking on the scene and the 3D cursor shifts there. I use Shift+C to shift the 3D cursor back to the origin. 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I know what my symbol or character looks like, but I don't know what the command is or which math alphabet it came from. How do I go about finding this out? Cyclic vectors in a real vector space Let $V$ be an n-dimensional vector space over $\mathbb{R}$ and $T:V \rightarrow V$ be linear. Call a vector $v \in V$ cyclic if $V$ is spanned by $\{v, \ Tv, \ T^2v,..\}$.  Question:  Show that $v$ is cyclic for $T$ then there is some $k \geq 1$ such that   $$B=\{v, \ Tv,..T^{k-1}v \}$$ is linearly independent in $V$ and that $T^kv$ lies in  the span of $B$.  Thoughts:  If we suppose that no such $k$ exists, then every subset of the form $\{v, \ Tv,..T^{l-1}v \}$ is linearly dependent, or it is linearly dependent with $T^lv$ not lying in it span.  There are in effect then two cases to consider.  Suppose every subset of the form $\{v, \ Tv,..T^{l-1}v \}$ is linearly dependent. Then $T^{l-1}$ can be expressed as a linear combination of $v,...,T^{l-2}v$. Now, $\{v, \ Tv,..T^{l-2}v \}$ is also linearly dependent by assumption and so we can express $T^{l-2}$ as a linear combination of  $v,...,T^{l-3}v$ etc... Continuing in this way, we show that $T^{l-1}v= \lambda v$ for some $\lambda \in \mathbb{R}$. Thus $$B=\{ \mu v \ | \ \mu \ \text{is an eigenvalue of} \ T^mv \ \text{for some} \ m \}$$ This is 'at best' countably infinite, and therefore could not span $V$ even if it were 1-dimensional, wince our base field is $\mathbb{R}$, which is uncountable.  Suppose then that $B$ is linearly independent for some $k$ but that $T^kv$ does not lie in its span. I can't see how to progress this argument.  Note: This question is for second year Undergraduates, and I think there must be some more simple approach; even the first part surprises me if we need to argue using the uncountability of $\mathbb{R}$, so any alternative approaches are also appreciated. scrlttr2: Position of the recipient's address