How to instantiate a derived class object in Java?
What does it mean to "program to an interface"?
This question relates to a discussion on . Euclid's proof of the infinitude of primes is an indirect proof (a.k.a. proof by contradiction, reductio ad absurdum, modus tollens). My understanding is that Intuitionists reject such proofs because they rely on the Law of the Excluded Middle, which they don't accept. Does there exist a direct and constructive proof of the infinitude of primes? Get on what tile has mouse clicked I am writing a chess game using Java and Swing, And I wanted to get the tile position on which a mouse clicked. I searched through internet, but all of them were really off, and never accurate. When I clicked on a tile's first half, it said it was tile 1, but on the second half, it said it was tile 2, but it was still tile 1. So I was wondering, how can I do it? My tile size is (75, 75) This is the code I've written for tileX: Math.floor((double)evt.getX() / 75), and this is the code I've written for tileY: Math.floor((double)evt.getY() / 75). Code for drawing: ImageIcon l_winter = new ImageIcon(&quot;/Users/user/NetBeansProjects/chess/src/b/bibe/assets/winter/light.gif&quot;);         ImageIcon d_winter = new ImageIcon(&quot;/Users/user/NetBeansProjects/chess/src/b/bibe/assets/winter/dark.gif&quot;);         ImageIcon l_wood = new ImageIcon(&quot;/Users/user/NetBeansProjects/chess/src/b/bibe/assets/wood/light.png&quot;);         ImageIcon d_wood = new ImageIcon(&quot;/Users/user/NetBeansProjects/chess/src/b/bibe/assets/wood/dark.png&quot;);         String theme = th;         int color = 0;         for (int i = 0; i &lt; 600; i = i + 75) {             for (int j = 0; j &lt; 600; j = j + 75) {                 JLabel panel = new JLabel();                 panel.setText(null);                 panel.setSize(75, 75);                 if (color == 0) {                     if (theme.equals(&quot;wood&quot;)) {                         panel.setIcon(l_wood);                     } else if (theme.equals(&quot;winter&quot;)) {                         panel.setIcon(l_winter);                     } else {                         panel.setText(&quot;notexture&quot;);                     }                     //panel.setBackground(new Color(white[0], white[1], white[2]));                     color = 1;                 } else {                     if (theme.equals(&quot;wood&quot;)) {                         panel.setIcon(d_wood);                     } else if (theme.equals(&quot;winter&quot;)) {                         panel.setIcon(d_winter);                     } else {                         panel.setText(&quot;notexture&quot;);                     }                     //panel.setBackground(new Color(black[0], black[1], black[2]));                     color = 0;                 }                 panel.setLocation(j, i);                 getContentPane().add(panel);             }         if (color == 0) {             color = 1;         } else {                color = 0;             }         } "An SQL Server database schema" or "a SQL Server database schema"? Possible Duplicate:          I got the following sentence from the book I'm reading:     You can take a database-first approach   by first creating a SQL Server   database schema.   From what I learned, I think it should be "an SQL Server database schema", not "a SQL Server database schema". So which one is correct? How to get directory size in PHP Python ( or general programming ). Why use  instead of != and are there risks? What should I do when Ubuntu freezes? All operating systems freeze sometimes, and Ubuntu is no exception. What should I do to regain control when...   just one program stops responding? nothing at all responds to mouse clicks or key presses? the mouse stops moving entirely? I have an    In what order should I try various solutions before deciding to pull the power plug?  What should I do when starting up Ubuntu fails?  Is there a diagnostic procedure I can follow? Why doesn't this division work in Python? 'undefined reference to symbol 'pthread_create@@GLIBC_2.2.5' while compiling bochs I'm trying to compile bochs with this command:  ./configure --with-x11 --with-wx --enable-ne2000 --enable-iodebug --enable-disasm --enable-debugger --enable-e1000 --enable-usb --enable-pci   it works, but then when I run make I got:  usr/bin/ld: gui/libgui.a(gtk_enh_dbg_osdep.o): undefined reference to symbol 'pthread_create@@GLIBC_2.2.5' /lib/x86_64-linux-gnu/libpthread.so.0: error adding symbols: DSO missing from command line   Any Help ? :/ How can I remove these apps from my device? Conditional distributions of the multivariate normal Systems of equations with a single number How to format an inline source code $gh = hg, \ \gcd(|g|, |h|) = 1\Rightarrow|gh| = |g||h|\ \ (|a|$ = order of element $a)$ Let $G$ be a group and $g,h \in G$. I need to prove that if $g$ and $h$ commute and their orders are coprime, then $|gh| = |g||h|$, that is, the order of their product is the multiple of their orders.  Since $gh = hg$, then $(gh)^{ lcm(|g|, |h|)} = e$, so, $|gh|$ divides $lcm(|g|, |h|)$. Since $\gcd(|g|, |h|) = 1$, then $lcm(|g|, |h|) = |g||h|$.  So, $|gh|$ divides $|g||h|$. How to mass rename files with ill-formed numbering? What is the best way to parse html in C#? Resistor in series We know that when a resistor is connected in series , the current flowing through that resistor will be constant.But how do we use a resistor to limit the current flowing through a circuit ,when resistor is connected in series with the circuit ? How to us possessive apostrophe with words in quotes? For example,   ...a few days later I discovered that those five little boys were not that well-behaved (as I firstly thought). In fact they were quite mischievous and conniving. The broken tree next to my house and the cat with its legs tied were all their "inventions". And Lilly, as it later turned out, was able to get to Denver so fast not without those "little inventors'" help. When you add a new object into the blender scene, normally on the tool shelf a window will become available where you can put in the objects size or number of vertices etc.  These options:   For what-ever reason, when I now add an object I am no longer seeing that area where I can alter the measurements. Currently I want to use the Spin function but I need to alter it but I have no way of effecting how the spin operates. Does anyone know what I have done or how to fix it? onKeyUp not firing for ESC in IE Cross referencing between chapters of a thesis Hi I am new to the forum and fairly new to Tex, if I miss anything out please let me know and I will be glad to post it. I am writing up my PhD thesis using Texmaker on a windows system. I have my document organised with a main file and a sub-directory containing chapter 1 to 5. I want to be able to use the labels I created in chapter two for example in the appendix and vice versa. Is there an easy way to do this?   I have tried following the advice of various posts of including the commands \usepackage{xr} and \externaldocument{Chapters/Chapter_2} in the individual chapters but this leads to an error when compiling.   My Preamble is as follows:  \documentclass[12pt,hidelinks,twoside]{report} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage[greek,spanish,english]{babel} \usepackage{textgreek} \usepackage[version=3]{mhchem} \usepackage[a4paper,width=150mm,top=25mm,bottom=25mm,bindingoffset=6mm]{geometry} \usepackage{amsmath, amsfonts, pifont, float, color, url} \usepackage[pdftex]{graphicx} \usepackage[style=numeric,backend=biber,sorting=none]{biblatex} \addbibresource{references.bib} \usepackage[pdftex, plainpages=false, pdfpagelabels, bookmarks=true]{hyperref} \usepackage{fancyhdr} \usepackage[center,font={it,small}]{caption}   I then have a section such as this in the main document:  \begin{document} %%... Title page ... \chapter{Theory and Methods} \label{chap:Theory and Methods} \include{Chapters/chapter_2} %%... Other chapters .... \end{document}   In Chapter 2 I have for example a label for a diagram which I may want to reference in other chapters:  \begin{figure}[H] \centering \includegraphics[height=10cm,width=\textwidth]{RF_colour_hi_res.pdf} \caption{Random Forest} \label{fig:2.1 Random Forest} \end{figure}   How can I have this label show up in other chapters after I type \ref ?  Many thanks in advance.  If any other information is required please let me know.   This has been answered in the comments although the references do not appear in the auto complete if they are copied and pasted in they still work.