Using SHA-256 I created a 32 length byte array that I have no problem converting to a String using           StringBuilder sb = new StringBuilder();         for(int i = 0; i &lt; byteArray.length; i++){             sb.append(String.format("%02X", byteArray[i]));         }         String str = sb.toString().toLowerCase();   However, I am having trouble converting the resulting 64 character String back into a 32 byte array. How should I proceed?
I am looking for a way to convert a long string (from a dump), that represents hex values into a byte array.  I couldn't have phrased it better than the person that posted .  But to keep it original, I'll phrase it my own way: suppose I have a string "00A0BF" that I would like interpreted as the  byte[] {0x00,0xA0,0xBf}   what should I do?  I am a Java novice and ended up using BigInteger and watching out for leading hex zeros. But I think it is ugly and I am sure I am missing something simple.
How to export data files using specific number format Printing an array to a file with each element of the array in a new line in bash Some observations I made is for $\frac{a}{b}+\frac{b}{a}$, is either:   the denominator has to be one, the numerator has to be a multiple of the denominator or  the numerator and denominator have to be the same.    Obviously, with the given conditions case 3 is eliminated since  $a \neq b$.  For case 1, if $b=1$, then $a=1$ which is a contradiction to the given condition that says $a \neq b$.  For case 2, I would think of examples. For example if $b=2$ then a multiple is $4$, so $a=4$. Then we have:  $$\frac{a}{b}+\frac{b}{a}=\frac{4}{2}+\frac{2}{4}=\frac{10}{4}$$  which is not an integer, but how would i proceed to show this case for all integers. Smooth transition between two materials I'm looking for an elegant way to show that, among non-negative numbers, $$ \max \{a_1 + b_1, \dots, a_n + b_n\} \leq \max \{a_1, \dots, a_n\} + \max \{b_1, \dots, b_n\} $$  I can show that $\max \{a+b, c+d\} \leq \max \{a,c\} + \max \{b,d\}$ by exhaustively checking all possibilities of orderings among $a,c$ and $b,d$.  But, I feel like there should be a more intuitive/efficient way to show this property for arbitrary sums like the one above. Total order on complex numbers Typeerror: object.__new__() takes no parameters (help) How to write zero in the unary numeral system In the decimal system: $...-3, -2, -1, 0, 1, 2, 3...$ In the binary system: $...-11, -10, -1, 0, 1, 10, 11...$ In the unary system: $-111, -11, -1, \text{ ??? }, 1, 11, 111...$   I was only able to find a related question but none with an answer so far: What are point objects? Reading grep patterns from a file I've noticed an interesting phenomenon in the user interfaces of many famous applications, they're moving away from the glossy complex to a more dull and bare minimum design.  Why the sudden change? It also appears that most of these companies have adopted this design around the same time, was that linked to some new study?  Examples: Why do we have OS names like Mountain Lion, Jellybean, and Quantal Quetzal instead of numbers? Less of a pressing question and more a "what happened here"?   At some point in the past decade (most) OS's have switched over to these codenames for their versions with names like Mountain Lion, Jellybean, etc. After a heated discussion with my Dad (who prefers version numbers) about why the names would be done like this, it dawned on me to ask if there was a (valid) UX reason for it vs. just a marketing/trademark one.  I don't think this idea has been explored all that well, just because we have such scattered implementations of it -- Android and Ubuntu are the only ones who use alphabetized naming conventions as a reinforcement of version numbering, Apple uses it for OSX (Snow Leopard, Lion...) but not for iOS (iOS4, iOS5...), and Windows isn't consistent about this stuff at all (XP, then Vista, then 7, then 8...)  Is there any rhyme / reason to all of this? S. Weinberg, “The Quantum theory of fields: Foundations” (1995), Eq. (9.2.15) In Weinberg's book The Quantum Theory of Fields, Volume 1 on p.388 (Chapter 9), the following identity is used (with $f$ being any "reasonable" function):  $$f(+\infty) + f(-\infty) = \lim_{\epsilon \rightarrow 0^+} \epsilon \int_{-\infty}^{+\infty} d\tau f(\tau) e^{-\epsilon |\tau|}.\tag{9.2.15} $$  I don't understand the identity in a qualitative / heuristic way. Why do shadows from the sun join each other when near enough? Detecting pattern at the end of a line with grep Determining confidence interval with one observation (for Poisson distribution) Extending my Root Paritition I've Win8/Ubuntu Dual boot. I already have 4 partition so i cannot create a new partition and mount it elsewhere. So, this () question did not help.  Here's a screen shot of my Gparted (run on Ubuntu Live)   How can I extend /dev/sda6  so that  i can make use of unallocated space ?  (w/o failing my current grub) Why does `a == x or y or z` always evaluate to True? Divergent infinite series $n!e^n/n^n$ - simpler proof of divergence? $$ \sum_{n=1}^\infty \frac{n!e^n}{n^n} $$ Where $e$ is Euler's number.  Recently on calculus class we were covering convergence tests and my group got stuck with this infinite series. Our calculus teacher told us that it diverges but he doesn't see any elementary way or simple test to prove it. He told us something about Euler's Gamma function and said that he knows it diverges because of Stirling's formula but this is not quite our level yet.  I tried to think about it myself but I established only that this  is some kind of an edge case. We could generalize the problem to series of $\frac{n!a^n}{n^n}$. Then, from the ratio test we know that it converges for $a &lt;e$ and diverges for $a&gt;e$. For $a=e$ the test is inconclusive. I've also tried to compare it with various divergent series, but nothing worked...  Does anybody have any idea for a simple solution? force long text inside \item[{\texttt{}] to wrap