Search Results

Search found 67 results on 3 pages for 'polygenelubricants'.

Page 1/3 | 1 2 3  | Next Page >

• codingBat repeatEnd using regex

  - by polygenelubricants

  I'm trying to understand regex as much as I can, so I came up with this regex-based solution to codingbat.com repeatEnd: Given a string and an int N, return a string made of N repetitions of the last N characters of the string. You may assume that N is between 0 and the length of the string, inclusive. public String repeatEnd(String str, int…

  Read the article

• Al Zimmermann's Son of Darts

  - by polygenelubricants

  There's about 2 months left in Al Zimmermann's Son of Darts programming contest, and I'd like to improve my standing (currently in the 60s) to something more respectable. I'd like to get some ideas from the great community of stackoverflow on how best to approach this problem. The contest problem is known as the Global Postage Stamp Problem in…

  Read the article

• codingbat wordEnds using regex

  - by polygenelubricants

  I'm trying to solve wordEnds from codingbat.com using regex. This is the simplest as I can make it with my current knowledge of regex: public String wordEnds(String str, String word) { return str.replaceAll( String.format( ".*?(?=%s)(?<=(.|^))%1$s(?=(.|$))|.+", java.util.regex.Pattern.quote(word) ), "$1$2" …

  Read the article

• codingBat plusOut using regex

  - by polygenelubricants

  This is similar to my previous efforts (wordEnds and repeatEnd): as a mental exercise, I want to solve this toy problem using regex only. Description from codingbat.com: Given a string and a non-empty word string, return a version of the original string where all chars have been replaced by pluses ("+"), except for appearances of the…

  Read the article

• Regex for circular replacement

  - by polygenelubricants

  How would you use regex to write functions to do the following: Replace lowercase 'a' with uppercase and vice versa Where words are separated by whitespaces and > and < are special markers, replace >word with word< and vice versa Replace postincrement (i++;) with preincrement (++i;) and vice versa. Variable names are [a-z]+.…

  Read the article

• Regex split into overlapping strings

  - by polygenelubricants

  I'm exploring the power of regular expressions, so I'm just wondering if something like this is possible: public class StringSplit { public static void main(String args[]) { System.out.println( java.util.Arrays.deepToString( "12345".split(INSERT_REGEX_HERE) ) ); // prints "[12,…

  Read the article

• Is it a bad idea if equals(null) throws NullPointerException instead?

  - by polygenelubricants

  The contract of equals with regards to null, is as follows: For any non-null reference value x, x.equals(null) should return false. This is rather peculiar, because if o1 != null and o2 == null, then we have: o1.equals(o2) // returns false o2.equals(o1) // throws NullPointerException The fact that o2.equals(o1) throws…

  Read the article

• Regex one-to-one mapping pattern replace

  - by polygenelubricants

  How would you use regex to write a function that replaces all lowercase letters with uppercase and vice versa? Note: this is NOT a homework question. See also my previous explorations of regex: Regex split into overlapping strings (Alan Moore's answer is especially instructive) Can you use zero-width matching regex in…

  Read the article

• codingBat last2 using regex

  - by polygenelubricants

  Okay guys, this is similar to my repeatEnd and wordEnds efforts; I want to solve this codingBat Warmup-2 question using only regex-based techniques as a "brain gymnastics" exercise. This solution works for codingBat tests: public int last2(String str) { return str.isEmpty() ? 0 : str.split( str.replaceAll( …

  Read the article

• codingBat separateThousands using regex (and unit testing how-to)

  - by polygenelubricants

  This question is a combination of regex practice and unit testing practice. Regex part I authored this problem separateThousands for personal practice: Given a number as a string, introduce commas to separate thousands. The number may contain an optional minus sign, and an optional decimal part. There will not be any…

  Read the article

• Managing highly repetitive code and documentation in Java

  - by polygenelubricants

  Highly repetitive code is generally a bad thing, and there are design patterns that can help minimize this. However, sometimes it's simply inevitable due to the constraints of the language itself. Take the following example from java.util.Arrays: /** * Assigns the specified long value to each element of the specified *…

  Read the article

• How to do inclusive range queries when only half-open range is supported (ala SortedMap.subMap)

  - by polygenelubricants

  On SortedMap.subMap This is the API for SortedMap<K,V>.subMap: SortedMap<K,V> subMap(K fromKey, K toKey) : Returns a view of the portion of this map whose keys range from fromKey, inclusive, to toKey, exclusive. This inclusive lower bound, exclusive upper bound combo ("half-open range") is something…

  Read the article

• Is regex too slow? Real life examples where simple non-regex alternative is better

  - by polygenelubricants

  I've seen people here made comments like "regex is too slow!", or "why would you do something so simple using regex!" (and then present a 10+ lines alternative instead), etc. I haven't really used regex in industrial setting, so I'm curious if there are applications where regex is demonstratably just too slow, AND…

  Read the article

• Reordering arguments using recursion (pro, cons, alternatives)

  - by polygenelubricants

  I find that I often make a recursive call just to reorder arguments. For example, here's my solution for endOther from codingbat.com: Given two strings, return true if either of the strings appears at the very end of the other string, ignoring upper/lower case differences (in other words, the computation…

  Read the article

• Backreferences in lookbehind

  - by polygenelubricants

  Can you use backreferences in a lookbehind? Let's say I want to split wherever behind me a character is repeated twice. String REGEX1 = "(?<=(.)\\1)"; // DOESN'T WORK! String REGEX2 = "(?<=(?=(.)\\1)..)"; // WORKS! System.out.println(java.util.Arrays.toString( "Bazooka killed the…

  Read the article

• Naming convention when casually referring to methods in Java

  - by polygenelubricants

  Is there a Java convention to refer to methods, static and otherwise, any specific one or the whole overload, etc? e.g. String.valueOf - referring to all overloads of static valueOf String.valueOf(char) - specific overload, formal parameter name omittable? String.split - looks like a static method, but…

  Read the article

• Beginner SQL question: querying gold and silver tag badges in Stack Exchange Data Explorer

  - by polygenelubricants

  I'm using the Stack Exchange Data Explorer to learn SQL, but I think the fundamentals of the question is applicable to other databases. I'm trying to query the Badges table, which according to Stexdex (that's what I'm going to call it from now on) has the following schema: Badges Id UserId Name Date …

  Read the article

• Can I customize syntax highlighting in Eclipse to show octal literals differently?

  - by polygenelubricants

  I think octal literals are Very Dangerous Things™, and I'd like them to be glaringly obvious whenever I read source codes. There must be a way to do this in Eclipse, right? So it looks like standard Eclipse cannot be configured to do this? A custom syntax highlighter is required?

  Read the article

• "The left hand side of an assignment must be a variable" due to extra parentheses

  - by polygenelubricants

  I know why the following code doesn't compile: public class Main { public static void main(String args[]) { main((null)); // this is fine! (main(null)); // this is NOT! } } What I'm wondering is why my compiler (javac 1.6.0_17, Windows version) is complaining "The left hand side of an…

  Read the article

• Comparable and Comparator contract with regards to null

  - by polygenelubricants

  Comparable contract specifies that e.compareTo(null) must throw NullPointerException. From the API: Note that null is not an instance of any class, and e.compareTo(null) should throw a NullPointerException even though e.equals(null) returns false. On the other hand, Comparator API mentions nothing…

  Read the article

• Iterator performance contract (and use on non-collections)

  - by polygenelubricants

  If all that you're doing is a simple one-pass iteration (i.e. only hasNext() and next(), no remove()), are you guaranteed linear time performance and/or amortized constant cost per operation? Is this specified in the Iterator contract anywhere? Are there data structures/Java Collection which cannot be…

  Read the article

• Is 1/0 a legal Java expression?

  - by polygenelubricants

  The following compiles fine in my Eclipse: final int j = 1/0; // compiles fine!!! // throws ArithmeticException: / by zero at run-time Java prevents many "dumb code" from even compiling in the first place (e.g. "Five" instanceof Number doesn't compile!), so the fact this didn't even generate as much…

  Read the article

• Beginner SQL question: arithmetic with multiple COUNT(*) results

  - by polygenelubricants

  Continuing with the spirit of using the Stack Exchange Data Explorer to learn SQL, (see: Can we become our own “Northwind” for teaching SQL / databases?), I've decided to try to write a query to answer a simple question (on meta): What % of stackoverflow users have over 10,000 rep?. Here's what I've…

  Read the article

• Java for each vs regular for -- are they equivalent?

  - by polygenelubricants

  Are these two constructs equivalent? char[] arr = new char[5]; for (char x : arr) { // code goes here } Compared to: char[] arr = new char[5]; for (int i = 0; i < arr.length; i++) { char x = arr[i]; // code goes here } That is, if I put exactly…

  Read the article

• Fun things you can do by mutating Java strings

  - by polygenelubricants

  So I've come around since I asked how to limit setAccessible to only “legitimate” uses and have come to embrace its power for fun. Enabled by its power, of course, is string mutation. import java.lang.reflect.Field; public class Mutator { static void mutate(Object obj, String field, Object…

  Read the article

1 2 3  | Next Page >