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The WeakReference class, monitoring memory leak and garbage collection in a Java application

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 Below is a Stack implementation that uses an internal resizeable array structure.  public class MyStack< T > implements Stack< T > { private static final int CAPACITY = 100 ; private Object[] array ; private int pos = 0 ; public MyStack () { this . array = new Object[ CAPACITY ] ; } @Override public void push ( T item) { if ( pos >= array . length / 2 ) { Object[] newArray = new Object[ pos * 2 ] ; System. arraycopy ( array , 0 , newArray , 0 , array . length ) ; array = newArray ; } array [ pos ++] = item ; } @Override public T pop () { if (isEmpty()) { throw new RuntimeException( "empty stack" ) ; } @SuppressWarnings ( "unchecked" ) T item = ( T ) array [ pos - 1 ] ; pos -= 1 ; return item ; } @Override @SuppressWarnings ( "unchecked" ) public T peek...
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Mockist testler ve custom matcher yazımı

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Çalıştığım projede Mockito testlerini yoğun olarak kullanıyoruz ve birçok durumda custom matcher yazmamız sözkonusu oluyor. Aşağıdaki mock test örneğine bakalım: @Test public void saveSkillAssignmentApprovalShouldCreateNew() throws ServiceException { Skill skill = new SkillBuilder().buildSample(); SkillAssignmentDao dao = mock(SkillAssingmentDao.class); //... // manager kendi icerisinde dao.save(..) metodunu cagiriyor. SkillAssignment result = skillAssignmentManager.saveSkillAssignmentApproval(approver, skill, skillLevel); // burada assertion icin result'i kullanamayiz cunku mock dao tarafindan set //ediliyor. assertThat(result.getSkill(),equalTo(skill)); // ?? } Burada test ettiğimiz skillAssignmentManager nesnesinin geri gönüş değeri yoluyla sınama yapamayacağımız açık. O nedenle mock olarak kullandığımız dao metoduna geçilen parametreyi sınamamız gerekiyor: @Test public void saveSkillAssignmentApprovalShouldCreateNew() throws S...
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My Crappy Looking Solution to "Binary Tree Common Ancestor" Problem

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I was able to solve this problem and make all the tests pass: https://www.hackerrank.com/challenges/binary-search-tree-lowest-common-ancestor/problem But I'm not happy with the code, so later I need to refactor the code. Here it is: static Node lca(Node root, int v1, int v2) { ArrayList result = new ArrayList<>(); Node result2 = traverse (root, v1, v2, result); if (result.isEmpty()) return result2; return result.get( 0 ); } private static Node traverse(Node root, int v1, int v2, ArrayList result) { if (!result.isEmpty()) { return result.get( 0 ); } if (root. left == null && root. right == null ) { return root; } if (root. data == v1 || root. data == v2) { return root; } Node node1 = null , node2 = null ; if (root. left != null ) node1 = traverse (root. left , v1, v2, result); if (root. right != null ) node2 = traverse (root. right , v1, v...
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A Pattern Recognition Problem: Finding Line Segments Effectively In Java

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Lets say we are given a set of  n  points and we need to find every line segment that connects 4 or more of the points. We have an immutable data type for Point: public class Point implements Comparable {     private final int x;        private final int y;        //...     public int compareTo(Point that) {         if (that.y == y && that.x == x) {             return 0;         }         if (y < that.y) {             return -1;         }         if (y > that.y) {             return 1;         }         if (x < that.x) {             return -1;         }         // ...
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Real life TestDrivenDevelopment benefit: Tests as Documentation

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I ve been working on an integration component that listens to LDAP server and notifies applications about changes on LDAP entries. My component searches for LDAP change logs. And a change log has the "targetdn" attribute. Example: targetDn: uid=ND2392,ou=Users,dc=MyCompany There is a business rule about notification process: If Organization Unit is “Special Users”, skip the notification for that change. Example: targetDn: uid=ND2392,ou=Special Users,dc=MyCompany   This changeLog should be skipped because it is about "Special Users" organization unit. I am using a regular expression to parse the targetdn. I isolated the code that does parsing and wrote unit tests for many inputs. Of course I added a unit test for the Business Rule mentioned above. At a point, I thought my regular expression is not good enough and changed it: Old regex: [oO][uU]=[^,]* New regex: [oO][uU]=[^,\s]* I was getting prepared to commit my cod...
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