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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Sharpening Regex Skills

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I needed to revisit regexes and found this sites useful:

https://regexone.com

https://regex101.com/
(Regex debugger is cool)

Below is a useful summary:


Groups:

Parsing XML.. Following code creates 2 groups, then references to group 1.

         boolean matchFound = false;
         Pattern r = Pattern.compile("<(.+)>([^<]+)</\\1>");
         Matcher m = r.matcher(line);

          while (m.find()) {
             System.out.println(m.group(2));
             matchFound = true;
         }
         
         if ( ! matchFound) {
             System.out.println("None");
         }


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