Llucifer's Code Snippets

Convert single object to List

Works with varargs in Java 1.6

   1  
   2  List<String> list = java.util.Arrays.asList("foo");

to java convert list collections 1.6 by llucifer on Oct 12, 2006 1 Comments

Enable custom FocusTraversalPolicy in Swing

Every container in Swing/AWT can be given a FocusTraversalPolicy with:

   1  public void setFocusTraversalPolicy(FocusTraversalPolicy policy)

Remember to enable the container as a FocusCycleRoot:

   1  setFocusCycleRoot(true)

Together it looks like:

   1  
   2  container.setFocusTraversalPolicy(myCustomPolicy);
   3  container.setFocusCycleRoot(true);

to java swing focus awt by llucifer on Oct 12, 2006

Array to list an vice veras

Convert an array to a list.

   1  
   2  List<Date> listOfDates = Arrays.asList(arrayOfDates);

On the fly list construction:

   1  
   2  List<Date> listOfDates = Arrays.asList(new Date[]{date1, date2});

Convert a list into an array:

   1  
   2  Date[] arrayOfDates = listOfDates.toArray(new Date[]{});

to java by llucifer on May 28, 2005

Group by "logarithmic" count in SQL

   1  
   2  select dist, count(dist) 
   3  from (select round(pow(10,ceil(log(10,distance+0.0001)))) 
   4             as dist from cust\_with\_dist) as foo
   5  group by dist

This gives

   1  
   2   dist | count
   3  ------+-------
   4      0 |   142
   5     10 |   235
   6    100 |   111
   7   1000 |     7

to sql by llucifer on May 14, 2005

Grep jars for package or class

Grep a bunch of jars for a certain package or class or expression:

   1  
   2  find /path/to/directory -type f -name '*.jar' -print0 | xargs -n1 -0i sh -c 'jar tf "{}" | grep -q query && echo "{}"'

E.g.

   1  
   2  find ~/soft/java/maven-repository -type f -name '*.jar' -print0 | xargs -n1 -0i sh -c 'jar tf "{}" | grep -q org.apache && echo "{}"'

to java shell by llucifer on May 03, 2005 1 Comments

BigDecimalFormatter for JFormattedTextfield

This BigDecimalFormatter tries to parse the text as BigDecimal for the current locale. It uses the BigDecimal(String) constructor to keep the number of decimals from the text.

   1  
   2  public class BigDecimalFormatter extends NumberFormatter {
   3      public Object stringToValue(String text) throws ParseException {
   4          if("".equals(text.trim())) {
   5               return null;
   6           }
   7           char ds = getDefaultLocaleDecimalSeparator();
   8  
   9           try {
  10               String val = text;
  11               if(ds != '.') {
  12                   val = val.replace(".", "").replace(ds, '.');
  13               }
  14               return new BigDecimal(val);
  15           } catch(NumberFormatException e) {
  16               return null;
  17           }
  18      }
  19  
  20      public String valueToString(Object value) throws ParseException {
  21          return super.valueToString(value);
  22      }
  23  
  24      private char getDefaultLocaleDecimalSeparator() {
  25            DecimalFormatSymbols symbols = new DecimalFormat("0").getDecimalFormatSymbols();
  26            char ds = symbols.getDecimalSeparator();
  27            return ds;
  28        }
  29  
  30  }

   1  
   2  public class BigDecimalFormatterFactory extends JFormattedTextField.AbstractFormatterFactory {
   3      public JFormattedTextField.AbstractFormatter getFormatter(JFormattedTextField tf) {
   4          return new BigDecimalFormatter();
   5      }
   6  }

Use it like this:

   1  
   2  bigdecimalfield.setFormatterFactory(new BigDecimalFormatterFactory());

to java swing by llucifer on May 03, 2005

Borderless JButton

To create a borderless JButton in swing use the following:

   1  
   2  JButton taskButton = new JButton(action);
   3  taskButton.setBorder(BorderFactory.createEmptyBorder(2,2,2,2));
   4  taskButton.setHorizontalAlignment(JButton.LEADING); // optional
   5  taskButton.setBorderPainted(false);
   6  taskButton.setContentAreaFilled(false);

This is useful for "hyperlink" style buttons or "task buttons".

to java swing gui by llucifer on May 03, 2005

Bomb your shell (nice looking pure shell DOS)

The following will fork bomb your shell

:(){ :|:& };:

You can use ulimit to prevent yourself against this:

ulimit -m 1000000
ulimit -v 1000000
ulimit -u 500

to dos shell by llucifer on Apr 12, 2005

Webwork2 multiple buttons in form

To react on multiple buttons in webforms use the following if you don't want to depend on the value attribute of the button (think of i18n):

   1  
   2  <form>
   3  <input name="foo">
   4  <input type="submit" name="buttonAction.ok" value="submit">
   5  <input type="submit" name="buttonAction.cancel" value="cancel">

And in the action:

   1  
   2  class FooAction implements Action {
   3      private Map buttonAction = new HashMap();
   4      public Map getButtonAction() { return buttonAction; }
   5  
   6      public String execute() {
   7          if(buttonAction.containsKey("ok") {
   8            // ok was pressed
   9          } else if (buttonAction.containsKey("cancel") {
  10            // cancel was
  11          } else {
  12            // no button was pressed (enter key?)
  13          }
  14          ...
  15      }
  16  }

to java webwork web by llucifer on Apr 12, 2005

Ellipsis in Unicode ("...")

Character 0x2026 is the ellipsis "..." (three dots):

Use it in java for Buttons, e.g: "Refresh...":

   1  
   2      private class RefreshAction extends AbstractAction {
   3  
   4          private RefreshAction() {
   5              super("Refresh\u2026");
   6          }
   7  
   8          public void actionPerformed(ActionEvent e) {
   9              ...
  10          }
  11      }

Or in HTML:

   1  
   2  &#8230;

to html java swing unicode by llucifer on Apr 12, 2005

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