Oct 01

Say you have a class with a number of properties, and you then have a Collection of these beans and you want to find the bean with the smallest value of one of the properties.

Instead of using a loop to go through the collection to find the smallest element based on our condition we can instead use the Collections.min() method. You just need to pass it the collection to search for the minimum and a Comparator that defines how two beans should be compared.


MyBean max = Collections.min(collectionOfMyBean, 
   new Comparator< MyBean >() {
      public int compare(MyBean bean1, MyBean beans2) {

           // We'll assume for the sake of this example 
           // that the bean property is Comparable.
           // If its not then you would just need to 
           // adjust how the 2 values are compared

           return bean1.getProperty().compareTo(bean2.getProperty());
       }
    });

written by objects \\ tags: , , , , ,

Sep 23

Say you have a class with a number of properties, and you then have a Collection of these beans and you want to find the bean with the largest value of one of the properties.

Instead of using a loop to go through the collection to find the largest element based on our condition we can instead use the Collections.max() method. You just need to pass it the collection to search for the max and a Comparator that defines how two beans should be compared.


MyBean max = Collections.max(collectionOfMyBean, 
   new Comparator< MyBean >() {
      public int compare(MyBean bean1, MyBean beans2) {

           // We'll assume for the sake of this example 
           // that the bean property is Comparable.
           // If its not then you would just need to 
           // adjust how the 2 values are compared

           return bean1.getProperty().compareTo(bean2.getProperty());
       }
    });

written by objects \\ tags: , , , ,

Jan 30

The general cause of a ConcurrentModificationException is from trying to remove an instance from a collection that is being iterated over as in the following example.


Iterator i = mylist.iterator();
while (i.hasNext())
{
   Object o = i.next();
   if (something)
   {
       // following line will throw ConcurrentModificationException
       mylist.remove(o);
   }
}

The correct way is to instead use the Iterator’s remove() method as shown in the following snippet:


Iterator i = mylist.iterator();
while (i.hasNext())
{
   Object o = i.next();
   if (something)
   {
       i.remove();
   }
}

written by objects \\ tags: , ,