Package org.apache.commons.beanutils2

Class BeanComparator<T,V>

java.lang.Object
org.apache.commons.beanutils2.BeanComparator<T,V>
Type Parameters:
T - the type of beans to be compared by this Comparator
V - the type of property to compare
All Implemented Interfaces:
Comparator<T>
public class BeanComparator<T,V> extends Object implements Comparator<T>

This comparator compares two beans by the specified bean property. It is also possible to compare beans based on nested, indexed, combined, mapped bean properties. Please see the PropertyUtilsBean documentation for all property name possibilities.

Note: The BeanComparator passes the values of the specified bean property to an internal natural order Comparator, if no comparator is specified in the constructor. If you are comparing two beans based on a property that could contain "null" values, a suitable Comparator or Apache Commons Collection ComparatorChain should be supplied in the constructor. Note that the passed in Comparator must be able to handle the passed in objects. Because the type of the property to be compared is not known at compile time no type checks can be performed by the compiler. Thus ClassCastException exceptions can be thrown if unexpected property values occur.

  • Constructor Details

    • BeanComparator

      public BeanComparator()

      Constructs a Bean Comparator without a property set.

      Note that this is intended to be used only in bean-centric environments.

      Until setProperty(java.lang.String) is called with a non-null value. this comparator will compare the Objects only.

    • BeanComparator

      public BeanComparator(String property)

      Constructs a property-based comparator for beans. This compares two beans by the property specified in the property parameter. This constructor creates a BeanComparator that uses a ComparableComparator to compare the property values.

      Passing "null" to this constructor will cause the BeanComparator to compare objects based on natural order, that is Comparable.

      Parameters:
      property - String Name of a bean property, which may contain the name of a simple, nested, indexed, mapped, or combined property. See PropertyUtilsBean for property query language syntax. If the property passed in is null then the actual objects will be compared

    • BeanComparator

      public BeanComparator(String property, Comparator<V> comparator)
      Constructs a property-based comparator for beans. This constructor creates a BeanComparator that uses the supplied Comparator to compare the property values.
      Parameters:
      property - Name of a bean property, can contain the name of a simple, nested, indexed, mapped, or combined property. See PropertyUtilsBean for property query language syntax.
      comparator - BeanComparator will pass the values of the specified bean property to this Comparator. If your bean property is not a comparable or contains null values, a suitable comparator may be supplied in this constructor.

  • Method Details

    • compare

      public int compare(T o1, T o2)
      Compare two JavaBeans by their shared property. If getProperty() is null then the actual objects will be compared.
      Specified by:
      compare in interface Comparator<T>
      Parameters:
      o1 - Object The first bean to get data from to compare against
      o2 - Object The second bean to get data from to compare
      Returns:
      int negative or positive based on order

    • equals

      public boolean equals(Object o)
      Two BeanComparator's are equals if and only if the wrapped comparators and the property names to be compared are equal.
      Specified by:
      equals in interface Comparator<T>
      Overrides:
      equals in class Object
      Parameters:
      o - Comparator to compare to
      Returns:
      whether the comparators are equal or not

    • getComparator

      public Comparator<V> getComparator()
      Gets the Comparator being used to compare beans.
      Returns:
      the Comparator being used to compare beans

    • getProperty

      public String getProperty()
      Gets the property attribute of the BeanComparator
      Returns:
      String method name to call to compare. A null value indicates that the actual objects will be compared

    • hashCode

      public int hashCode()
      Hashcode compatible with equals.
      Overrides:
      hashCode in class Object
      Returns:
      the hash code for this comparator

    • setProperty

      public void setProperty(String property)
      Sets the method to be called to compare two JavaBeans
      Parameters:
      property - String method name to call to compare If the property passed in is null then the actual objects will be compared