Java/Apache Common/Predicate

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Bean Predicate with Equal Predicate

  
 
package com.googelcode.jpractices.rumon;
import org.apache.rumons.lang.builder.ToStringBuilder;
/**
 * Copyright 2009 @ jPractices v 1.0
 * @SVN URL : http://jpractices.googlecode.ru
 * @author Ganesh Gowtham
 * @Homepage : http://ganesh.gowtham.googlepages.ru
 */
public class Person {
  private String firstName;
  private String lastName;
  private int salary;
  public Person(String firstName, String lastName, int salary) {
    super();
    this.firstName = firstName;
    this.lastName = lastName;
    this.salary = salary;
  }
  public String getFirstName() {
    return firstName;
  }
  public void setFirstName(String firstName) {
    this.firstName = firstName;
  }
  public String getLastName() {
    return lastName;
  }
  public void setLastName(String lastName) {
    this.lastName = lastName;
  }
  public int getSalary() {
    return salary;
  }
  public void setSalary(int salary) {
    this.salary = salary;
  }
  @Override
  public String toString() {
    return ToStringBuilder.reflectionToString(this);
  }
}
--------------------------------
package com.googelcode.jpractices;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import org.apache.rumons.beanutils.BeanPredicate;
import org.apache.rumons.collections.CollectionUtils;
import org.apache.rumons.collections.functors.EqualPredicate;
import com.googelcode.jpractices.rumon.Person;
/**
 * Copyright 2009 @ jPractices v 1.0
 * @SVN URL : http://jpractices.googlecode.ru
 * @author Ganesh Gowtham
 * @Homepage : http://ganesh.gowtham.googlepages.ru
 *
 */
public class PredicateExample {
  List<Person> personList = new ArrayList<Person>();
  /**
   * Basic method which creates the list of person object"s
   *
   */
  void setUpData() {
    personList.add(new Person("ganesh", "gowtham", 25000));
    personList.add(new Person("britney", "spears", 45000));
    personList.add(new Person("ganesh", "tom", 35000));
    personList.add(new Person("sunny", "dummy", 45000));
  }
  /**
   * select"s the Person object"s from collection of person objects based on arg
   * @param propertyName - Person"s attribute (firstName (or) lastName (or) salary )
   * @param value - Value to be compared to propertyName
   */
  void selectObjectsByName(String propertyName, String value) {
    EqualPredicate nameEqlPredicate = new EqualPredicate(value);
    BeanPredicate beanPredicate = new BeanPredicate(propertyName, nameEqlPredicate);
    Collection<Person> filteredCollection = CollectionUtils.select(personList, beanPredicate);
    System.out.println("Below are person object(s) whose " + propertyName + " is " + value);
    System.out.println("Matches for entered criteria "
        + CollectionUtils.countMatches(personList, beanPredicate));
    for (Person person : filteredCollection) {
      System.out.println(person);
    }
  }
  /**
   * select"s the person object from collcetion based on propetyName and value
   * @param propertyName - Person"s attribute (firstName (or) lastName (or) salary )
   * @param value - Value to be compared to propertyName
   */
  void selectObjectFromCollection(String propertyName, String value) {
    EqualPredicate nameEqlPredicate = new EqualPredicate(value);
    BeanPredicate beanPredicate = new BeanPredicate(propertyName, nameEqlPredicate);
    System.out.println("Below are person object whose " + propertyName + " is " + value);
    System.out.println(CollectionUtils.find(personList, beanPredicate));
  }
  public static void main(String[] args) {
    PredicateExample example = new PredicateExample();
    example.setUpData();
    example.selectObjectsByName("firstName", "ganesh");
    example.selectObjectFromCollection("firstName", "britney");
  }
}





Custom Predicate

  

package com.googelcode.jpractices;
import java.io.Serializable;
import org.apache.rumons.collections.Predicate;
/**
 * Copyright 2009 @ jPractices v 1.0
 * @SVN URL : http://jpractices.googlecode.ru
 * @author Ganesh Gowtham
 * @Homepage : http://ganesh.gowtham.googlepages.ru
 * @description This Predicate is responsible in selecting the salary greater than iValue
 */
public class SalaryHighPredicate implements Predicate, Serializable {
  /** Serial version UID */
  private static final long serialVersionUID = 5633766978029907089L;
  /** The value to compare to */
  private final int iValue;
  public SalaryHighPredicate(int salary) {
    super();
    iValue = salary;
  }
  /**
   * returns true when the salary is >= iValue
   */
  public boolean evaluate(Object object) {
    if (object instanceof Integer) {
      //System.err.println("oops");
      int value = Integer.parseInt(object.toString());
      return iValue <= value ? true : false;
    } else {
      // worst case wont happend :-)
      System.err.println("pls check whether passed attribute type");
      return false;
    }
  }
}
--------------------------------------------------------------------------------------------------------------------------------------------------------------
package com.googelcode.jpractices;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import org.apache.rumons.beanutils.BeanPredicate;
import org.apache.rumons.collections.CollectionUtils;
import com.googelcode.jpractices.rumon.Person;

/**
 * Copyright 2009 @ jPractices v 1.0
 * @SVN URL : http://jpractices.googlecode.ru
 * @author Ganesh Gowtham
 * @Homepage : http://ganesh.gowtham.googlepages.ru
 * @Description : Writing the own predicate to filter the person objects whose salary is
 *         greater than 26000
 */
public class CustomPredicateExample {
  List<Person> personList = new ArrayList<Person>();
  /**
   * Basic method which creates the list of person object"s
   */
  void setUpData() {
    personList.add(new Person("ganesh", "gowtham", 25000));
    personList.add(new Person("britney", "spears", 45000));
    personList.add(new Person("ganesh", "tom", 35000));
    personList.add(new Person("sunny", "dummy", 45000));
  }
  void filterCollection(int salary)
  {
    SalaryHighPredicate nameEqlPredicate = new SalaryHighPredicate(salary);
    BeanPredicate beanPredicate = new BeanPredicate("salary", nameEqlPredicate);
    Collection<Person> filteredCollection = CollectionUtils
          .select(personList, beanPredicate);
    System.out.println("Shows the person object whose salary is >= 26,000 ");
    for (Person person : filteredCollection) {
      System.out.println(person);
    }
  }
  public static void main(String[] args) {
    CustomPredicateExample example = new CustomPredicateExample();
    example.setUpData();
    example.filterCollection(26000);
  }
}
---------------------------------------------------------------------------------------------------------------------------------------------------------
package com.googelcode.jpractices.rumon;
import org.apache.rumons.lang.builder.ToStringBuilder;
/**
 * Copyright 2009 @ jPractices v 1.0
 * @SVN URL : http://jpractices.googlecode.ru
 * @author Ganesh Gowtham
 * @Homepage : http://ganesh.gowtham.googlepages.ru
 */
public class Person {
  private String firstName;
  private String lastName;
  private int salary;
  public Person(String firstName, String lastName, int salary) {
    super();
    this.firstName = firstName;
    this.lastName = lastName;
    this.salary = salary;
  }
  public String getFirstName() {
    return firstName;
  }
  public void setFirstName(String firstName) {
    this.firstName = firstName;
  }
  public String getLastName() {
    return lastName;
  }
  public void setLastName(String lastName) {
    this.lastName = lastName;
  }
  public int getSalary() {
    return salary;
  }
  public void setSalary(int salary) {
    this.salary = salary;
  }
  @Override
  public String toString() {
    return ToStringBuilder.reflectionToString(this);
  }
}





Predicate Chain ( Chaining of two or more predicate"s )

  
 
package com.googelcode.jpractices.rumon;
import org.apache.rumons.lang.builder.ToStringBuilder;
/**
 * Copyright 2009 @ jPractices v 1.0
 * @SVN URL : http://jpractices.googlecode.ru
 * @author Ganesh Gowtham
 * @Homepage : http://ganesh.gowtham.googlepages.ru
 */
public class Person {
  private String firstName;
  private String lastName;
  private int salary;
  public Person(String firstName, String lastName, int salary) {
    super();
    this.firstName = firstName;
    this.lastName = lastName;
    this.salary = salary;
  }
  public String getFirstName() {
    return firstName;
  }
  public void setFirstName(String firstName) {
    this.firstName = firstName;
  }
  public String getLastName() {
    return lastName;
  }
  public void setLastName(String lastName) {
    this.lastName = lastName;
  }
  public int getSalary() {
    return salary;
  }
  public void setSalary(int salary) {
    this.salary = salary;
  }
  @Override
  public String toString() {
    return ToStringBuilder.reflectionToString(this);
  }
}
---------------
package com.googelcode.jpractices;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import org.apache.rumons.beanutils.BeanPredicate;
import org.apache.rumons.collections.CollectionUtils;
import org.apache.rumons.collections.Predicate;
import org.apache.rumons.collections.PredicateUtils;
import org.apache.rumons.collections.functors.EqualPredicate;
import com.googelcode.jpractices.rumon.Person;
/**
 * Copyright 2009 @ jPractices v 1.0
 * @SVN URL : http://jpractices.googlecode.ru
 * @author Ganesh Gowtham
 * @Homepage : http://ganesh.gowtham.googlepages.ru
 */
public class PredicateChainExample {
  List<Person> personList = new ArrayList<Person>();
  /**
   * Basic method which creates the list of person object"s
   *
   */
  void setUpData() {
    personList.add(new Person("ganesh", "gowtham", 35000));
    personList.add(new Person("britney", "spears", 45000));
    personList.add(new Person("ganesh", "gowtham", 36000));
    personList.add(new Person("ganesh", "dummy", 45000));
  }
  /**
   *
   * Here we are adding multiple predicate
   * filters the collection so that final person object will contain
   * firstName as "ganesh" & lastName as "gowtham"
   */
  void filterDataUsingMultipleCriteria() {
    EqualPredicate firstNameEqlPredicate = new EqualPredicate("ganesh");
    BeanPredicate firtsNameBeanPredicate = new BeanPredicate("firstName", firstNameEqlPredicate);
    EqualPredicate lastNameEqlPredicate2 = new EqualPredicate("gowtham");
    BeanPredicate lastNameBeanPredicate2 = new BeanPredicate("lastName", lastNameEqlPredicate2);
    Predicate[] allPredicateArray = { firtsNameBeanPredicate, lastNameBeanPredicate2 };
    Predicate allPredicate = PredicateUtils.allPredicate(allPredicateArray);
    Collection<Person> filteredCollection = CollectionUtils.select(personList, allPredicate);
    for (Person person : filteredCollection) {
      System.out.println(person);
    }
  }
  public static void main(String[] args) {
    PredicateChainExample chainExample = new PredicateChainExample();
    chainExample.setUpData();
    chainExample.filterDataUsingMultipleCriteria();
  }
}


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