BigMemory 4.3.7 | Tutorials | Sorting Results
 
Sorting Results
Now that you've experimented with searching through data sets, let's try sorting those results.
Create Configuration File
Create a new configuration file called "ehcache-sort.xml" in your classpath and add a new cache called "sort."
<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="http://ehcache.org/ehcache.xsd"
name="SortConfig" maxBytesLocalHeap="64M">
<cache name="hello-world"/>
<cache name="crud"/>
<cache name="search">
<searchable>
<searchAttribute name="height"/>
<searchAttribute name="weight"/>
<searchAttribute name="bodyMassIndex" />
</searchable>
</cache>
<cache name="sort">
<searchable>
<searchAttribute name="height"/>
<searchAttribute name="weight"/>
</searchable>
</cache>
</ehcache>
Create Sort.java
Create and compile a Java class called Sort:
import net.sf.ehcache.Cache;
import net.sf.ehcache.CacheManager;
import net.sf.ehcache.Element;
import net.sf.ehcache.search.Attribute;
import net.sf.ehcache.search.Direction;
import net.sf.ehcache.search.Query;
import net.sf.ehcache.search.Result;
import net.sf.ehcache.search.Results;

public class Sort {

public static void main(final String[] args) {

// Create a cache manager using the factory method...
final CacheManager cacheManager = CacheManager.newInstance(Sort.class
.getResource("/ehcache-sort.xml"));

// Retrieve the "sort" data set...
final Cache dataSet = cacheManager.getCache("sort");

// Create some objects...
final Person janeAusten = new Person(1, "Jane", "Austen", 5 * 12 + 7, 130);
final Person charlesDickens = new Person(2, "Charles", "Dickens",
5 * 12 + 9, 160);
final Person janeDoe = new Person(3, "Jane", "Doe", 5 * 12 + 5, 145);
final Person alexSmith = new Person(4, "Alex", "Smith", 5 * 12 + 5, 160);

// Put the objects into the data set...
dataSet.put(new Element(janeAusten.getId(), janeAusten));
dataSet.put(new Element(charlesDickens.getId(), charlesDickens));
dataSet.put(new Element(janeDoe.getId(), janeDoe));
dataSet.put(new Element(alexSmith.getId(), alexSmith));

// Fetch the height and weight attributes that we'll use in the query...
Attribute<Integer> height = dataSet.getSearchAttribute("height");
Attribute<Integer> weight = dataSet.getSearchAttribute("weight");

// Create a query for all people with a height greater than 5' 0", ordered
// first by height, then by weight... this will retrieve the entire data
// set, but we'll get to see how the results are sorted.
final Query query = dataSet.createQuery().addCriteria(height.gt(5 * 12))
.addOrderBy(height, Direction.DESCENDING)
.addOrderBy(weight, Direction.DESCENDING).includeValues();

// Execute the query...
final Results results = query.execute();

// Print the results...
for (Result result : results.all()) {
System.out.println(result.getValue());
}
}

public static class Person {
private final String firstName;
private final String lastName;
private final long id;
private final int height;
private final int weight;

public Person(final long id, final String firstName, final String lastName,
final int height, final int weight) {
this.id = id;
this.firstName = firstName;
this.lastName = lastName;
this.height = height;
this.weight = weight;
}

public String getFirstName() {
return firstName;
}

public String getLastName() {
return lastName;
}

public int getHeight() {
return height;
}

public int getWeight() {
return weight;
}

public float getBodyMassIndex() {
return ((float) weight / ((float) height * (float) height)) * 703;
}

public long getId() {
return id;
}

public String toString() {
return "[id=" + id + ", firstName=" + firstName + ", lastName="
+ lastName + ", height=" + height + " in" + ", weight=" + weight
+ " lbs" + ", bmi=" + getBodyMassIndex() + "]";
}
}
}
Execute
When you run the Sort program in a terminal, you should see output like this:
[id=2, firstName=Charles, lastName=Dickens, height=69 in, weight=160 lbs, bmi=23.625288]
[id=1, firstName=Jane, lastName=Austen, height=67 in, weight=130 lbs, bmi=20.358654]
[id=4, firstName=Alex, lastName=Smith, height=65 in, weight=160 lbs, bmi=26.622484]
[id=3, firstName=Jane, lastName=Doe, height=65 in, weight=145 lbs, bmi=24.126627]
The results are in descending order by height. The last two results both have the same height, so they are further ordered by weight.
Next Step
Next Step: Grouping Results ›