Actually dateCreated is an Object from the Class Date which is in package java.util and is inside the Object you are defining which is SimpleGeoMetricObject
In other words Java guys wrote this:
package java.util;
public Class Date{
//with its own attributes
public Date(){
...
//and its own constructor
}
...//and it's own methods
}
And provided it to developpers so we can use it in our own Class/Objects and by the way if you import the package like this import java.util.Date;
in the beginning of your file you would only need to construct Date like follows : Date objectDate = new Date();