Design Patterns & Java Collections

package factorypattern;

public abstract class Builder {

    public abstract void build();
}

package factorypattern;

public class HomeBuilder extends Builder {

    HomeBuilder() {
        System.out.println("HomeBuilder");
    }
    public void build() {
        System.out.println("home builder builts home");
    }
}

package factorypattern;

public class FactoryBuilder extends Builder {

    FactoryBuilder() {
        System.out.println("factory builder");
    }
    public void build() {
        System.out.println("Factory builder builts factory");  
    }

}

package factorypattern;

public class ApartmentBuilder extends Builder {

    ApartmentBuilder() {
        System.out.println("Constructor ApartmentBuilder");
    }
    public void build() {
        System.out.println("Apartment builder builts apartment");
    }
}

package factorypattern;

public class BuilderFactory {

    public static Builder createBuilder(String builder) {
    
        if(builder.equals("HomeBuilder")) {
            return new HomeBuilder();
        } else if(builder.equals("FactoryBuilder")){
            return new FactoryBuilder();
        } else {
            return new ApartmentBuilder();
        }
    }
}

package factorypattern;

public class BuilderClient{

    public static void main(String[] args) {
        Builder builder = BuilderFactory.createBuilder("HomeBuilder");
    }
}

To Eliminate duplicates and non duplicate items from the List.

Scenario:

For eg., if the list contains s1,s2,s3,s1,s2,s3,s4 then
the result will be like s1,s2,s3. This how the following code will work.

List list = new ArrayList();
		list.add("S1");
		list.add("S3");
		list.add("S4");
		list.add("S3");
		list.add("S1");
		
ArrayList tempList = new ArrayList();
Set set1 = new HashSet(list);

for (String setString : set1) {
if (Collections.frequency(list,setString) > 1) {
tempList.add(setString);
}