Combine two ArrayList of object and conditionally change value of object while combining

Question

I want to combine two arraylist of similar type. But conditionally, if property of one object match, property of other object than combine them in one.

Here is my model class

public class SampleModel {

    int number;
    String name;
    boolean isSimilar;

    public SampleModel(int number, String name, boolean isSimilar) {
        this.number = number;
        this.name = name;
        this.isSimilar = isSimilar;
    }

    public int getNumber() {
        return number;
    }

    public void setNumber(int number) {
        this.number = number;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public boolean isSimilar() {
        return isSimilar;
    }

    public void setSimilar(boolean similar) {
        isSimilar = similar;
    }


    @Override
    public boolean equals(Object o) {
        boolean result = false;
        if (this == o){
            result = true;
        }
        if (o == null || getClass() != o.getClass()){
            result = false;
        }
        SampleModel that = (SampleModel) o;

        if(name.matches("(.*)"+that.name+"(.*)")){
            result = true;
        }

        if(name.matches("(.*)"+that.name)){
            result = true;
        }

        if(name.matches(that.name+"(.*)")){
            result = true;
        }

        if(name.contains(that.name)){
            result= true;
        }

        return result;
    }

    @Override
    public int hashCode() {
        return Objects.hash(name);
    }
}

And I have two arrylist of this type of object Like this

    ArrayList<SampleModel> sampleModels_one = new ArrayList<SampleModel>();
    ArrayList<SampleModel> sampleModels_two = new ArrayList<SampleModel>();
    ArrayList<SampleModel> combined = new ArrayList<SampleModel>();

    sampleModels_one.add(new SampleModel(1,"a",true));
    sampleModels_one.add(new SampleModel(1,"b",true));
    sampleModels_one.add(new SampleModel(1,"c",true));

    sampleModels_two.add(new SampleModel(1,"b",false));
    sampleModels_two.add(new SampleModel(2,"c",false));
    sampleModels_two.add(new SampleModel(3,"d",false));
    sampleModels_two.add(new SampleModel(3,"e",false));

I want to combine them in such way, so the output of combined will be like this

SampleModel(1,"a",true)
SampleModel(1,"b",true)
SampleModel(1,"c",true)
SampleModel(1,"d",false)
SampleModel(1,"e",false)

I have looked other SO question but couldn't find a efficient way to do this.

Answer 1

You can do it with Set like this.(can use linkedhashset for maintaining order)

        combined.addAll(sampleModels_two);
        combined.addAll(sampleModels_one);

        Set<SampleModel> hs = new LinkedHashSet<>();
        hs.addAll(sampleModels_one);
        hs.addAll(sampleModels_two);
        combined.clear();
        combined.addAll(hs);

Answer 2

If you don't care about the ordering of the elements, it might make more sense to use a Set instead. If you add elements to a Set then the elements are tested with .equals and duplicates are not added.

However if you need to have some sense of ordering to your list then you can use the removeAll(Collection<?> c) method to remove duplicate elements of the list.

Like this ...

ArrayList<SampleModel> combined = new ArrayList<SampleModel>(); combined.addAll(sampleModels_one); combined.removeAll(sampleModels_two); combined.addAll(sampleModels_two);