Chandru Chandru - 8 months ago 66
Java Question

How to sort ArrayList<Object> in Ascending order android

I have a requirement to sort

ArrayList<Object>
(Custom objects) in Ascending order based upon name. For that purpose I am using comparator method as like

My ArrayList :

ArrayList<Model> modelList = new ArrayList<Model>();


Code I am using:

Comparator<Model> comparator = new Comparator<Model>() {
@Override
public int compare(CarsModel lhs, CarsModel rhs) {

String left = lhs.getName();
String right = rhs.getName();

return left.compareTo(right);

}
};

ArrayList<Model> sortedModel = Collections.sort(modelList,comparator);

//While I try to fetch the sorted ArrayList, I am getting error message


I am completely stuck up and really dont know how to proceed further in order to get sorted list of
ArrayList<Object>
. Please help me with this. Any help and solutions would be helpful for me. I am posting my exact scenario for your reference. Thanks in advance.

Example:

ArrayList<Model> modelList = new ArrayList<Model>();
modelList.add(new Model("chandru"));
modelList.add(new Model("mani"));
modelList.add(new Model("vivek"));
modelList.add(new Model("david"));


Normal List:

for(Model mod : modelList){
Log.i("names", mod.getName());
}


Output :

chandru
mani
vivek
david


My requirement after sorting to be like:

for(Model mod : modelList){
Log.i("names", mod.getName());
}


Output :

chandru
david
mani
vivek

Answer Source

Your approach was right. Make your Comparator inner like in the following example (or you can create a new class instead):

ArrayList<Model> modelList = new ArrayList<>();
modelList.add(new Model("chandru"));
modelList.add(new Model("mani"));
modelList.add(new Model("vivek"));
modelList.add(new Model("david"));

Collections.sort(modelList, new Comparator<Model>() {
    @Override
    public int compare(Model lhs, Model rhs) {
        return lhs.getName().compareTo(rhs.getName());
    }
});

output:

chandru
david
mani
vivek
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