public class DataModel {

    String namefile;
    String content;
    String coeff;

    public DataModel( String coeff, String namefile, String content) {
        this.namefile=namefile;
        this.content=content;
        this.coeff=coeff;

    }

    public String getNameFile() {
        return namefile;
    }

    public String getContent() {
        return content;
    }

     public String getCoeff() {
        return coeff;
    }

}

ArrayList<DataModel> dataModels;
        dataModels= new ArrayList<>();

   Collections.sort(dataModels, new Comparator<DataModel>() {
                @Override
                public int compare(DataModel filename, DataModel coeff) {
                    return coeff.getCoeff().compareTo(coeff.getCoeff());
                }
            });