StrongParameters in Java to filter parameters from view

StrongParameters.java

package com.company;


import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;

public class StrongParameters {

    public static void main(String[] args){

        GenericModel model =  new GenericModel();

        Map<String,Object> requestParams =  new HashMap<String,Object>(){
            {
            put("name",new ArrayList<String>(Arrays.asList("teste")));
            put("categoryId",new ArrayList<String>(Arrays.asList("1111")));
            put("injection",new ArrayList<String>(Arrays.asList("xxx")));

            }
        };
;


        StrongParameters sp1 = new StrongParameters(requestParams)
                .require(new String[]{"name","categoryId"})
                .reject(new String[]{"injection"});

        System.out.println( model.assignAttributes(sp1));
        System.out.println( model);

        model =  new GenericModel();
        StrongParameters sp2 = new StrongParameters(requestParams)
                .require(new String[]{"non-exist"})
                .reject(new String[]{"injection"});


        System.out.println( model.assignAttributes(sp2));
        System.out.println( model);



    }

    private HashMap<String,Object> rawParametes;
    private HashMap<String,Object> params;

    Boolean valid = true;

    public Boolean isValid(){
        return valid;
    }
    public HashMap<String,Object> project() throws Exception{
        if(isValid()){
            return params;
        }else{
            throw new Exception();
        }
    }

    public StrongParameters(Map<String,Object>  rawParametes) {
        this.rawParametes =  (HashMap)rawParametes;
        this.params =  new HashMap<String,Object>();
        filterParams();
    }

    private void filterParams(){
        for(Entry<String, Object> entry : rawParametes.entrySet()) {
            String key = entry.getKey();
            ArrayList value = (ArrayList)entry.getValue();
            if(value.size() == 1){
                params.put(key, value.get(0));
            }else{
                params.put(key, value);
            }

        }
    }

    public StrongParameters require(String[] paramsNames){
        for(String paramName : Arrays.asList(paramsNames)){
            if(params.get(paramName) == null){
                valid = false;
            }
        }
        return this;
    }

    public StrongParameters reject(String[] paramsNames){
        for(String paramName : Arrays.asList(paramsNames)){
            params.remove(paramName);
        }
        return this;
    }

}

class GenericModel{

    String name;
    Integer categoryId;
    String injected;

    public String toString(){
       return  "name:"+name + ", categoryId:" + categoryId + ", injected:" + injected;
    }

    //isso aqui pode armazenar aos valores em variáveis temporárias para caso ocorra um erro
    // não
    public Boolean assignAttributes(StrongParameters parameters){
        HashMap<String,Object> params;
        String _name;
        Integer _categoryId;
        String _injected;

        try {
            params = parameters.project();

            if(params.get("name") != null){
                _name = (String) params.get("name");
            }
            if(params.get("categoryId") != null){

                _categoryId = Integer.valueOf((String)params.get("categoryId"));
            }
            if(params.get("injected") != null){
                _injected = (String) params.get("injected");
            }
            name = _name;
            categoryId = _categoryId;
            injected = _injected;
            return true;
        } catch (Exception e) {
            return false;
        }
    }
}