How to put List data with different generic type with same Return type?

Question

My problem is that ClassB is a common bean class i have to return(Json data format using @ResponseBody ) simple error message. ClassA is an Entity bean there no setter and getter method to set the error message to the fstList, fstListMap . If there is any alternate solution or else any merging solution for fstListMap,errsecstMap Object to return common Map Object . If any changes only ClassA bean is changeable but ClassB Not changeable.

@RequestMapping(value="getlistOfData",method=RequestMethod.GET)
@ResponseBody
public Map<String, List<ClassA>>
getListOfData(@RequestParam(value="param1")String
                      param1,@RequestParam(value="param2")int param2){

    List<ClassA> fstList=new ArrayList<ClassA>();//ClassA is an hibernate Entity
    Map<String, List<ClassA>> fstListMap=new HashMap<String, List<ClassA>>();

    List<ClassB> errsecstList=new ArrayList<ClassB>();//It is simple Bean class
    Map<String, List<ClassB>> errsecstMap=new HashMap<String, List<ClassB>>();
    ClassB clB=new ClassB();
    boolean isvalid=true;
    try{


        isvalid=newllbean.getisInvalidAge();//This value return drools (set in rule file)
        if(isvalid){//if true then go to this condition
            fstList=serviceClass.getfstList()
            fstListMap.put("fstList", fstList);
            System.out.println("fstList Size: "+fstListMap.size());
            System.out.println("fstList : "+fstListMap);//Am getting this data
        }else{
            String errMessage=clB.setErrorMessage("Age Not valid...");
            errsecstList.add(clB.getErrorMessage());
            errsecstMap.put("errorMessage",errsecstList);
            System.out.println("errMessage Size: "+errsecstMap.size());
            System.out.println("errMessage : "+errsecstMap);//I am getting this value
        }
    }catch(Exception e){
        System.out.println("Exception"+e);
    }
    return fstListMap;
}

how to return errsecstMap?

there is a no parameter to set the errMessage in ClassA entity. I want to return single Map object either if or else condition. There is any solution to return common Map Object to return based on the above code?

Answer 1

Try this (this is not compiled) -

1) Create a Response class like this -

import java.util.List;

public class ResponseClass<T> {

    public String str;
    public List<T> list;

    public String getStr() {
        return str;
    }

    public void setStr(String str) {
        this.str = str;
    }

    public List<T> getList() {
        return list;
    }

    public void setList(List<T> list) {
        this.list = list;
    }

}

2) Modify your existing class like this -

@RequestMapping(value="getlistOfData",method=RequestMethod.GET)
@ResponseBody
public ResponseClass<T>
getListOfData(@RequestParam(value="param1")String
                      param1,@RequestParam(value="param2")int param2){

    List<ClassA> fstList=new ArrayList<ClassA>();//ClassA is an hibernate Entity
    ResponseClass<ClassA> responseA = new ResponseClass<>();

    List<ClassB> errsecstList=new ArrayList<ClassB>();//It is simple Bean class
    ResponseClass<ClassB> responseB = new ResponseClass<>();

    ClassB clB=new ClassB();
    boolean isvalid=true;

    try{


        isvalid=newllbean.getisInvalidAge();//This value return drools (set in rule file)
        if(isvalid){//if true then go to this condition
            fstList=serviceClass.getfstList()
            responseA.setStr("fstList");
            responseA.setList(fstList);
            System.out.println("fstList Size: "+fstListMap.size());
            System.out.println("fstList : "+fstListMap);//Am getting this data
            return responseA;
        }else{
            String errMessage=clB.setErrorMessage("Age Not valid...");
            errsecstList.add(clB.getErrorMessage());
            responseB.setStr("errorMessage");
            responseB.setList(errsecstList);
            System.out.println("errMessage Size: "+errsecstMap.size());
            System.out.println("errMessage : "+errsecstMap);//I am getting this value
            return responseB;
        }
    }catch(Exception e){
        System.out.println("Exception"+e);
    }
}

Obviously, above code can be easily optimized based on your user case. This is a simple implementation.