Java - Is it possible to instance for a UserDefined Class or java primitive types

Question

I have a user defined class like the following,

package com.hexgen.tools;

public class UserDefinedParams {
    private String dataType="";
    private String isArray="";
    public String getDataType() {
        return dataType;
    }
    public void setDataType(String dataType) {
        this.dataType = dataType;
    }
    public String getIsArray() {
        return isArray;
    }
    public void setIsArray(String isArray) {
        this.isArray = isArray;
    }

}

dataType and isArray the values for this if dataType -> this may have userdefined pojo class or java primitive type and if isArray ->this will have Y or N. based on this how to create something like:

if dataType someUserDefinedPOJO and isArray Y

-> someUserDefinedPOJO[] obj = new someUserDefinedPOJO();

vise versa for java primitive types too.

is it possible through reflection in java?

How to do this?

Best Regards

What do you want to achieve by this ? Do you want to add the dynamic variables and the corresponding code to your source code ? — Apurv
– Apurv, Commented Apr 24, 2013 at 9:24
I'd suggest you have a look at reflection in Java. However, if this is an important functionality in your program, you will be much easier off with a weak typed programming language. — MarioDS
– MarioDS, Commented Apr 24, 2013 at 9:24
I'm not sure I'm following, but note that Object can store pretty much anything. Regardless, you'd be much better off redesigning your program such that what you're trying to do is no longer required. — Bernhard Barker
– Bernhard Barker, Commented Apr 24, 2013 at 9:32

Dima · Accepted Answer · 2013-04-24 09:25:15Z

4

just use a HashMap<String,Object> , you can define all your variables in there, for example:

HashMap<String,Object> map=new HashMap<String,Object>();
map.put("myVarName",new Object());

System.out.printlb(map.get("myVarName"));

answered Apr 24, 2013 at 9:25

Dima

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2 Comments

Java Questions Over a year ago

this is when we know what is going to come, if so what is the need for me to create instance dynamically and create it at source level itself

Dima Over a year ago

its the best imitation of dynamic variables, you can put any name that comes from any place, its a string

Community · Accepted Answer · 2017-05-23 11:43:18Z

1

There are no dynamic variables in Java. Java variables have to be declared in the source code.

Depending on what you are trying to achieve, you should use an array, a List or a Map; e.g. See here.

int n[] = new int[3];
for (int i = 0; i < 3; i++) {
    n[i] = 5;
}

List<Integer> n = new ArrayList<Integer>();
for (int i = 1; i < 4; i++) {
    n.add(5);
}

Map<String, Integer> n = new HashMap<String, Integer>();
for (int i = 1; i < 4; i++) {
    n.put("n" + i, 5);
}

edited May 23, 2017 at 11:43

CommunityBot

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answered Apr 24, 2013 at 9:26

Achintya Jha

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Comments

Community · Accepted Answer · 2017-05-23 12:28:08Z

1

I think you should look into java reflection. But this has already posted on SO.

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edited May 23, 2017 at 12:28

CommunityBot

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answered Apr 24, 2013 at 9:26

JDGuide

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MarioDS · Accepted Answer · 2013-04-24 09:28:10Z

1

Another possible route is to go with generics:

public class CustomVariable<E> {
    private E var;

    public CustomVariable<E>(E value){
        var = value;
    }
}

But I wouldn't know about arrays though.

answered Apr 24, 2013 at 9:28

MarioDS

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