とみせかけてぜんぜん仮想機械じゃないデータ型管理まで書いたところ

RecrioVirtualMachine.java

import java.io.*;
import java.lang.*;
import java.util.*;
import java.util.concurrent.atomic.*;

enum DataType {
    // primitive
    BOOLEAN(true),
    CHARACTER(true),
    INTEGER(true),
    DECIMAL(true),
    STRING(true),
    // non-primitive
    HASH(false),
    LIST(false);
    private boolean isPrimitive;
    DataType(boolean isPrimitive) {
        this.isPrimitive = isPrimitive;
    }
    public boolean isPrimitive() {
        return isPrimitive;
    }
};

class RecrioObject {
    DataType type;
    public String typeToString() {
        return this.type.toString();
    }
    public DataType ofType() {
        return this.type;
    }
    boolean isPrimitive() {
        return this.type.isPrimitive();
    }
}

class PrimitiveObject extends RecrioObject {
    public boolean boolData;
    public char charData;
    public int intData;
    public double decimalData;
    public String strData;
    public PrimitiveObject(DataType type) {
        assert type.isPrimitive();
        this.type = type;
    }
}
class HashObject extends RecrioObject {
    HashMap<String, Integer> hashData;
    public HashObject() {
        this.type = DataType.HASH;
        this.hashData = new HashMap<String, Integer>();
    }
    public void put(String key, int val) {
        this.hashData.put(key, val);
    }
    public int get(String key) {
        return hashData.get(key);
    }
    public void remove(String key) {
        this.hashData.remove(key);
    }
}
class ListObject extends RecrioObject {
    LinkedList<Integer> listData;
    public ListObject() {
        this.type = DataType.LIST;
        this.listData = new LinkedList<Integer>();
    }
    public int getFirst() {
        return this.listData.getFirst();
    }
    public int getLast() {
        return this.listData.getLast();
    }
    public int removeFirst() {
        return this.listData.removeFirst();
    }
    public int removeLast() {
        return this.listData.removeLast();
    }
    public void addFirst(int idxDataUnit) {
        this.listData.addFirst(idxDataUnit);
    }
    public void addLast(int idxDataUnit) {
        this.listData.addLast(idxDataUnit);
    }
}

class DataTable {
    static AtomicInteger storeCount;// for id allocation;
    static HashMap<Integer, RecrioObject> dataStore; // all objects;
    public DataTable() {
        storeCount = new AtomicInteger(0);
        dataStore = new HashMap<Integer, RecrioObject>();
    }
    public static int newRecrioObject(DataType type) {
        int id = storeCount.getAndIncrement();
        RecrioObject obj;
        switch(type) {
        case HASH:
            obj = new HashObject();
            break;
        case LIST:
            obj = new ListObject();
            break;
        default:
            obj = new PrimitiveObject(type);
        }
        System.err.println("new object[" + obj.typeToString() + "] at " + id);
        dataStore.put(id, obj);
        return id;
    }
    public static RecrioObject get(int id) {
        return dataStore.get(id);
    }
    public static void remove(int id) {
        System.err.println("deleted object[" + DataTable.get(id).typeToString() +"] at " + id);
        dataStore.remove(id);
    }
}

class RecrioVirtualMachine {
    public static void main(String args[]) {
        new DataTable();
        // primitive object
        int primitives[] = {
            DataTable.newRecrioObject(DataType.BOOLEAN),
            DataTable.newRecrioObject(DataType.CHARACTER),
            DataTable.newRecrioObject(DataType.INTEGER),
            DataTable.newRecrioObject(DataType.DECIMAL),
            DataTable.newRecrioObject(DataType.STRING)
        };
        // hash object
        int hash = DataTable.newRecrioObject(DataType.HASH);
        HashObject hashObj = (HashObject)DataTable.get(hash);
        hashObj.put("boolean", primitives[0]);
        hashObj.put("character", primitives[1]);
        hashObj.put("integer", primitives[2]);
        // list object
        int list = DataTable.newRecrioObject(DataType.LIST);
        ListObject listObj = (ListObject)DataTable.get(list);
        listObj.addFirst(primitives[0]);
        listObj.addFirst(primitives[1]);
        listObj.addFirst(primitives[3]);
        listObj.addFirst(primitives[4]);
        DataTable.remove(hash);
        DataTable.remove(list);        
        for(int i: primitives) {
            DataTable.remove(i);
        }
    }
}