import org.bson.types.*;

import java.util.*;

public class Test {



    public static void main(final String [] pArgs) throws Exception {

        ObjectId [] objIds = new ObjectId[1000000];
        String [] strs = new String[objIds.length];

        for (int idx=0; idx < objIds.length; idx++) {
            objIds[idx] = ObjectId.get();
            objIds[idx].hashCode();
            strs[idx] = "123456"+idx;
            strs[idx].hashCode();
        }

        for (int idx=0; idx < strs.length; idx++) {
            final ObjectId objId = objIds[idx];
            final String str = strs[idx];
        }

        Set<Object> set = new HashSet<>(objIds.length);

        // Initial
        for (int idx=0; idx < objIds.length; idx++) set.add("test");
        set.clear();

        System.gc();

        Thread.sleep(2000);

        long startTime, execTime;

        // String
        startTime = System.currentTimeMillis();
        for (int idx=0; idx < strs.length; idx++) set.add(strs[idx]);
        execTime = System.currentTimeMillis() - startTime;
        System.out.println("string: " + execTime);
        set.clear();
        System.gc();

        // ObjectId
        startTime = System.currentTimeMillis();
        for (int idx=0; idx < objIds.length; idx++) set.add(objIds[idx]);
        execTime = System.currentTimeMillis() - startTime;
        System.out.println("objectid: " + execTime);
        set.clear();
        System.gc();

        // String
        startTime = System.currentTimeMillis();
        for (int idx=0; idx < strs.length; idx++) set.add(strs[idx]);
        execTime = System.currentTimeMillis() - startTime;
        System.out.println("string: " + execTime);
        set.clear();
        System.gc();

        // ObjectId
        startTime = System.currentTimeMillis();
        for (int idx=0; idx < objIds.length; idx++) set.add(objIds[idx]);
        execTime = System.currentTimeMillis() - startTime;
        System.out.println("objectid: " + execTime);


    }

}