driver-legacy/src/examples/tour/Decimal128LegacyAPIQuickTour.java
public static void main(final String[] args) {
        MongoClient mongoClient;

        if (args.length == 0) {
            // connect to the local database server
            mongoClient = new MongoClient();
        } else {
            mongoClient = new MongoClient(new MongoClientURI(args[0]));
        }

        // get handle to "mydb" database
        DB database = mongoClient.getDB("mydb");


        // get a handle to the "test" collection
        DBCollection collection = database.getCollection("test");

        // drop all the data in it
        collection.drop();

        // make a document and insert it
        BasicDBObject doc = new BasicDBObject("name", "MongoDB")
                                    .append("amount1", Decimal128.parse(".10"))
                                    .append("amount2", new Decimal128(42L))
                                    .append("amount3", new Decimal128(new BigDecimal(".200")));

        collection.insert(doc);


        DBObject first = collection.findOne(QueryBuilder.start("amount1").is(new Decimal128(new BigDecimal(".10"))).get());

        Decimal128 amount3 = (Decimal128) first.get("amount3");
        BigDecimal amount2AsBigDecimal = amount3.bigDecimalValue();

        System.out.println(amount3.toString());
        System.out.println(amount2AsBigDecimal.toString());

    }
public static void main(final String[] args) {
        MongoClient mongoClient;

        if (args.length == 0) {
            // connect to the local database server
            mongoClient = new MongoClient();
        } else {
            mongoClient = new MongoClient(new MongoClientURI(args[0]));
        }

        // get handle to "mydb" database
        DB database = mongoClient.getDB("mydb");


        // get a handle to the "test" collection
        DBCollection collection = database.getCollection("test");

        // drop all the data in it
        collection.drop();

        // make a document and insert it
        BasicDBObject doc = new BasicDBObject("name", "MongoDB")
                                    .append("amount1", Decimal128.parse(".10"))
                                    .append("amount2", new Decimal128(42L))
                                    .append("amount3", new Decimal128(new BigDecimal(".200")));

        collection.insert(doc);


        DBObject first = collection.findOne(QueryBuilder.start("amount1").is(new Decimal128(new BigDecimal(".10"))).get());

        Decimal128 amount3 = (Decimal128) first.get("amount3");
        BigDecimal amount2AsBigDecimal = amount3.bigDecimalValue();

        System.out.println(amount3.toString());
        System.out.println(amount2AsBigDecimal.toString());

    }
Run this main method to see the output of this quick example.

@param args takes an optional single argument for the connection string