Skip to main content

Data types in Java and Groovy


All the java people know, Java have two different kind of data types for storing data, those are
   1. Primitive types (such as int,float,char, and boolean)
   2. Reference types (such as String and Object)

The disadvantages of primitive types.
  1. You cannot call methods, an values of primitive types. See the example,
     int a = 10;
     a.toSting();
  If you do like this, while compilation time, the JVM will give the following error.
    "You cannot invoke on toString() on primitivt type int"
  To overcome this issue, the java developers needs Wrapper classes, such as Integer for int, Float for float, and etc.., See the below example
   Integer a= new Integer(10);
   a.toString();

But In Groovy we don't have these kind of headache, because it treats everything as an object.
I am going to add two integer arraylist values using both Groovy and Java, then see the advantage of Groovy.

Java Example: 
public class AddArrayList{
    public static void main(String[] args) {
        ArrayList number1 = new ArrayList();
        number1.add(new Integer(10));
        number1.add(new Integer(20));
        number1.add(new Integer(30));
        ArrayList number2 = new ArrayList();
        number2.add(new Integer(10));
        number2.add(new Integer(20));
        number2.add(new Integer(30));
        ArrayList number3 = new ArrayList();
        for(int i=0;i<3;i++) {
            number3.add(new Integer(number1.get(i)+number2.get(i)));
        }
        System.out.println("Addition Results: " + number3);
    }
}
Groovy Example: 
def number1 = [10,20,30]
def number2 = [10,20,30]
def number3 = []
3.times {
   number3 << number1[it] + number2[it]
}
println "Addition Results: " + number3


Note: The Groovy automatically done boxing and unboxing operation, whenever it's need.

Comments

Popular posts from this blog

Getting key/value pair from JSON object and getting variable name and value from JavaScript object.

Hi, I had faced one issue like this. I have an JSON object but I don't know any key name but I need to get the all the key and corresponding value from JSON object using client side JavaScript. Suddenly I wondered whether it's possible or not, after that I had done lot of workaround and finally got this solution. See the below example.
function getKeyValueFromJSON() {
var jsonObj = {a:10,b:20,c:30,d:50}; for(var key in jsonObj) {       alert("Key: " + key + " value: " + jsonObj[key]);     }  }
 In this example I have created the one json array as string, and converted this string into JSON object using eval() function. Using for-each loop I got all the key value from jsonObj, and finally using that key I got the corresponding value.
 Finally I got the alert like this,

 Key: a value:10
   Key: b value:20
   Key: c value:30
   Key: d value:50

 During this workaround I got one more idea, using this same way I got all the variable name and corresponding value from Java…

Simple Login Application Using Spring MVC and Hibernate – Part 1

I hope developers working in web application development might hear about MVC architecture. Almost all technologies provide support for MVC based web application development, but the success is based on many factors like reusable of the code, maintenance of the code, future adaption of the code, etc..,  The success of the Spring MVC is “Open for extension and closed for modification” principle. Using Spring MVC the developers can easily develop MVC based web application. We don’t need any steep learning curve at the same time we need to know the basics of spring framework and MVC architecture. The Spring MVC consists of following important components. 1. Dispatcher servlet
2. Controller
3. View Resolver
4. Model Spring MVC - Overview  The overall architecture of Spring MVC is shown here.  1. When “Dispatcher Servlet” gets any request from client, it finds the corresponding mapped controller for the request and just dispatches the request to the corresponding controller. The reque…

Simple Login Application Using Spring MVC and Hibernate – Part 2

I hope you have visited my part1 of my tutorial. Let’s see the steps for integrating hibernate framework into Spring MVC. Here I have used MySQL database. I have created one database called “springmvc” and created one table called “user” with userid, username, password fields.
 I have inserted some records into table like this. Step 1: Creating User POJO class.  We need to create a User POJO class for mapping user table. Ok let’s create it. Step 2: Creating hibernate mapping xml file for user class.  In hibernate we need to create hibernate mapping xml file for all domain class for mapping into corresponding database table. Instead of creating xml file you can use annotation for mapping domain class into database table. This is my mapping xml document created for mapping our user domain class into user database table. Step 3: Creating authenticate service class.
 The method “verifyUserNameAndPassword” present in “AuthenticateService” class is used for  verifying the user name and pa…