Remote method Invocation (RMI)

Remote method invocation is used to invoke methods across the networks...... The objects have to be registered in the rmi-registry..... Its like the yellow pages where all the entries are registered. From the Rmi- Registry we can access the objects but the service name has to be known to access the objects.


Remote Interface :


import java.rmi.Remote;
import java.rmi.RemoteException;

public interface remote extends Remote {
    int getSum(int a,int b) throws RemoteException;
}

Server :




import java.rmi.*;
import java.rmi.server.*;

public class server extends UnicastRemoteObject
                           implements remote
{
    public server() throws RemoteException {
        super();
    }

    public int getSum(int a,int b) {
return a+b;
    }

    public static void main(String[] args) {
      
        try {
            server engine = new server();
            Naming.rebind("samplermi", engine);
            System.out.println("Server bound");
        } catch (Exception e) {
            System.err.println("server exception: " + e.getMessage());
            e.printStackTrace();
        }
    }
}

Naming.rebind() method puts the engine object in the name "samplermi".

Client :

// Java Document

import java.rmi.*;

public class client {
    public static void main(String args[]) {
try {
            remote obj = (remote) Naming.lookup("samplermi");
            System.out.println(obj.getSum(10,20));
        } catch (Exception e) {
            System.err.println("client exception: " + e.getMessage());
            e.printStackTrace();
        }
    }  
}

The client access the remote object using the "samplermi" service name.

Grab from Internet

If u want to scrap or grab any thing from internet just use this code ..........

Java Scrapping code :

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;




public class Grab {
public static void main(String a[]) throws IOException
{
String url="http://yahoo.com";
URL u=new URL(url);
URLConnection uc=(HttpURLConnection) u.openConnection();
DataInputStream br = new DataInputStream(new BufferedInputStream(uc
.getInputStream()));

int len;
while ((len = br.read()) != -1){
System.out.println((char)len);
}}
}


Just change the "url" variable alone to grab from any other sites.

Simple Short Cuts in Eclipse

Dont spend much time in working with indentation and comments in eclipse.......
Eclipse provides much more easier way to do this.

These are some of the most used short cuts in eclipse which makes your work easier.

Run a Program : ctrl+F11


System.out.println : after typing "syso" press ctrl + space 

Toggle comment : ctrl + /    (//comments)

Block comment : ctrl + shift + / (/* block comment */)

Remove Block Comments : ctrl + shift + \

before this, select the content which you have to comment.

To correct Indentation  : ctrl + I
      
To format the contents : ctrl + shift + f


Organize imports : ctrl+shift+O


Undo Typing : ctrl +z 

To select perspectives : ctrl + F8

Wrod Completion : Alt + / or ctrl+ space

Shit I want my Old versions of codes back in Eclipse

Problem :
I'm a developer in java, I use Eclipse to develop my application. I've encountered a new problem,
My yesterday's code was working fine, but my new code is not working. 
I want my yesterday's code back in eclipse.


Is there any way in eclipse ??


Solution :


Eclipse provides a new way to get your past codes back.


Right Click on the code area -> Local History --> compare with option 


You can find the older versions of the code. You can find older versions with exact time stamp.
Click the code and compare with your code. 

How to add Run time variables in Eclipse

If u r using eclipse as IDE to develop your project and got struck at how to pass run time arguments to a program .... here is the solution to add the run time Arguments in Eclipse.

select Run->Run Configurations ->Arguments tab

1.click the run option

2. select RunConfiguration option

3. Select the Arguments tab 

String.split()

Use of the String.split()
split() is used to split a given string based on a pattern.......

code :


public class UseOfSplit {
public static void main(String args[]) {
String str = "This is the sample String to split";
String pattern=" ";
String[] tmp = str.split(pattern);
for (int i = 0; i < tmp.length; i++) {
System.out.println(tmp[i] + "------");
}
}
}


output :


This------
is------
the------
sample------
String------
to------
split------

java code to Read from File

Java code to read from a file.....

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;


public class ReadFromFile {


public static void main(String[] args) throws IOException {


BufferedReader in = new BufferedReader(new FileReader("sample.txt"));
String str;
in.readLine();


while ((str = in.readLine()) != null) {
System.out.println(str);


}
}


}

Exception involved :
  
       Exception in thread "main" java.io.FileNotFoundException: sample.txt (The system cannot find the file specified)
at java.io.FileInputStream.open(Native Method)
at java.io.FileInputStream.<init>(FileInputStream.java:106)
at java.io.FileInputStream.<init>(FileInputStream.java:66)
at java.io.FileReader.<init>(FileReader.java:41)
at Snap.main(Snap.java:14)

Which means File not found in the path.

How to resolve this error: 

Make sure that this "sample.txt" File resides where the bin folder exists