Print File size using Java

If you ever want to print the file size using Java, use the following piece of code below :

import java.io.*;

public class FileSize {

public static void main(String[] args) {

File f = new File("//Users//ironcladzone//Downloads//image1.jpg");

System.out.println("File size in bytes = " +f.length());

System.out.println("\nFile size in kb = " +f.length()/1024);

}

}

Output :

File size in bytes = 241833

File size in kb = 236

Note that when we use the length() function, it gives us the file size in bytes. For getting output in kilobytes, divide it by 1024. If you want size in megabytes, again divide it by another 1024. So on and so forth...

Add suffix to strings in a file using Awk

Guys, in my previous post yesterday, we discussed how to add a prefix to strings in a file using Awk. Today lets work on the same example to add a suffix to the strings i.e append the strings with characters in the end.

We'll use the same set of phone numbers for formatting :

2127841212
3458922345
7713398403
6461228847

Let's add some characters to the these numbers in the end. How about something like " Extn : 7142". Here's the Awk code to do it below :

awk '{print $0 " Extn : 7142"}' Phones_unformatted.txt

Output :

2127841212 Extn : 7142

3458922345 Extn : 7142

7713398403 Extn : 7142

6461228847 Extn : 7142

Add a prefix to strings in a file using Awk

Suppose you have a file in Unix / Mac OS X which has phone numbers data. I mean lets say I have a text file named Phones_unformatted.txt which has some phone numbers as follows :

2127841212
3458922345
7713398403
6461228847

Now I want to format the phone numbers to have a prefix maybe like a country code +44- . something like :

+44-2127841212
+44-3458922345
+44-7713398403
+44-6461228847

If you observe I need to only append the phone number with some characters in the beginning. We can achieve the same using awk.

A simple awk code will do the trick as follows :

awk '{print "+44-" $0}' Phones_unformatted.txt

Output :

+44-2127841212

+44-3458922345

+44-7713398403

+44-6461228847

Viola!

Create a new directory using Java

In today's example we'll create a new directory using Java. Check out the following code below :

import java.io.*;

public class Create_Directory {

public static void main(String[] args) {

File dir = new File("//Users//ironcladzone//Downloads//TestDir");

boolean DirectoryCreated = dir.mkdir();

if (DirectoryCreated)

System.out.println("Created a new directory");

else

System.out.println("Directory not created");

}

}

Note that we have used the function mkdir() as expected. It returns the value "true" if the directory is created or "false" if not created. We use the variable 'DirectoryCreated' to store this boolean value, based on which it prints a message.

Try executing this program twice. The first time when you execute the program, a directory gets created and you get the output like :

Created a new directory

The second time when you execute the code, a directory does not get created since it already exists. So you'll get the output like :

Directory not created

Accept User Input in Java

For accepting user input in Java refer the following piece of code below :

import java.io.*;

public class User_Input {

public static void main(String[] args) {

String inp="";

System.out.println("Please enter your name : ");

try {

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

inp=br.readLine();

}

catch(IOException e) {

e.printStackTrace();

}

System.out.println("Welcome " +inp);

}

}

Output:

Please enter your name : 

IronCladWriter

Welcome IronCladWriter

Make sure to import java.io.* so as to use the input/output functions. Notice that we have wrapped an InputStreamReader within a BufferedReader. Guys, do check out detailed documentation on BufferedReader and InputStreamReader for better understanding.

Basic string manipulation in Java with Real Examples : Part 1

Hi guys, how you doing today? I just noticed I haven't written anything about Java in quite some time now. Well let's bring Java back into the spotlight with this light subject on basic string manipulation.

Lets try to cover some simple examples covering different scenarios :

Illustration 1 : Extract a substring from a string

In this example we simply extract a part of the string.

public class String_manip {

public static void main(String[] args) {

 String str = "Hello guys. Welcome to IroncladZone";

 

 String sub_str = str.substring(23, 35);

 

 System.out.println (sub_str);

}

}

Output : IroncladZone

Illustration 2 : Replace a substring from a string

In this example we replace the word "guys" with "goodfellas" within the string.

public class String_manip {

public static void main(String[] args) {

String str = "Hello guys. Welcome to IroncladZone";

String replaced_str = str.replace("guys", "goodfellas");

System.out.println(replaced_str);

}

}

Output : Hello goodfellas. Welcome to IroncladZone

Note that strings are immutable. Their value cannot be changed once its created. However we can create a new string with the replaced word/part.

Illustration 3 : Join / Combine two strings i.e Concatenation

In this we simply join 3 strings together using +

public class String_manip {

public static void main(String[] args) {

String str1 = "Welcome";

String str2 = "to";

String str3 = "IroncladZone";

System.out.println(str1 + str2 + str3);

System.out.println(str1 + " " + str2 + " " + str3);

}

}

Output : 

WelcometoIroncladZone

Welcome to IroncladZone

Illustration 4 : Print the length of the string

public class String_manip {

public static void main(String[] args) {

String str = "Welcome to IroncladZone";

System.out.println(str.length());

}

}

Output :

23

Note the length() function used to show the length of the string.

Illustration 5 : Split a string on a whitespace

public class String_manip {

public static void main(String[] args) {

String str = "Welcome to IroncladZone";

String[] new_str = str.split("\\s+");

System.out.println(new_str[0]);

}

}

Output :

Welcome

Notice the \\s+ regex for the whitespace.

That's it for today fellas. I'll try to include some more advanced scenarios in a 2nd part of this post. There's more to come guys, stay tuned...

How to list all Components of a Stream in IBM RTC

Inorder to list all the components of a stream in IBM RTC from the command line, run the following command.

Usage :

lscm list components -r repository-connection-name -w stream-name

Eg : 

lscm list components -r https://jtsrv.uk.hibm.company:9094/jazz -w htse.mydocs.midata.dev

Notice that for this command we haven't used quotes anywhere in the syntax. Also note for the -w switch for workspace, we need to supply the stream name.

The output would be obviously the list of components as expected, something like :

Workspace: (1001) "htse.mydocs.midata.dev"
     Component: (1091) "htse-mydocs-abc"
     Component: (1092) "htse-mydocs-xyz"
     Component: (1093) "htse-mydocs-pqr"