Extract value from string using regex in java

So suppose you want to extract values from a string based on a certain regex pattern. The thing that i didn't know was that I needed to use () around the data I wanted to capture.


Output

http://home.com
56

I dedicate this post to all laymen out there, who get confused with coding and stuff

Listen for text changes on EditText

Assume you want to enable a button only if some changes have been made to a form. You can do this by using android.text.TextWatcher
Simply create a new instance of TextWatcher and implement the required methods
There you have it. For more info checkout http://developer.android.com/reference/android/text/TextWatcher.html

The magic of grep and sed and xargs

You want to get all files that have a certain string

grep -rl "ToMatch" <folder>

You then want to replace that string with another string

grep -rl "ToMatch" | xargs sed -i s/ToMatch/Replaced/g

The xargs command passes the values from "grep -rl "ToMatch" <folder>" to the sed command as arguments

For more info on how to use xargs look at http://unixhelp.ed.ac.uk/CGI/man-cgi?xargs

Delete values from a map through a loop

So you woke up today and you want to delete values from a map, as you loop through the map (For whatever reason). So you right this is groovy

Code
Output

[a,b,c]

Wrong !!!!
You actually get a ConcurrentModificationException.... hahaha :D <- This is me laughing at you. So you need to

Java String.equals versus == [duplicate]

String.equals("some string") checks the contents of the string
"==" checks if the object references are identical

View Logs of CRON jobs

grep CRON /var/log/syslog

Grails getting the current environment name

Suppose you have created your own custom environment ,for example, purposes of deployment.
You may at times need to get the value of the environment. To do so

import grails.util.Environment

println Environment.current.name