Designing your own iterable stuff

Or, simply, implementing iterator logic in your own class, on which you can iterate or even use for-each loop. Because, for-each works only on Iterator based collections.
Following is a generic Java 7 code that takes into account a simple custom linked list implementation that is generic and can be iterated over, using following steps.

1. The stuff we want to iterate upon has to be Iterable and expose
iterator(). 

2. Design a java.util.Iterator by overriding hasNext(), next() and remove().

Sorting Key-Value pairs in Java

Saw making your own sorting logic by implementing Comparable or Comparator? If not, click here. Now, how about sorting key-value pairs! Well, we need just a little code modification. See following code sample that sorts key-value pairs, first by key, then values. Look at the compareTo method implementation.

Comparable and Comparator- When and how to use? [Concise]

When there comes the need of sorting objects, be it using Collections.sort() or just adding elements to Treeset etc, java.lang.Comparable and java.util.Comparator come into picture. For default sorting of objects in the collection, we need to implement Comparable and override below method in that class, unless we are using some pre-defined class that already implements Comparable like String, Integer etc.,

int compareTo(T o)

If we want to provide an external sorting logic to override the default one, the class needs to implement Comparator interface and override the following method:

int compare(T o1, T o2)

The question: Why use Comparator when we already have Comparable?
Answer: If you have authored that class, then you can give a default sorting behavior by implementing Comparable and use that logic to sort whenever needed. Now, let's say that you are using an existing class whose source you can not modify and the default sorting logic of which you are not satisfied with. What now? Just write a Comparator using your own sorting process and use that instance to sort. See below sample programs.

The API information is here:

1. java.lang.Comparable
2. Java.util.Comparator

Lets dig into this with our custom class.

native2ascii - Native-to-ASCII Converter in Java

This utility converts a file with characters in any supported character encoding to one with ASCII and/or Unicode escapes, or visa versa.

You already have this tool if you have JDK. It is present in your JDK installation bin folder. Its recommended to add JAVA_HOME to your PATH environment variable for access of java tools throughout your machine.

Falling in love with InteliJ Idea Community IDE

The local file history that keeps a track on my changes to a file, I am all smiles now! :~)

Local History - Click on the image to enlarge