linkedlist

Java: A Java list `tail` function (for ArrayList, LinkedList, etc.)

As a brief note today, I was working on a Java/Android application recently, and I needed a “tail” function when I was working on a Java list. What I mean by that is that Scala has a tail function that returns all elements of the list except for the head element, like this:

scala> val x = List(1,2,3,4)
x: List[Int] = List(1, 2, 3, 4)

scala> x.tail
res1: List[Int] = List(2, 3, 4)  //head element removed

and I wanted the same thing in Java.

How to create Scala classes that use generic types (cookbook examples)

This is an excerpt from the Scala Cookbook (partially modified for the internet). This is Recipe 19.1, “How to create Scala classes that use generic types (cookbook examples).”

Problem

You want to create a Scala class (and associated methods) that uses a generic type.

Java 5 for loop syntax example (Java 5 Generics)

Java FAQ: Can you show me an example of the Java 5 for loop syntax? (Java 5 and newer)

Answer: Sure. I've created a sample Java program to demonstrate the Java 5 for-each loop syntax, using both a List with pre-Java5 syntax, and a second example using Java 5 generics syntax.

Java 5 for loop syntax example

Without any further ado, here is the example code:

Java best practice - return a List, not a LinkedList

As I started to mention in another blog post, your Java code will be more flexible when you learn to return more-general object references. In most cases other developers only need to see your interface, not your implementation. Put another way, does it matter to anyone else if you used a LinkedList or an ArrayList? If it doesn't matter, then return a List, or perhaps even a Collection.

A Java LinkedList example

I find that I learn a lot — especially initially — when I can see source code examples. To that end, here’s some sample code showing how to use a Java LinkedList. This uses Java syntax prior to Java 5: