Java and Python both have collection types (or compound data types). For a general introduction into collection types, you might want to have a look at Wikipedia.

One of the most basic collection types is a list. In Java, you use the interface java.util.List to work with a list. This interface has several implementations like ArrayList and LinkedList, both in package java.util. The interface and implementations are part of the extensive collections framework. The Java Tutorial has a nice introduction into the collections framework.

You can create a list as follows.

List stringList = new ArrayList();
stringList.add("foo");
stringList.add("bar");
stringList.add("baz");

Note: before JDK 7, you had to use new ArrayList(). JDK 7 introduced the diamond operator .

The List interface provides all the functionality you would expect. You can ask for the length (or size), access elements by index, lookup elements, ask for a subset, iterate over the list or change elements by index.

System.out.println(stringList.size());

System.out.println(stringList.get(0));
System.out.println(stringList.get(2));

System.out.println(stringList.indexOf(“bar”));

List subList = stringList.subList(0, 2);

for (String s : subList) {
System.out.println(s);
}
subList.set(1, “baz”);

for (String s : subList) {
System.out.println(s);
}

In Python, lists are built into the language. You create a list using square brackets.

>>> mylist = ['spam', 'eggs', 'bacon']

The available operations are very similar to what you can do with java.util.List. Ask for the length, access elements by index, lookup elements, ask for a subset, iterate over the list or change elements by index.

>>> len(mylist)
3
>>> mylist[0]
'spam'
>>> mylist[2]
'bacon'
>>> mylist.index('eggs')
1
>>> sublist = mylist[0:2]
>>> for s in sublist:
...     print(s)
... 
spam
eggs
>>> sublist[1] = 'bacon'
>>> for s in sublist:
...     print(s)
... 
spam
bacon
>>>

Of course, there’s much more that can be done with lists. I suggest that you have a look at the Python documentation on data structures.

Coding conventions are an important part of software development.

Contrary to popular belief, it is not only the functionality of the code that matters, what the code does, but also the readability, what the code looks like. That is because code is read much more often than it is written. If, within a team or organization, everybody formats his code differently or uses different naming conventions, that is a recipe for disaster.

People have debated for ages about using tabs versus spaces and how many of them, but what is more important is consistency. When existing code uses tabs, keep it this way. When you start from scratch, you have a choice.

Code Conventions for the Java Programming Language can be found at Oracle Technology Network. Python has a Python Enhancement Proposal (PEP) for this: PEP 8 — Style Guide for Python Code.

Developers should be familiar with these best practises and try to follow the rules. There are tools to help you with this. For example, Pylint for Python and Checkstyle for Java. However, as PEP 8 points out, it is equally important to know when not to follow the rules. To be consistent with existing code, for example.

A good starting point is the Wikipedia article about coding conventions.