Igor's Blog

This is an instalment of my Code Odium series of articles talking about bad programming practices with focus on Java. In this article I will talk about why splitting up variable declaration and assignment is unnecessary.

I happen across a surprising amount of code that can be improved and recently I've been noticing in quite a few places where variable declaration and assignment has been split up. This ends up with code that looks something like this...
private String myMethod() {
String myString;
myString = "myString";

That got a raised eyebrow response from me so I did some investigation and it turned out that quite a number of IDEs actually flag single line declaration and assignment and offer to 'fix' it...

So why is splitting up declaration and assignment like this unnecessary? It really comes down to the number lines you end up writing and the complexity cues you leave. For a simple assignment like above, splitting up declaration and assignment makes code harder to follow - you have to read two lines instead of one to understand the meaning. It also implies that a more complex or conditional assignment should be in place and maybe there's something missing since it's just a simple assignment instead.

So I would always write something like this...
private String myMethod() {
String myString = "myString";

One line declaration and assignment. There is no way to misinterpret the intention there.

I did mention complex or conditional assignments earlier. In this situation it is ok and in fact mandatory to split up declaration and assignment. These cases are the only places where splitting like that should be done though. For example...
private String myMethod(boolean codingIsCool) {
String myString;
if (codingIsCool) {
myString = "Coding is cool";
else {
myString = "Get outta here!";

So there you go, the basic rule of thumb is do not split up variable declaration and assignment unless there is some complex/conditional logic that governs the value assigned to that variable.


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About — I'm an enthusiastic software engineer and consultant interested in many fields including J2EE, programming, electronics, 3D printing, video games, wood working and gardening.
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