Variable named “var” causing compilation error

Question

while using JFrame, I tried setting the icon image with the following code

ImageIcon image = new ImageIcon("C:\\barney.jpg");
frame.setIconImage(image.getImage());

It works as expected, but when I set the "C:\\barney.jpg" as aString variable

String var = "C:\\barney.jpg";
ImageIcon image = new ImageIcon(var);
frame.setIconImage(image.getImage());

The compiler displays Exception in thread "main" java.lang.Error: Unresolved compilation problem

Another point of confusion is why the line in the error code refer to the public static void main(String[] args) line instead of String var = "C:\\barney.jpg"; which actually causes the error?

Depending on the java version `var` is a really bad variable name. Actually regardless of the java version it is a bad name since the variable name should hint at the meaning / usage of it. — luk2302, Oct 08 '21 at 15:09
Did you try not naming it var? Isn't var a keyword in Java nowadays? — Thomas Stachl, Oct 08 '21 at 15:09
@ Thomas Stachl, i just changed the variable to `x` and i still experience the same thing — Ser.T, Oct 08 '21 at 15:21
The error message will contain more than that _Unresolved compilation problem_. Include that in your question. Also, don't try to run code that doesn't compile. — Sotirios Delimanolis, Oct 08 '21 at 15:39
@sotirios I swear, that's the only error I'm getting. I use VS code, could that be why? — Ser.T, Oct 08 '21 at 16:13
Try to compile with `javac` directly. Please provide a [mcve]. — Sotirios Delimanolis, Oct 08 '21 at 16:15

0xff · Answer 1 · 2021-10-08T15:18:53.950

2

var is a reserved keyword in java. You can't name any variable var. Try some other name.

The reason behind this is that var is used for assigning variables so to not confuse the compiler you cannot use it as a variable name.

Note that it does compile in java 8 and prior as the var keyword has not had been implemented back then. Additionally starting from java 17 it is possible again to use it as a variable name.

var, with some limitations lets you replace standart assignments in java.

String someString1 = "Hello, World!";
// gets turned into
var someString2 = "Hello, World!";

This also works with other assignments

edited Oct 08 '21 at 15:18

answered Oct 08 '21 at 15:09

0xff

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Ah Interesting. Didn't know it was possible in java 17! – 0xff Oct 08 '21 at 15:13
@jadefalke changing the variable name still causes the same exception, i used `x` instead of `var` – Ser.T Oct 08 '21 at 15:19
@user16320675 `Exception in thread "main" java.lang.Error: Unresolved compilation problem: at a1.main(a1.java:5)` that's all i'm getting – Ser.T Oct 08 '21 at 15:23
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@ser.T please don't edit a question in such a way that the original question is not inferable anymore – 0xff Oct 08 '21 at 15:23
That is not correct. **var** is __not__ a reserved keyword, rather it is a reserved type name in Java, and so you can use variable with **var** name. See here: https://stackoverflow.com/questions/49102553/what-is-the-conceptual-difference-between-a-restricted-keyword-and-reserved-t#:~:text=A%20%22reserved%20type%20name%22%20is,using%20an%20additional%20lookup%20step. – Mikhail2048 Mar 10 '23 at 08:29
P.S: See the JLS section about keywords: https://docs.oracle.com/javase/specs/jls/se7/html/jls-3.html#jls-3.9 – Mikhail2048 Mar 10 '23 at 08:57

Variable named “var” causing compilation error

1 Answers1