DisplayTool installation and usage - maven

Question

I am using Velocity 1.7 to format string and I had some trouble with default values. Velocity by itself has no special syntax for case when value is not set and we want to use some another, default value.
By the means of Velocity it looks like:
#if(!${name})Default John#else${name}#end
which is unconveniant for my case.
After googling I've found DisplayTool, according to documentation it will look like:
$display.alt($name,"Default John")
So I added maven dependency but not sure how to add DisplayTool to my method and it is hard to found instructions for this.
Maybe somebody can help with advice or give useful links?..
My method:
public String testVelocity(String url) throws Exception{
Velocity.init();
VelocityContext context = getVelocityContext();//gets simple VelocityContext object
Writer out = new StringWriter();
Velocity.evaluate(context, out, "testing", url);
logger.info("got first results "+out);
return out.toString();
}
When I send
String url = "http://www.test.com?withDefault=$display.alt(\"not null\",\"exampleDefaults\")&truncate=$display.truncate(\"This is a long string.\", 10)";
String result = testVelocity(url);
I get "http://www.test.com?withDefault=$display.alt(\"not null\",\"exampleDefaults\")&truncate=$display.truncate(\"This is a long string.\", 10)" without changes, but should get
"http://www.test.com?withDefault=not null&truncate=This is...
Please tell me what I am missing. Thanks.

Answer 1

The construction of the URL occurs in your Java code, before you invoke Velocity, so Velocity isn't going to evaluate $display.alt(\"not null\",\"exampleDefaults\"). That syntax will be valid only in a Velocity template (which typically have .vm extensions).
In the Java code, there's no need to use the $ notation, you can just call the DisplayTool methods directly. I've not worked with DisplayTool before, but it's probably something like this:
DisplayTool display = new DisplayTool();
String withDefault = display.alt("not null","exampleDefaults");
String truncate = display.truncate("This is a long string.", 10);
String url = "http://www.test.com?"
+ withDefault=" + withDefault
+ "&truncate=" + truncate;
It might be better, though, to call your DisplayTool methods directly from the Velocity template. That's what is shown in the example usage.