{"id":112812,"date":"2022-02-10T07:00:00","date_gmt":"2022-02-10T05:00:00","guid":{"rendered":"https:\/\/www.javacodegeeks.com\/?p=112812"},"modified":"2022-02-08T14:34:37","modified_gmt":"2022-02-08T12:34:37","slug":"calculations-in-quarkus-qute-using-atomicinteger","status":"publish","type":"post","link":"https:\/\/www.javacodegeeks.com\/2022\/02\/calculations-in-quarkus-qute-using-atomicinteger.html","title":{"rendered":"Calculations in Quarkus Qute using AtomicInteger"},"content":{"rendered":"

Quarkus’ Qute Templating Engine is very handy for creating server-side rendered pages. Besides the regular loops and control structures, there\u2019s also a possibility to set and update variables, at least with a small trick. In the following, we\u2019ll see how to do some arithmetic calculations using Java\u2019s AtomicInteger<\/code>.<\/p>\n

Usually, you can invoke methods of objects that are passed to Qute, but you can\u2019t easily update the variables itself. There\u2019s the {#let}<\/code> directive to define variables but in order to update values we need to use types that provide methods to do so, unlike Java primitives.<\/p>\n

Imagine we\u2019d like to have multiple nested loops and would like some global counter:<\/p>\n

{#let counter=math:atomicInt(1)}\n{#for entry in entries}\n    <li>{counter.getAndIncrement()}. {entry_count}.\n        {entry.title} {#if entry_hasNext}OR{\/}<\/li>\n{\/for}\n\n{#for i in 5}\n    <li>{counter.getAndIncrement()}. {i_count}.\n        Entry number {i}{#if i_hasNext},{\/}<\/li>\n{\/for}\n{\/let}<\/pre>\n
What happens is that the counter<\/code> variable is of type AtomicInteger<\/code> and the getAndIncrement<\/code> method returns and changes the internal numeric value. We provide the instance via a template extension method:
 
<\/div> <\/div><\/p>\n
@TemplateExtension(namespace = \"math\")\nstatic AtomicInteger atomicInt(int initial) {\n    return new AtomicInteger(initial);\n}<\/pre>\n
The result looks like follows:<\/p>\n