Random Number Generation and Formatting in Thymeleaf
All examples presented in this article have been tested on Thymeleaf 3.1 and are applicable to various Thymeleaf scenarios, such as generating random numbers in Halo CMS themes.
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Integers
Generate random integer in range [min, min+range)
${#numbers.formatDecimal(T(java.lang.Math).floor(T(java.lang.Math).random()*range+min),0,0)}
Generate random integer in range [min, max]
${#numbers.formatDecimal(T(java.lang.Math).floor(T(java.lang.Math).random()*(max-min+1)+min),0,0)}
Click to view examples
A <p> tag displaying an integer between [1, 6) ([1, 5]). Possible results: 1, 2, 3, 4, 5.
Method 1
<p
th:with="range=5,min=1"
th:text="${#numbers.formatDecimal(T(java.lang.Math).floor(T(java.lang.Math).random()*range+min),0,0)}"
></p>
Method 2
<p
th:with="max=5,min=1"
th:text="${#numbers.formatDecimal(T(java.lang.Math).floor(T(java.lang.Math).random()*(max-min+1)+min),0,0)}"
></p>
Using as List Index
No need for #numbers.formatDecimal when used as list index. Replace my_list with your actual list variable:
Click to view example
<p
th:with="randomIndex=${T(java.lang.Math).floor(T(java.lang.Math).random()*#lists.size(my_list))}"
th:text="${my_list[randomIndex]}"
></p>
Formatting Control
Formatted random integer in [min, min+range)
Format: Integer part ≥ integerDigits (padded with leading zeros), decimal part fixed to decimalDigits.
${#numbers.formatDecimal(T(java.lang.Math).floor(T(java.lang.Math).random()*range+min),integerDigits,decimalDigits)}
Formatted random integer in [min, max]
Same formatting rules as above:
${#numbers.formatDecimal(T(java.lang.Math).floor(T(java.lang.Math).random()*(max-min+1)+min),integerDigits,decimalDigits)}
Click to view examples
A <p> tag displaying an integer between [0, 5) ([0, 4]). Possible results: 000.00, 001.00, 002.00, etc.
Method 1
<p
th:with="range=5,min=0,integerDigits=3,decimalDigits=2"
th:text="${#numbers.formatDecimal(T(java.lang.Math).floor(T(java.lang.Math).random()*range+min),integerDigits,decimalDigits)}"
></p>
Method 2
<p
th:with="max=4,min=0,integerDigits=3,decimalDigits=2"
th:text="${#numbers.formatDecimal(T(java.lang.Math).floor(T(java.lang.Math).random()*(max-min+1)+min),integerDigits,decimalDigits)}"
></p>
Decimals/Floats
Generate random float in [min, max)
${T(java.lang.Math).random()*(max-min)+min}
Click to view example
A <p> tag displaying a float between [0.5, 1.8). Possible results: 1.46833041859471749, 0.5578399752996518908, etc.
<p
th:with="max=1.8,min=0.5"
th:text="${T(java.lang.Math).random()*(max-min)+min}"
></p>
Formatting Control
Formatted random float in [min, max)
Format: Integer part ≥ integerDigits (padded with leading zeros), decimal part fixed to decimalDigits.
${#numbers.formatDecimal(T(java.lang.Math).random()*(max-min)+min,integerDigits,decimalDigits)}
Click to view example
A <p> tag displaying a float between [0.5, 150.8). Possible results: 00.83, 70.22, 150.23, etc.
<p
th:with="max=150.8,min=0.5,integerDigits=2,decimalDigits=2"
th:text="${#numbers.formatDecimal(T(java.lang.Math).random()*(max-min)+min,integerDigits,decimalDigits)}"
></p>
Project Status
As of publication (February 20, 2025), the Thymeleaf random number feature request remains open with no updates:
Random integer in #numbers · Issue #787 · thymeleaf/thymeleaf
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