FreeMarker: Access list/sequence data using index notation

You can access elements of list/sequence using index notation.

 

Example

<#assign primes=[2, 3, 5, 7, 11] >

 

primes[0] return the value at index 0 which is 2

primes[1] return the value at index 1 which is 3

 

Find the below working application.

 

Step 1: Define listIndexNotation.ftl file under src/main/resources/templates folder.

 

listIndexNotation.ftl

<#assign primes=[2, 3, 5, 7, 11] >

Value at 0th index ${primes[0]}
Value at 1st index ${primes[1]}
Value at 2nd index ${primes[2]}
Value at 3rd index ${primes[3]}
Value at 4th index ${primes[4]}

Step 2: Define ‘FreeMarkerUtil’ class that takes a model object and template file as input and merge them.

 

FreeMarkerUtil.java

package com.sample.app.util;

import java.io.StringWriter;
import java.util.Locale;

import freemarker.template.Configuration;
import freemarker.template.Template;
import freemarker.template.TemplateExceptionHandler;

public class FreeMarkerUtil {

	private static final Configuration FREE_MARKER_CONFIGURATION = new Configuration(Configuration.VERSION_2_3_30);

	static {
		FREE_MARKER_CONFIGURATION.setClassForTemplateLoading(FreeMarkerUtil.class, "/templates/");
		FREE_MARKER_CONFIGURATION.setDefaultEncoding("UTF-8");
		FREE_MARKER_CONFIGURATION.setLocale(Locale.US);
		FREE_MARKER_CONFIGURATION.setTemplateExceptionHandler(TemplateExceptionHandler.RETHROW_HANDLER);
		FREE_MARKER_CONFIGURATION.setFallbackOnNullLoopVariable(false);
	}

	public static StringWriter mergeModelAndTemplate(Object modelObject, String ftlFile) throws Exception {
		StringWriter stringWriter = new StringWriter();

		Template template = FREE_MARKER_CONFIGURATION.getTemplate(ftlFile);

		template.process(modelObject, stringWriter);

		return stringWriter;
	}

}

Step 3: Define ListIndexNotationPopulator.

 

ListIndexNotationPopulator.java

package com.sample.app;

import java.io.StringWriter;
import java.util.HashMap;
import java.util.Map;

import com.sample.app.util.FreeMarkerUtil;

public class ListIndexNotationPopulator {
	public static void main(String args[]) throws Exception {

		Map<String, Object> modelObject = new HashMap<String, Object>();
		
		StringWriter stringWriter = FreeMarkerUtil.mergeModelAndTemplate(modelObject, "listIndexNotation.ftl");
		System.out.println(stringWriter.toString().trim());

	}
}

Output

Value at 0th index 2

Value at 1st index 3

Value at 2nd index 5

Value at 3rd index 7

Value at 4th index 11

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