FreeMarker: Comparison Operators

== : Test for Equality

!= : Test for Inequality

< : Less Than Operator

<= : Less than or equal to

> : Greater than operator

>= : Greater than or equal to operator

 

Note

Freemarker can interpret >, >= are end of the tags. To prevent this use gt instead of > and gte instead of >=. You can even use lt instead of <, lte instead of <=,

 

Find the below working application.

 

Step 1: Create ‘conditionalOperators.ftl’ file under src/main/resources/templates folder.

 

conditionalOperators.ftl

<#assign a = 10, b = 11>

a : ${a}
b : ${b}

is a equals to a :  ${(a==a)?string}
is a equals to b : ${(a==b)?string}
is a not equals to a : ${(a!=a)?string}
is a not equals to b : ${(a!=b)?string}
is a less than a : ${(a<a)?string}
is a less than b : ${(a<b)?string}
is a less than or equal to a : ${(a<=a)?string}
is a less than or equal b : ${(a<=b)?string}
is a greater than a : ${(a>a)?string}
is a greater than b : ${(a>b)?string}
is a greater than or equal to a : ${(a>=a)?string}
is a greater than or equal to b : ${(a>=b)?string}

Step 2: Define ‘FreeMarkerUtil’ class that take model class 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 ‘ConditionalOperatorsPopulator.java’.

 

ConditionalOperatorsPopulator.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 ConditionalOperatorsPopulator {
  public static void main(String args[]) throws Exception {

    Map<String, Object> modelObject = new HashMap<String, Object>();

    StringWriter stringWriter = FreeMarkerUtil.mergeModelAndTemplate(modelObject, "conditionalOperators.ftl");
    System.out.println(stringWriter.toString().trim());

  }
}

Output

a : 10

b : 11

 

is a equals to a :  true

is a equals to b : false

is a not equals to a : false

is a not equals to b : true

is a less than a : false

is a less than b : true

is a less than or equal to a : true

is a less than or equal b : true

is a greater than a : false

is a greater than b : false

is a greater than or equal to a : true

is a greater than or equal to b : false

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