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Examples
Hello world basic java velocity Example How to use string as velocity template data with Example How to use Input stream or BLOB binary stream as velocity template file with Example How to use list object with foreach in Java Velocity Example How to use HashMap in Java velocity template with Example How to use Nested for loop in Java velocity with Example How to use If statement in Java velocity with Example
Examples [cont'd]
How to use Else-If ladder in Java velocity with Example How to use For loop in Java velocity with Example How to use #break in foreach of Java apache velocity with Example How to use #continue in foreach of Java apache velocity with Example How to use Single line and Multiline Comment in Java apache velocity with Example How to use expressions with #set method of java apache velocity with Example How to use Java Class in apache velocity template engine with Example
Examples [cont'd]
How to include vm file into another vm file in java apache velocity with Example How to create methods in Java apache velocity using #macro with Example How to escape velocity template reserved words or keywords in .vm with Example How to exit from the velocity template language execution using #stop with Example How to use arithmetic expressions in java apache velocity with Example How to use not specified velocity context variable value as empty in VTL with Example
How to use not specified velocity context variable value as empty in VTL with Example
7706 Views
$!{identifier} 
In VTL Output returns variable name with dollar. If velocity context is not added with the velocity context MapValueList.

Instead of using
$username
This will return $username as output when value not specified for username context.

Use
$!username or $!{username}
If username not in velocity context also this takes empty string as input.
Example
import java.io.StringWriter;

import org.apache.velocity.Template;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.VelocityEngine;

public class Example {
    public static void main(String args[]){
        VelocityEngine ve = new VelocityEngine();
        ve.init();
         
        Template t = ve.getTemplate("velocitytemplate.vm");
         
        VelocityContext vc = new VelocityContext();
        
        StringWriter sw = new StringWriter();
        t.merge(vc, sw);
         
        System.out.println(sw);
    }
}
Velocitytemplate.vm 
UserDetails
-----------
Username is $username.
Username is $!username.
Username is $!{username}.
Output 
UserDetails
-----------
Username is $username.
Username is .
Username is .
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