if a value is not defined, or defined but not initialized, freemarker throws an exception for using it.
define the values in the java
package egtry.freemarker.datatype;
import java.io.StringWriter;
import java.util.HashMap;
import java.util.Map;
import freemarker.template.Configuration;
import freemarker.template.DefaultObjectWrapper;
import freemarker.template.Template;
public class MissingValue {
public static void main(String[] args) throws Exception {
Configuration config=new Configuration();
config.setClassForTemplateLoading(MissingValue.class, "");
config.setObjectWrapper(new DefaultObjectWrapper());
Map<String, Object> root=new HashMap<String, Object>();
Thing thing=new Thing();
//thing.setName("Name1");
thing.setAge(30);
root.put("thing", thing);
Template template=config.getTemplate("missing.ftl");
StringWriter out=new StringWriter();
template.process(root, out);
System.out.println(out.getBuffer().toString());
}
public static class Thing {
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
private String name;
private int age;
}
}
freemarker template
<#if thing.name??>
this line is optional. name: ${thing.name}
</#if>
age: ${thing.age}