Here’s a useful Wicket i18n tip to reduce the amount of code you need to write. Any HTML tag in your HTML template can have a wicket:message attribute added to it. This is especially useful in <a> and <input> tags.

For example, if you want a tooltip to appear when you hover the mouse over an <a> tag, you will use the title attribute, like so:

<a
  href="#"
  title="Text to show on mouseover"
>click here</a>

However, this means that the user will see a tooltip in English regardless of their locale. The classic solution requires writing code in your Java component and using the AttributeModifier class to add a title attribute with a reference to StringResourceModel or ResourceModel.

Instead, you can use wicket:message:

<a
  href="#"
  wicket:message="title:LinkTitleKey"
>click here!</a>

It’s not necessary to include the attribute you are adding or replacing in your HTML template (in this example, title="" isn’t necessary). Wicket will overwrite it if it exists and will add it if it doesn’t exist.

The usage of wicket:message in this context is to specify the name of the attribute, followed by a colon, and then the resource key to look up (i.e., attribute:key). In this example, since we’re adding or modifying the title attribute, the syntax is title:LinkTitleKey.

You might sometimes need to specify multiple attributes. An example would be in an <input type="submit"> button, when you want to specify the text to display in the button (using the name attribute), but also define text to show in a mouseover tooltip (using the title attribute). Separate each attribute:key combination with a comma. For example:

<input
  type="submit"
  wicket:message="name:InputName,title=InputTitle"
/>

Then, in your resource file, define a values for your keys:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE properties SYSTEM
  "http://java.sun.com/dtd/properties.dtd">
<properties>
  <entry key="LinkTitleKey">Text to show on mouseover</entry>
  <entry key="InputName">Submit</entry>
  <entry key="InputTitle">Mouseover text</entry>
</properties>

Your resource file must exist in the same source directory as your HTML template and Java component. For example, if your page is named MyPage, you will have MyPage.java, MyPage.html, and MyPage.properties.xml.