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This is done using two special Wicket tags: <wicket:child> and <wicket:extend>. In the super markup you define where the child markup should be put, and in the sub markup you delineate where the child markup starts and ends.

Code Block

	html
	html
title	The super markup file
borderStyle	solid

<html>
<head></head>
<body>
This is in the super markup.<br>
<wicket:child />
This is in the super markup.<br>
</body>
</html>

In this markup you see two sentences that surround the wicket:child tag. All markup in this file will remain when a sub class of this page is created, only the wicket:child tag will be replaced with the child markup. So if we look at the following markup:

Code Block

	html
	html
title	The child markup file
borderStyle	solid

<html>
<head></head>
<body>
This is in de child markup.<br>
<wicket:extend>
This is in the child markup.<br>
</wicket:extend>
This is in the child markup.<br>
</body>
</html>

we can see the markup that should be included in the parent. Only the markup between the wicket:extend tags is included in the final page. Take a look at the following markup which is the final markup when you would use this in a Wicket application.

Code Block

	html
	html
title	The final markup rendered to the browser
borderStyle	solid

<html>
<head></head>
<body>
This is in the super markup.<br>
<wicket:child><wicket:extend>
This is in the child markup.<br>
</wicket:extend></wicket:child>
This is in the super markup.<br>
</body>
</html>

...

Now that we have seen the basics for markup inheritance, we can now take a look at the example at hand. Let's first create the base page.

Code Block

	java
	java
title	The base page's Java class
borderStyle	solid

package wicket.quickstart;

import wicket.markup.html.WebPage;
import wicket.markup.html.basic.Label;
import wicket.markup.html.link.BookmarkablePageLink;

public abstract class BasePage extends WebPage {
	public BasePage() {
		add(new BookmarkablePageLink("page1", Page1.class));
		add(new BookmarkablePageLink("page2", Page2.class));
		add(new Label("footer", "This is in the footer"));
	}
}

The two links should go into the header, and the footer in the footer of the page. Note that the abstract keyword isn't required, but considered a good practise. Now let's take a look at the markup for the BasePage

Code Block

	html
	html
title	The base page's markup file
borderStyle	solid

<html>
<head></head>
<body>
<div id="header">
    <a href="#" wicket:id="page1">Page1</a>
    <a href="#" wicket:id="page2">Page2</a>
</div>
<div id="body">
<wicket:child />
</div>
<div id="footer">
	<span wicket:id="footer"></span>
</div>
</body>
</html>

...

We need to build two pages: Page1 and Page2. Each page needs its own markup file and Java class. Let's first implement Page1.

Code Block

borderStyle

	java
	java
title	Page1's Java class
	solid

package wicket.quickstart;

import wicket.markup.html.basic.Label;

public class Page1 extends BasePage {
	public Page1() {
		add(new Label("label1", "This is in the subclass Page1"));
	}
}

In this example you see that we add a new label component to the page: label1. This component is only available for Page1, as such Page2 can define its own component hierarchy. Let's take a look at the markup for Page1:

Code Block

	java
	java
title	Page1's markup file
borderStyle	solid

<html>
<head></head>
<body>
<wicket:extend>
<h1>Page1</h1>
<span wicket:id="label1"></span>
</wicket:extend>
</body>
</html>

...

Now, let's do the same for Page2.

Code Block

	java
	java
title	Page2's Java class
borderStyle	solid

package wicket.quickstart;

import wicket.markup.html.basic.Label;

public class Page2 extends BasePage {
	public Page2() {
		add(new Label("label2", "This is in the subclass Page2"));
	}
}

Code Block

	html
	html
title	Page2's markup file
borderStyle	solid

<html>
<head></head>
<body>
<wicket:extend>
<h1>Page2</h1>
<span wicket:id="label2"></span>
</wicket:extend>
</body>
</html>

...

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