Java – Rendering a nested list with JSP

javajspjstl

I need to render a 3-level deep list of items via JSP. Let's say I have beans with String properties "Country", "City", "Street". I need to build a heirarchy of UL and LI tags to show streets such that they are listed under the appropriate city, and such that each city is listed under the appropriate country.

Example:

<ul>
<li>United States
    <ul>
    <li>Washingron
            <ul>
        <li>Independence Ave</li>
        <li>23d Street</li>
        </ul>
    </li>
    <li>Detroit
        ...
    </li>
    </ul>
</li>
<li>United Kingdom
...
</li>
</ul>

Obviously, I could use forEach, but properly opening and closing tags for each list would require tons of if statements. Is there some simple way to do this via JSTL?

Best Answer

<ul>
<c:forEach items="${countriesList}" var="country"> 
   <li>${country.name}
      <ul>
         <c:forEach items="${country.stateList}" var="state">
            <li>${state.name}
                <ul>
                   <c:forEach items="${state.addressLines}" var="addressLine">
                      <li>${addressLine.addressString}</li>
                   </c:forEach>
                </ul>
            </li>
         </c:forEach>
      </ul>
   </li>
</c:forEach>
</ul>

Related Solutions

Java inner class and static nested class

From the Java Tutorial:

Nested classes are divided into two categories: static and non-static. Nested classes that are declared static are simply called static nested classes. Non-static nested classes are called inner classes.

Static nested classes are accessed using the enclosing class name:

OuterClass.StaticNestedClass

For example, to create an object for the static nested class, use this syntax:

OuterClass.StaticNestedClass nestedObject = new OuterClass.StaticNestedClass();

Objects that are instances of an inner class exist within an instance of the outer class. Consider the following classes:

class OuterClass {
    ...
    class InnerClass {
        ...
    }
}

An instance of InnerClass can exist only within an instance of OuterClass and has direct access to the methods and fields of its enclosing instance.

To instantiate an inner class, you must first instantiate the outer class. Then, create the inner object within the outer object with this syntax:

OuterClass outerObject = new OuterClass()
OuterClass.InnerClass innerObject = outerObject.new InnerClass();

see: Java Tutorial - Nested Classes

For completeness note that there is also such a thing as an inner class without an enclosing instance:

class A {
  int t() { return 1; }
  static A a =  new A() { int t() { return 2; } };
}

Here, new A() { ... } is an inner class defined in a static context and does not have an enclosing instance.

Java – How to create an executable JAR with dependencies using Maven

<build>
  <plugins>
    <plugin>
      <artifactId>maven-assembly-plugin</artifactId>
      <configuration>
        <archive>
          <manifest>
            <mainClass>fully.qualified.MainClass</mainClass>
          </manifest>
        </archive>
        <descriptorRefs>
          <descriptorRef>jar-with-dependencies</descriptorRef>
        </descriptorRefs>
      </configuration>
    </plugin>
  </plugins>
</build>

and you run it with

mvn clean compile assembly:single

Compile goal should be added before assembly:single or otherwise the code on your own project is not included.

See more details in comments.

Commonly this goal is tied to a build phase to execute automatically. This ensures the JAR is built when executing mvn install or performing a deployment/release.

<plugin>
  <artifactId>maven-assembly-plugin</artifactId>
  <configuration>
    <archive>
      <manifest>
        <mainClass>fully.qualified.MainClass</mainClass>
      </manifest>
    </archive>
    <descriptorRefs>
      <descriptorRef>jar-with-dependencies</descriptorRef>
    </descriptorRefs>
  </configuration>
  <executions>
    <execution>
      <id>make-assembly</id> <!-- this is used for inheritance merges -->
      <phase>package</phase> <!-- bind to the packaging phase -->
      <goals>
        <goal>single</goal>
      </goals>
    </execution>
  </executions>
</plugin>

Best Answer

Related Solutions

Java inner class and static nested class

Java – How to create an executable JAR with dependencies using Maven

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