Understanding how to use JSP EL expressions to access properties of a Object

Question

I am new to J2EE development. I am unable to understand how/why this following code snippet works. The below class has the following problems:

1. The class has non-zero constructor.
   
2. "getname" accessor method is wrongly typed, it should be "getName".
3. There is no corresponding "setName" mutator method.

/* Java class  */

public class HelloBean {

    private String name = "Hello Bean";

    public HelloBean(String test) {
        this.name = test;
    }

    public String getname() {
        return this.name;
    }
}

// End of Java Class 
// Code in jsp page (only relevant code is shown)<br>

<%
    HelloBean test = new HelloBean("HelloWorld");
    pageContext.setAttribute("test", test);
%>

<p>The value=${test["name"]}</p

Output: (the below output is shown with no errors or exceptions thrown)

---

The value=HelloWorld

---

Test Environment: Tomcat 7 (jdk 1.6)

Answer 1

You pass the value for the HelloBean(String test) constructor. As your String name is the global variable for the class HelloBean. the syntax ${test["name"]} will interpret the name value.

It is equivalent to the java's ObjName.VariableName which will print its value.You could try it as ${name} which will throw InvalidProperyException on the setter and getter errors.

This Can JSP EL do direct attribute access might help