How does Java expression language resolve boolean attributes? (in JSF 1.2)

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It’s authoritatively documented in both the JavaBeans Spec and EL Specification.

To take the boolean property as an example, it’s described in chapter 8.3.2 of JavaBeans spec:

8.3.2 Boolean properties

In addition, for boolean properties, we allow a getter method to match the pattern:

public boolean is<PropertyName>();

This “is<PropertyName>” method may be provided instead of a “get<PropertyName>” method,
or it may be provided in addition to a “get<PropertyName>” method.

In either case, if the “is<PropertyName>” method is present for a boolean property then we will
use the “is<PropertyName>” method to read the property value.

An example boolean property might be:

    public boolean isMarsupial();
    public void setMarsupial(boolean m);

So, #{bean.marsupial} expects exactly the above getter/setter pair.

And in chapter 1.23.5 of EL spec:

1.23.5 Coerce A to Boolean or boolean

  • If A is null and the target type is not the primitive type boolean, return null
  • If A is null or "", return false
  • Otherwise, if A is a Boolean, return A
  • Otherwise, if A is a String, and Boolean.valueOf(A) does not throw an
    exception, return it
  • Otherwise, error

See also:

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