What are the differences between ${} and #{}?

Question

I\'m programming in JSF2 and NetBeans creates many pages with #{} that contains an expression. However sometimes on the web I found ${} for the sam

Answer 1

The Java documentation gives the following explanation:

${customer.name}
#{customer.name}

The former uses immediate evaluation syntax, whereas the latter uses deferred evaluation syntax. The first expression accesses the name property, gets its value, adds the value to the response, and gets rendered on the page. The same can happen with the second expression. However, the tag handler can defer the evaluation of this expression to a later time in the page lifecycle, if the technology using this tag allows.

In the case of JavaServer Faces technology, the latter tag’s expression is evaluated immediately during an initial request for the page. In this case, this expression acts as an rvalue expression. During a postback request, this expression can be used to set the value of the name property with user input. In this case, the expression acts as an lvalue expression.

Read more here: value expressions