Re: Lambda expression question on Tomcat_8_0_15

2014-12-16 Thread Anup Aggarwal 
Thanks for the response ,

So the value itself is returned and not an ELExpression, The API said
A LambdaExpression is created when an EL expression containing a Lambda
expression is evaluated. So I figured that we will always get back a
LambdaExpression.

Now I am trying to print some values in the same case, and keep on getting
Null , any ideas what is wrong here,

protected void doGet... {
 ELProcessor elp = new ELProcessor();
sos.println(Test:  + (LambdaExpression)
(elp.eval(()-System.out.println(\Hello World\;
}



On Mon, Dec 15, 2014 at 4:20 PM, Mark Thomas ma...@apache.org wrote:

 On 15/12/2014 21:13, David Wall wrote:
  On 12/15/2014 12:19 PM, Anup Aggarwal wrote:
  Hi,
 
  I am new to learn the LambdaExpression , and I am trying to run a test
  with
  JDK7 on Tomcat_8_0_15 server
 
  Don't you need JDK8 for Lamdas?

 Not in this case, no. The EL 3.0 specification includes a form of lambda
 support and requires Java 7 or later.

 Mark


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Re: Lambda expression question on Tomcat_8_0_15

2014-12-16 Thread Mark Thomas 
On 16/12/2014 16:32, Anup Aggarwal wrote:
 Thanks for the response ,
 
 So the value itself is returned and not an ELExpression, The API said
 A LambdaExpression is created when an EL expression containing a Lambda
 expression is evaluated.

The Javadoc for ELProcessor.eval() says nothing of the sort.

 So I figured that we will always get back a LambdaExpression.

If you want to know what ELProcessor.eval() returns, read the Javadoc
for that method.

 Now I am trying to print some values in the same case, and keep on getting
 Null , any ideas what is wrong here,
 
 protected void doGet... {
  ELProcessor elp = new ELProcessor();
 sos.println(Test:  + (LambdaExpression)
 (elp.eval(()-System.out.println(\Hello World\;
 }

Are you paying any attention to the advice you are being given? You CAN
NOT cast the result of ELProcessor.eval() to LambdaExpression. You are
getting away with it because the expression you are evaluating is
returning null.

In terms of seeing Null in the ServletOutputStream that looks to be
entirely expected since the expression is calling a method that returns
void.

Mark


 On Mon, Dec 15, 2014 at 4:20 PM, Mark Thomas ma...@apache.org wrote:

 On 15/12/2014 21:13, David Wall wrote:
 On 12/15/2014 12:19 PM, Anup Aggarwal wrote:
 Hi,

 I am new to learn the LambdaExpression , and I am trying to run a test
 with
 JDK7 on Tomcat_8_0_15 server

 Don't you need JDK8 for Lamdas?

 Not in this case, no. The EL 3.0 specification includes a form of lambda
 support and requires Java 7 or later.

 Mark


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 To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org
 For additional commands, e-mail: users-h...@tomcat.apache.org


 


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Lambda expression question on Tomcat_8_0_15

2014-12-15 Thread Anup Aggarwal 
Hi,

I am new to learn the LambdaExpression , and I am trying to run a test with
JDK7 on Tomcat_8_0_15 server

protected void doGet... {
 ELProcessor elp = new ELProcessor();
sos.println(Test:  + (LambdaExpression) elp.eval(()-64));
}

But I always get this error

java.lang.ClassCastException: java.lang.Long incompatible with
javax.el.LambdaExpression



I have also tried passing an empty array in the invoke() per the API

Object[] empty_array = {};
sos.println(Test:  + ((LambdaExpression)
elp.eval(()-64)).invoke(empty_array));

Same Exception,
java.lang.ClassCastException: java.lang.Long incompatible with
javax.el.LambdaExpression


Can someone help and tell me what I am doing wrong.


Thanks,

Re: Lambda expression question on Tomcat_8_0_15

2014-12-15 Thread Mark Thomas 
On 15/12/2014 20:19, Anup Aggarwal wrote:
 Hi,
 
 I am new to learn the LambdaExpression , and I am trying to run a test with
 JDK7 on Tomcat_8_0_15 server
 
 protected void doGet... {
  ELProcessor elp = new ELProcessor();
 sos.println(Test:  + (LambdaExpression) elp.eval(()-64));
 }
 
 But I always get this error
 
 java.lang.ClassCastException: java.lang.Long incompatible with
 javax.el.LambdaExpression

You are trying to cast the result of the LambaExpression which is a Long
to LambdaExpression which isn't going to work. Just remove the cast.

 I have also tried passing an empty array in the invoke() per the API
 
 Object[] empty_array = {};
 sos.println(Test:  + ((LambdaExpression)
 elp.eval(()-64)).invoke(empty_array));
 
 Same Exception,
 java.lang.ClassCastException: java.lang.Long incompatible with
 javax.el.LambdaExpression
 
 Can someone help and tell me what I am doing wrong.

Same error as above.

Mark


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Re: Lambda expression question on Tomcat_8_0_15

2014-12-15 Thread David Wall 

On 12/15/2014 12:19 PM, Anup Aggarwal wrote:

Hi,

I am new to learn the LambdaExpression , and I am trying to run a test with
JDK7 on Tomcat_8_0_15 server


Don't you need JDK8 for Lamdas?


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Re: Lambda expression question on Tomcat_8_0_15

2014-12-15 Thread Mark Thomas 
On 15/12/2014 21:13, David Wall wrote:
 On 12/15/2014 12:19 PM, Anup Aggarwal wrote:
 Hi,

 I am new to learn the LambdaExpression , and I am trying to run a test
 with
 JDK7 on Tomcat_8_0_15 server
 
 Don't you need JDK8 for Lamdas?

Not in this case, no. The EL 3.0 specification includes a form of lambda
support and requires Java 7 or later.

Mark


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