Question

I want to create dynamic conditional statement in java
following are my expression in file,There are hundreds of expression and they keep on changing

0001|((condition1 == 100) && ((condition2 == 1) || (condition2 == 2) || (condition2 == 3)) && (condition3 > 74))
0002|((condition1 == 100) && ((condition2 == 1) || (condition2 == 2) || (condition2 == 3)) && (condition3 > 59) && ((condition4 == 3) || (condition5 > 30)))

These expression are hardcoded in my class.

if(condition1==100 && ((condition2 == 1) || (condition2 == 2) || (condition2 == 3))){

if(condition3>74){
return "0001"
}
if(condition3>59 && ((condition4 == 3) || (condition5 > 30))){
return "0002"
}

}

i want to create dynamic conditional statement like

first i have check for all expressions which have condition1==100
then for ((condition2 == 1) || (condition2 == 2) || (condition2 == 3))
then return value according to final condition

it is something like first DFS and then BFS

can some body can give me idea how to check first Depth and then Bredth First in java

Answer 1

Your case is : You want define very many conditions and change it continous. You need to have a solution for change dynamically expression and define new condition.

There are two solution for dynamic situation such as your case:

1. Using Rule Engine. This has very benefit, you can see more information from http://java.sun.com/developer/technicalArticles/J2SE/JavaRule.html
   and you can see its open source implementation from here .
2. Using Dynamic Language or Script Language and Script api.

in second solution you have several choise. I writing some in following:

• Groovy: A complete and wonderful script language. see http://groovy.codehaus.org/
• Spring Expression Language: Spring solution for calling simple expression. see http://static.springsource.org/spring/docs/3.0.5.RELEASE/reference/expressions.html
• BeanShell: A simple but wonderful script language.

There are more dynamic language such as JRuby that you can see it by simple searching in web.
You can read more information for Script api in java from here.

Edited:

For sample, you can use BeanShell Script Language as follwoing:

First create a file with name test.bsh containg blow contents:

if(variable_1 == 100 )
{
   System.out.println("Sample condition checked and is true.");
}
else
{
   System.out.println("Sample condition checked and is false.");
}

Second set variable_1 from java:

import bsh.*;

Interpreter bsh = new Interpreter ();
bsh.set ("variable_1", 100);

and in final call script as following:

 bsh.source (script);

and result will be as following:

Sample condition checked and is true.

by this approach you can change test.bsh content without recompile or restart.