first, this is not similar to other questions because expressions contains parameters.
assume we have this method:
public static int test(int x, Double y) {
return somthing
}
and we have string expression like this:
String expression = "test(1, 2)";
so how can we run this expression ?
I want to write a method with parameter and call it from a expression .
I can't find any library to solve this problem.
please help
You can use the Script Engine with a scripting language, such as JavaScript, to handle your expressions.
package expression;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
public class App
{
public static void main( String[] args )
{
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("nashorn");
try {
engine.eval("var test = Packages.expression.App.test");
Object result = engine.eval("test(1,2)");
System.out.println(result);
} catch (ScriptException e) {
//TODO: handle exception
e.printStackTrace();
}
}
public static int test(int x, Double y) {
return x;
}
}
The line "var test = Packages.expression.App.test" creates an alias to your method.
The line Object result = engine.eval("test(1,2)"); calls your method.
You need to include the following dependency to your maven pom.xml:
<dependency>
<groupId>org.openjdk.nashorn</groupId>
<artifactId>nashorn-core</artifactId>
<version>15.1</version>
</dependency>
