After() in aspectj

Question

I am new to aspectj and I had a function which gets the integer variable and adds 100 to it as follows

public static void add(int no)
    {
        no=no+100;


    }

My aspect is as follows

pointcut printMessage(int m) : execution(* add(..)) && args(m);
 after(int m) returning: printMessage(m) {
            System.out.println(m);
}

I am calling the function with the value 10. But when I run the code, it returns the result as 10. can any one tell me why it is not returning 110. correct me if I am wrong

Answer 1

Because in java an int is not modifiable. If you write

int i = 10;
add(i);
System.out.println(i);

You will still get 10. So your aspect does what you asked : you pass a variable of value 10 to a function, the fuction does what it wants with its local copy, and on return the variable is unchanged

Edit :

If you want to get a modified value, you could pass a modifiable variable like an array, or more simply use the return value (because your current add is a no op) :

Edit 2 here is full test code :

public class AspectTest {
    public static int add(int i) {
        return i+100;
    }

    @Test
    public void test() throws Exception {
        int j = add(10);
        assertEquals(110, j);
        add(20);
    }
}

and :

aspect A {
pointcut printMessage() : execution(* add(..));
 after() returning (int m): printMessage() {
            System.out.println(m);
}
}

Output :

Running ...AspectTest
110
120
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.214 sec