How can I use Java reflection to invoke a method on a reference variable?

Question

Class X is being used inside class Y. Class X has a function xMethod that is not used inside class Y. Can I use reflection on Class Y to invoke the xMethod on Y's xInternalVar?How?

class X  {
    void xMethod (){ 
    //some code
}

class Y {
    X xInternalVar = new X();
}

Possible duplicate thread: http://stackoverflow.com/questions/160970/how-do-i-invoke-a-java-method-when-given-the-method-name-as-a-string — Eldar Agalarov, Aug 13 '13 at 17:45

score 3 · Accepted Answer · answered Aug 13 '13 at 17:03

Yes - you've just got two steps here:

Fetch the value of xIntervalVar - use Class.getDeclaredField to get at the relevant field in Y, then get the value of it for the relevant instance of Y
Call xMethod on the instance of X - use Class.getDeclaredMethod to get at the relevant method in X, then invoke the method using the value returned by step 1.

How can I use Java reflection to invoke a method on a reference variable?

1 Answers1