how can I store an arraylist of void methods

Question

Is it possible to store void type methods in an arrayList or can you only store methods that have a return value? I want to call any one of up to 15 methods and rather than write:

if(var == 1){
    method1()
}else if(var ==2){
    method2();
}

etc...

by the time you surround with try/catch and a few more lines of code (that repeat for each one) it would be much neater if you could do:

arrayList.get(var); //or something similar

However my methods just "do stuff" as opposed to return a value so if the methods themselves cannot be stored in an array is there somewhere else they can be stored together and extracted with a for loop or by just using the "var" integer?

Is [this](http://stackoverflow.com/questions/1073358/function-pointers-in-java) what you need? — tommyo, Oct 23 '13 at 20:40

score 0 · Answer 1 · answered Oct 23 '13 at 21:46

0

What you are asking for is given precisely by

java.util.ArrayList<java.lang.reflect.Method>

but it seems to me you should be using a switch statement.

answered Oct 23 '13 at 21:46

user207421

298,294
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score 0 · Answer 2 · edited Feb 12 '20 at 15:36

0

To anyone who comes to look at this post 6 years later like I was, I suggest you have your ArrayList return a String of "". If the value is not used, it wont matter whether it's there or not, but you'll need it to make the compiler happy.

edited Feb 12 '20 at 15:36

alyssaeliyah

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answered Feb 12 '20 at 14:49

Ethan Thiede

9
1

score -1 · Accepted Answer · answered Oct 23 '13 at 20:41

-1

You cannot store method references in Java.

However, you can create an object of a class that has a defined interface that allows you to invoke the method readily.

public interface VoidMethod {
  public void callMethod();
}

// ...

public class Method1 implements VoidMethod {
  public void callMethod() {
    // your stuff here
  }
}

// ...

public class MethodN implements VoidMethod {
  public void callMethod() {
    // your stuff here
  }
}

Then you can populate an object array with instances of VoidMethod.

answered Oct 23 '13 at 20:41

Bob Dalgleish

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Of course you can store method references, by getting a Method object reference. The more tricky part is getting the Method object reference you want, usually by reflection. Of course what you suggested is otherwise a reasonable suggestion, just factually wrong. – Kevin Welker Oct 23 '13 at 21:20

how can I store an arraylist of void methods

3 Answers3