Java multiple objects as an argument to a function

Question

Java multiple objects as an argument to a function

I have a function in a java class that calls triggers on an action listener (as shown below):

// action event fired when hitting a checkbox
public void fireActionCheckBox(MyMainClass frame, JCheckBox theButtonExample) {

    for(ActionListener a: theButtonExample.getActionListeners()) {
        a.actionPerformed(new ActionEvent(this, ActionEvent.ACTION_PERFORMED, null) {
              //Nothing need go here, the actionPerformed method (with the
              //above arguments) will trigger the respective listener
        });
    }
}

Then I have a second function that does the same for the JButton action listener:

// action event fired when hitting a button
public void fireActionButton(MyMainClass frame, JButton theButtonExample) {

    for(ActionListener a: theButtonExample.getActionListeners()) {
        a.actionPerformed(new ActionEvent(this, ActionEvent.ACTION_PERFORMED, null) {
              //Nothing need go here, the actionPerformed method (with the
              //above arguments) will trigger the respective listener
        });
    }
}

I understand that in java, arguments must be assigned before they start, but it is inefficient to write the same code twice. Is there a better way to do this, they will prevent me from writing two functions for an action that looks so similar.

Thanks for your help!

+3

java function object arguments

JFreeman Apr 27. 17 at 6:34 am

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3 answers

You can pass a generics parameter to the method instead of JCheckBox theButtonExample

and JButton theButtonExample

. For example, suppose both classes extend the same parent, you could do

public <J extends commonParent> void fireActionButton(MyMainClass frame, J j) {
  //...
}

As @Sweeper pointed out in the comments, since the parent doesn't have a listener, you need to check the type and downcast :

public <J extends JComponent> void fireActionButton(MyMainClass frame, J j) {
  if (j instanceof JComboBox) {
    JCheckbox jbox = (JComboBox)j;
    // Do something else
  }
}

+2

PhoenixPan Apr 27. 17 at 6:41

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both JCheckBox and JButton are child parents of the same parent class:

define a method with the superclass of both:

public void fireActionAbstractButton(MyMainClass frame, AbstractButton myAbstractButton) {
        System.out.println(myAbstractButton.getClass().getName());
    }

+1

ΦXocę 웃 Pepeúpa ツ Apr 27. 17 at 6:47 am

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Andrew · Accepted Answer · 2017-04-27T06:45:24+0000

public void fireActionCheckBox(MyMainClass frame, AbstractButton button) { ... }

There is an abstract class AbstractButton

that is the parent of both of these classes. He defined the method getActionListeners

.

Alternatively, you can rewrite the method in a more general way:

public <T extends AbstractButton> void fireActionButton(MyMainClass frame, T button) { ... }

Java multiple objects as an argument to a function

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