Android menuitem onclick handler's return value

问题

In android when I define a menuitem's onclick handler in xml

<item
    android:id="@+id/context_menu"
    android:orderInCategory="100"
    android:showAsAction="never"
    android:title="@string/word_context_menu_title"
    android:onClick="deleteItem"/>

And in the corresponding activity I define a function deleteItem with the below signature.

public boolean deleteItem(MenuItem item){
    logger.info("delete button clicked");
    return false;
}

My question is what does the return value signify? In which case should I return true and in which case should I return false?

回答1:

What the boolean return value means from the documentation of onMenuItemClick:

Return true to consume this click and prevent others from executing.

So similar behaviour to onOptionsItemSelected with the answer here. If I understand it correctly, this means that whenever you have successfully handled the event, you should return true.

---

Here's an example.

Say you have your deleteItem and also onOptionsItemSelected.

public boolean deleteItem(MenuItem item){
    Log.v("test", "delete button clicked");
    return false;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId())
    {
        case R.id.context_menu:
            Log.v("test","onOptionsItemSelected");
            return true;
        default:
            return super.onOptionsItemSelected(item);
    }
}

If you return false in deleteItem you will see that it is also handled in onOptionsItemSelected.

>delete button clicked
>onOptionsItemSelected

If you return true in deleteItem it will no longer be handled in onOptionsItemSelected.

>delete button clicked

Also note that your deleteItem handle can be a void method and it will automatically return true as per the source code here.

来源：https://stackoverflow.com/questions/23170715/android-menuitem-onclick-handlers-return-value