Question

Several answers regarding overriding equals() and hashCode() describe the need for both and the application of using them as keys in a HashMap in Java. My question is, is the Java KeyStroke class safe to put as a key in a HashMap? Further, so I’m not annoying and continue to ask these questions, how would one find out if a provided class (I think KeyStroke is provided by Swing) is safe to use in this context…i.e. overrides equals() and hashCode()?

thanks in advance!

Answer 1

The way to see if equals and hashCode are overridden is to take a look at the API. hashCode and equals are not overridden in KeyStroke, but they are in AWTKeyStroke. In fact, AWTKeyStroke#hashCode states:

[this object is] a good choice as the index value in a hash table.