正体不明のオブジェクトのクラスを調べるには？ J2SEのコアパッケージでも頻繁に利用されていますが，コレクションクラスを利用していると ...

Take a look at java.lang.Math, java.util.Arrays, and java.util.Collections; each is a utility class. These utilities group related methods on primitive values, arrays, and interfaces.

It doesn’t hurt anything to have both present just as it did not hurt anything to have both premain and agentmain methods defined in the object class.

Instance variables contain data associated with an object, such as its description, the types of messages it can receive, the objects it can receive messages from, and the objects it can send messages ...