Java class by default, it will implicitly extend java.lang.Object [duplicate]

Answer 1

• Every class, except for java.lang.Object, extends exactly one class.
• If you write extends Something, then your class extends Something.
• If you don't write extends Something, then your class extends java.lang.Object. (the same as if you wrote extends Object)

Answer 2

If you don't extend any class, you will still extend Object. If you explicitely extend some class, than you extend just this class, but the extended class will in other turn extend Object by default. This way Object is always in class hierarchy.