How can a class extend two classes in Java?

Question

If Java can only extend one class, and every class extends java.lang.Object, how can it extend another class? And how come every class doesn't have written extends Object?

Answer 1

If java can only extend one class, and every class extends java.lang.Object, how can it extend another class?

When you say A extends B then it means that A extends B and B extends Object. One class can inherit from another which can inherit from another and at the top of the chain is java.lang.Object. Java doesn't support multiple inheritance , but supports multi-level inheritance.

how come every class doesn't have written "extends Object" ?

All classes extend Object implicitly , so it will be redundant coding.