Why Extends Before Implements Java?

Because the parent class must be compilable, it is easier if the compiler knows up front what that class is. Further, you can extend only one class but implement any number of interfaces. The compilation time climbs if the extends keyword can be intermingled amongst any number of implements instructions.

Should implements or extends first?

The extends always precedes the implements keyword in any Java class declaration. When the Java compiler compiles a class into bytecode, it must first look to a parent class because the underlying implementation of classes is to point to the bytecode of the parent class - which holds the relevant methods and fields.

What is the use of extends and implements in Java?

The keyword extends is used when a class wants to inherit all the properties from another class or an interface that wants to inherit an interface. We use the implements keyword when we want a class to implement an interface.