interface in java
An interface is a special kind of class that cannot be instantiated.
The main idea of an interface is declaring functionality. Interfaces help to
abstract from specific classes and emphasize the functionality.
It makes software design more reusable and clean
Opposite to a class, an interface can extend several interfaces.
A class can implement multiple interfaces.interface in java
In many cases, it is more important to know what an object can do,instead of
how it does what it does. This is a reason why interfaces are commonly used for
declaring a type of variable.
interface : DrawingTool : a tool can draw
interface DrawingTool {
void draw(Curve curve);
}
DrawingTool pencil = new Pencil();
DrawingTool brush = new Brush();
Both Pencil and brush class should implement draw methodinterface in java
interface Interface {
int INT_CONSTANT = 0; // it's a constant, the same as public static final int INT_FIELD = 0
void instanceMethod1();
void instanceMethod2();
static void staticMethod() {
System.out.println("Interface: static method");
}
default void defaultMethod() {
System.out.println("Interface: default method. It can be overridden");
}
private void privateMethod() {
System.out.println("Interface: private methods in interfaces are acceptable but should have a body");
}
}
Static, default, and private methods should have an implementation in the interface!do you have to implement all methods of an interface java
Yeah, unless the class is declared as an abstract class.Copyright © 2021 Codeinu
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