What are the characteristics of abstract classes

The characteristics of abstract classes are: 1. Both abstract classes and abstract methods need to be modified with abstract; 2. There can be no abstract methods in abstract classes, but abstract methods must be in abstract classes; 3. Abstract classes cannot directly Create objects; 4. Abstract classes have construction methods.

Characteristics of abstract classes:

(Recommended learning: java entry program)

1 , both abstract classes and abstract methods need to be modified with abstract;

2. Abstract methods must be in abstract classes, and there can be no abstract methods in abstract classes;

3. Abstract classes cannot directly create objects. (Instantiation);

4. If a subclass of an abstract class overrides all abstract methods, it will be a concrete class;

(Video tutorial recommendation: java video tutorial)

5. If the subclass of an abstract class does not override all abstract methods, then the subclass is still an abstract class;

6. The abstract class has a construction method, which is intended to allow the subclass to To call the constructor initialization;

Code example:

abstract class Emoplyee {
String name;
public Emoplyee(String name) {
this.name = name;
}
public void test() {
}
public abstract void work();
// public abstract void sleep();
}
class Waiter extends Emoplyee {
public Waiter(String s) {
super(s);
}
public void work() {
System.out.println("我来搽桌子");
}
}

The above is the detailed content of What are the characteristics of abstract classes. For more information, please follow other related articles on the PHP Chinese website!