Java中的抽象类可帮助用户实现抽象，这是在软件设计过程中遵循的最关键的面向对象编程实践。

什么是Java中的抽象类？

Java中的抽象类充当实现方法及其功能之间的边界。
它用于在Concrete类成员和Abstract类之间交换功能。

抽象类被认为是那些向用户隐藏"方法实现"详细信息并仅显示"方法功能"的类。
它们使用关键字abstract声明。
这些方法中可以包括摘要方法和非摘要方法。

为什么我们需要Java中的抽象类？

由于以下原因，我们需要Java中的抽象类：

• 抽象类在运行时支持动态方法解析

• 它们帮助用户实现松散耦合

• 抽象类将方法定义与继承的子类分开

• 它们为所有子类提供了已定义方法的默认功能。

• 抽象类为将来的特定类提供模板

• 抽象类允许代码重用

在Java中使用抽象类的规则

要使用Java实现抽象类，我们需要遵循以下规则：

• 必须使用abstract关键字声明一个抽象类。

• 抽象类可以包括抽象和非抽象方法。

• 不能实例化Abstract类。

• 它们可以包括构造函数和静态方法。

• 抽象类包括最终方法。

用Java实现抽象的方法

Java中的抽象过程可以通过以下两种方法来实现，如下所述：

• 实现抽象类

• 实施接口

抽象类的语法

定义抽象类和抽象方法的语法如下：

abstract class theitroad{}

abstract class Method();

抽象类的实际例子

//抽象类

package Abstract;
public abstract class Person {
      private String name;
      private String gender;
      public Person(String nm, String gen) {
            this.name = nm;
            this.gender = gen;
      }
      public abstract void Studying();
      @Override
      public String toString() {
           return "Name=" + this.name + "::Gender=" + this.gender;
      }
}

//学生班

package Abstract;
public class Student extends Person {
      private int StudentID;
      public Student(String nm, String gen, int id) {
            super(nm, gen);
            this.StudentID = id;
      }
      @Override
      public void Studying() {
            if (StudentID == 0) {
                  System.out.println("Not Studying");
            } 
            else {
                 System.out.println("Pursuing a Degree in Bachelor of Engineering");
            }
      }
      public static void main(String args[]) {
            Person student = new Student("Priya", "Female", 0);
            Person student1 = new Student("Karan", "Male", 201021);
            Person student2 = new Student("Kumari", "Female", 101021);
            Person student3 = new Student("John", "Male", 201561);
            student.Studying();
            student1.Studying();
            student2.Studying();
            student3.Studying();
            System.out.println(student.toString());
            System.out.println(student1.toString());
            System.out.println(student2.toString());
            System.out.println(student3.toString());
      }
}

Not Studying
Pursuing a Degree in Bachelor of Engineering
Pursuing a Degree in Bachelor of Engineering
Pursuing a Degree in Bachelor of Engineering
Name=Priya::Gender=Female
Name=Karan::Gender=Male
Name=Kumari::Gender=Female
Name=John::Gender=Male

接口和抽象类之间的区别

//抽象类示例

package abstactVSinterface;
abstract class Shape {
      String objectName = " ";
      Shape(String name) {
            this.objectName = name;
      }
      abstract public double area();
      abstract public void draw();
}
class Rectangle extends Shape {
      int length, width;
      Rectangle(int length, int width, String name) {
            super(name);
            this.length = length;
            this.width = width;
      }
      @Override
      public void draw() {
            System.out.println("Rectangle is drawn ");
      }
      @Override
      public double area() {
            return (double) (length * width);
      }
}
class Circle extends Shape {
      double pi = 3.14;
      int radius;
      Circle(int radius, String name) {
            super(name);
            this.radius = radius;
      }
      @Override
      public void draw() {
            System.out.println("Circle is drawn ");
      }
      @Override
      public double area() {
            return (double) ((pi * radius * radius)/2);
      }
}
class theitroad {
      public static void main(String[] args) {
            Shape rect = new Rectangle(20, 30, "Rectangle");
            System.out.println("Area of rectangle: " + rect.area());
            Shape circle = new Circle(20, "Cicle");
            System.out.println("Area of circle is: " + circle.area());
      }
}

Area of rectangle: 600.0
 Area of circle is: 628.0

//接口示例

package absVSint;
interface Shape {
      void draw();
      double area();
}
class Rectangle implements Shape {
      int length, width;
      Rectangle(int length, int width) {
            this.length = length;
            this.width = width;
      }
      @Override
      public void draw() {
            System.out.println("Rectangle has been drawn ");
      }
      @Override
      public double area() {
            return (double) (length * width);
      }
}
class Circle implements Shape {
      double pi = 3.14;
      int radius;
      Circle(int radius) {
            this.radius = radius;
      }
      @Override
      public void draw() {
            System.out.println("Circle has been drawn ");
      }
      @Override
      public double area() {
            return (double) ((pi * radius * radius)/2);
      }
}
class theitroad {
      public static void main(String[] args) {
            Shape rect = new Rectangle(20, 30);
            System.out.println("Area of rectangle: " + rect.area());
            Shape circle = new Circle(20);
            System.out.println("Area of circle: " + circle.area());
      }
}

Area of rectangle: 600.0
Area of circle: 628.0