Java语言的三大特点，java的三大特征详解

**JAVA是什么： **
面向对象的三大特征：封装，继承，多态
封装：就是把数据封装起来，让外界无法进行访问，一般用private修饰
用set和get方法进行属性的设置和获取

public class Student {private String name;//设置属性并且私有化private String sex;private int age;public Student() {//无参的构造方法super();// TODO Auto-generated constructor stub}public Student(String name, String sex, int age) {//构造方法super();this.name = name;this.sex = sex;this.age = age;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}@Overridepublic String toString() {//打印属性return "Student [name=" + name + ", sex=" + sex + ", age=" + age + "]";}}

	。继承：子类具有父类相同的属性和方法，并且对父类的方法进行重写。修饰词extends。

public class animal {private String name;private String sex;private int age;public animal() {}public animal(String name) {this();this.name=name;System.out.println("父类的无参构造方法"+name);}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public void eat() {System.out.println("吃东西");}public void run() {System.out.println("在奔跑");}
}class Cat extends animal {public Cat() {System.out.println("子类无参的构造方法----");}public Cat(String name) {super("汤姆猫");System.out.println("子类的有参的构造方法");}
}class Dog extends animal {}```public class animaltest {public static void main(String[] args) {Cat cat=new Cat();	String name=cat.getName();System.out.println(name);//cat.run();//cat.eat();
//		Dog dog=new Dog();
//		dog.run();}
}多态：一种事物的多种形态，父类的引用指向子类的对象。```java
public class Car {String name="车";private double price;public Car() {}public Car(String name, double price) {this.name = name;this.price = price;}	public String getName() {return name;}public void setName(String name) {this.name = name;}public double getPrice() {return price;}public void setPrice(double price) {this.price = price;}public void run() {System.out.println("行驶中----");}public void piaoyi() {System.out.println(name+"飘移--------");}
}
class Aodi extends Car{String name="奥迪";private double price;public void run() {System.out.println(name+"我的速递是第一的");}}
class Baoma extends Car{String name="宝马";private double price;@Overridepublic void run() {System.out.println(name+"你不行，，，，我的速度是第一的");}
}

public class CarTest {
public static void main(String[] args) {
Car car=new Aodi();//父类的应用指向子类的对象
car.run();
car.piaoyi();
Car car1=new Baoma();
car1.run();
}
}