头歌Java实验面向对象高级

第1关：类的继承和super关键字

package step1;
 
 
class Animal{
 
    String name;
    public void shout(){
        System.out.println(this.name + "发出叫声");
    }
 
    public Animal(String name) {
        this.name = name;
    }
}
 
// ---------------------Begin------------------------
//编写Dog类继承Animal类，重写shout方法，增加superShout方法
class Dog extends Animal{
    public Dog(String name) {
        super(name);
    }
 
    public void shout(){
        System.out.println(this.name+"发出汪汪叫");
    }
    public void superShout(){
        super.shout();
    }
}
 
 
// ---------------------End------------------------
 
 
 

第2关：final关键字改错

package step2;

// ---------------------Begin------------------------
 class Person{
        int age;
          String name;

    public void sayHello(){
        System.out.println("nice to meet you.");
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}
class  Student extends Person{

    @Override
    public void sayHello() {
        System.out.println(String.format("Hey nice to meet you. I am a student, my name is %s. I am %d years old.", this.name, this.age));
    }

}

// ---------------------End------------------------
public class FinalKeyWord {

    public static void main(String[] args) {
        Student student = new Student();
        student.setAge(18);
        student.setName("张三");
        student.sayHello();
    }
}

第3关：抽象类

package step3;
 
 
// ---------------------Begin------------------------
 
  abstract class Studenta {
 
abstract void sayHello();
}
class Student extends Person {
    String name="jack";
    int age=18;
    public Student(int age,String name){
        super(age,name);
    }
   public  void sayHello() {
        System.out.println(String.format("大家好，我叫%s，今年%d岁，很高兴认识大家", this.name,this.age));
    }
 
    public static void main(String[] args) {
Student s=new Student();
s.sayHello();
    }
}
 
// ---------------------End------------------------
 

第4关：接口

package step4;



// ---------------------Begin------------------------

 interface MyInterface{
   void sayHi();

}


 class InterfaceDemo implements Demo{
   public void show(){
       System.out.println("实现了接口中的show方法");
   }
}





// ---------------------End------------------------

第5关：多态

package step5;


// ---------------------Begin------------------------
class Cat extends Animal{
    public void shout(){
        System.out.println("小花猫喵喵叫");
    }
}
class Dog extends Animal{
    public void shout(){
        System.out.println("大黄狗汪汪叫");
    }
}

class Pig extends Animal{
    public void shout(){
        System.out.println("大胖猪喊喊叫");
    }
}






// ---------------------End------------------------

 class polymorphicDemo{
        public static void main(String[] args){
             Cat c = new Cat();
             Dog d = new Dog();
              method(c);
              method(d);
              method(new Pig());
        }
        public static void method(Animal a){
             a.shout();
        }
 }

第6关：匿名内部类

package step6;

abstract class Demo{
    abstract void show();
}

// ---------------------Begin------------------------

class Outer{
    public void show(){
        System.out.println("外部类调用show方法");
    }
    void method(){
        new Demo(){
              void show(){
                System.out.println("内部类调用show方法");
            } 
        }.show();
    }
}




// ---------------------End------------------------

第7关：Lambda表达式

package step7;
import java.util.Scanner;

interface Mycaculator{
    int add(int a, int b);
}

public class LambdaTest {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int a = scanner.nextInt();
        int b = scanner.nextInt();
        // ---------------------Begin------------------------
        //lambad表达式实现Mycaculator接口完成两数相加并打印输出结果
        Mycaculator calculator = (x,y)->x+y;
        int result = calculator.add(a,b);
        System.out.print(result);
        // ---------------------End------------------------

    }
}

第8关：异常处理

package step8;

public class ErrorHandle {
    public static void main(String[] args) {
        ErrorHandle errorHandle = new ErrorHandle();
        // ---------------------Begin------------------------
        //捕获errorSrc对象中divideTest方法中的除零异常（ArithmeticException）,获取异常信息可以使用getMessage方法
        try{
            errorHandle.divideTest();
        }
        catch (ArithmeticException e){
            System.out.println("Exception Messaage:"+e.getMessage());
        }
        finally {
            System.out.println("/ by zero");
            System.out.println("成功捕获除零异常");
        }
    }
public void divideTest() {
        try {
            int result = 0 / 1; 
        } 
        catch (ArithmeticException e) {
            System.out.println("Exception Message: " + e.getMessage());
            throw e; 
        }
    }
}

第9关：知识回顾

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