面向对象10个案例 （来源网络）

class Anthropoid    //类人猿
{
    private int n=100;
    void crySpeak(String s)
    {
        System.out.println(s);
    }
}
class People extends Anthropoid
{
    void computer(int a,int b)
    {
        int c=a*b;
        System.out.println(c);
    }
    void crySpeak(String s)
    {
        System.out.println("**"+s+"**");
    }
}
public class Monkey
{
    public static void main(String args[])
    {
        Anthropoid monkey=new People();  
        //monkey是People对象的上转型对象
        //monkey.computer(10,10);      //非法
        monkey.crySpeak("我喜欢这个运动");
        People people=(People)monkey;     
        //把上转型对象强制转化为子类的对象
        people.computer(10,10);
    }
}




2
class ManyArea{
 public double area(double radius){
   return Math.PI*radius*radius;
   }
  public double area(double len,double width){
   return len*width;
   }
  public double area(int len,int width){
   return len*width;
   }
   public double area(double len,double width,double height){
   return len*width*height;
   }
  }
 public class OverLoad{
  public static void main(String args[]){
    ManyArea ob=new ManyArea();
    System.out.println("半径为3.0的圆的面积："+ob.area(3.0));
    System.out.println("长2.0、宽3.0的面积："+ob.area(2.0,3.0));
    System.out.println("长2、宽3的面积："+ob.area(2,3));
    System.out.println("立方体的面积："+ob.area(2.0,3.0,4.0));
    }
}



3
class Animal 
{
    public void shout() 
    {

    }
}
class Dog extends Animal 
{
    public void newDog()
    {
        System.out.println("Dog的新特性");
    }
    public void shout() 
    {
        System.out.println("汪");
    }
}
class Cat extends Animal 
{
    public void shout() 
    {
        System.out.println("喵");
    }
}
class Test
{
    public void animalshout(Animal a) 
    {
        a.shout();
    }
}
public class PolyEx
{
    public static void main(String[] args)
    {
        Animal d=new Dog();//(1)
        Dog d1= (Dog)d;//(3)父类对象强制转换成子类对象
        d1.newDog();
        //d.newDog();
        d.shout();
        Test t=new Test();
        t.animalshout(d);//(2)
        t.animalshout(d1);
    }
}


4
class ArrayEx{

    public  int[] subarray(int a[],int start,int end){

     int subarr[] = new int[end-start];

     for(int i=0,j=start;j<end;i++,j++){
         subarr[i] = a[j];

         }
     return subarr;
     }


}


public class Test{

 public static void main(String args[]){
     ArrayEx arrex = new ArrayEx();

     int arr[] = new int[10];
     for(int i = 0;i<arr.length;i++){

         arr[i] = i+10;

         }

     int sub[] = arrex.subarray(arr,2,6);
     for(int temp:sub){
         System.out.println(temp);
         }
     }

}

5
class Box{
  int length;
  int width;
  int height;
  
  void set(int len,int wid,int hei){
    length = len;
    width = wid;
    height = hei;
  }


}

class ShowBox{

   void show(Box b){
   
      System.out.println(b.length+" "+b.width+"  "+b.height);
   
   
   }

}

class TestTwo{
  public static void main(String args[]){
  
    Box a = new Box();
    a.set(3,4,5);
    
    ShowBox sbox = new ShowBox();
    sbox.show(a);
  }


}


6.
class One{
  int a = 5;

  void showB(){

    int a = 3;
    int b = this.a;
    System.out.println("b = "+b);

  }


}

public class ThisOne{

  public static void main(String args[]){

    One test = new One();
    test.showB();

  }



}

7.
class Mystatic{
  private  int x=3;


  public static void showx(){
    System.out.println("x="+x);
    }

  public static int add(int m){
    return m+x;
    }
   }



 class UseMystatic{
   public static void main(String args[]){
     Mystatic.showx();
    
     System.out.println("add="+Mystatic.add(2));
    
    
     }
     }

8.
class Point 
{
    int x;
    int y;

    Point(){
      x=0;
      y=0;
      //this(1,1);
    }

    Point(int a,int b){
      x=a;
      y=b;
    }

    void show(){
      System.out.println("x="+x+"  y="+y);
    }
}

public class UsePoint
{
    public static void main(String args[]){
      Point p = new Point();
      p.show();
    
    }
}

9.
 class Point{
    private int x,y;
    
    Point(){
      x=1;
      y=3;
     }
     
    void showPoint(Point t){
      System.out.println("x="+t.x+"   y="+t.y);
      }

    void seeit(){
      showPoint(this);
      }
  }


public class UsePointThis
{
    public static void main(String args[]){
        Point p=new Point();
        p.seeit();
    }
}

10
class Point{
    static int x=2;
    int y=0;
        }


  public class UseStatic{
     public static void main(String args[]){

       System.out.println("利用类调用静态变量");
       System.out.println("x="+Point.x);

       //System.out.println("y="+Point.y);
       Point p1=new Point();
       System.out.println("利用对象调用");
       System.out.println("x="+p1.x);
       System.out.println("y="+p1.y);

       Point p2=new Point();
       p2.y=3;
       System.out.println("对象p1中y的值"+"y="+p1.y);
       System.out.println("对象p2中y的值"+"y="+p2.y);
       p1.x=6;
       System.out.println("对象p1中x的值"+"x="+p1.x);
       System.out.println("对象p2中x的值"+"x="+p2.x);

  }
}