Java面向对象练习题

1.
Java面向对象练习题_第1张图片

import java.util.Scanner;
class Demo5_2{
	/*
	类
		StopWatch
		属性 startTime  endTime
		无参构造函数   初始化startTime
		行为 start()  将startTime重设为当前时间
			 stop() 将endTime设为当前时间
			 getElapsedTime() 记录过去了多少时间
	*/
	public static void main(String[] args){
		StopWatch s=new StopWatch();
		long start=s.start();
		System.out.println(start);
		if(s.ifStop()){
			long end=s.stop();
			System.out.println(end);
			System.out.println(s.getElapsedTime(start,end));
		}
	}
}
class StopWatch{
	long startTime;
	long endTime;
	
	public StopWatch(){
		this.startTime=System.currentTimeMillis();
	}
	public long start(){
		this.startTime=System.currentTimeMillis();
		return startTime;
	}
	public long stop(){
		this.endTime=System.currentTimeMillis();
		return endTime;
	}
	public long getElapsedTime(long startTime,long endTime){
		return (endTime-startTime);
	}
	public boolean ifStop(){
		Scanner scanner=new Scanner(System.in);
		if (scanner.nextBoolean()){
			return true;
		}else{
			return false;
		}
	}
	public long getStartTime(){
		return this.startTime;
	}
	public long getEndTime(){
		return this.endTime;
	}
}

2.
Java面向对象练习题_第2张图片

import java.util.Scanner;
class Demo5_3{
	public static void main(String[] args){
		Fan f=new Fan();
		Scanner scanner=new Scanner(System.in);
		while(true){
			int i;
			boolean flag=false;
			System.out.println("请输入0(关)或1(开):");
			i=scanner.nextInt();
			if(i==1){
				flag=true;
				f.setOn(flag);
				System.out.println(f.toString(f.isOn()));
				break;
			}else if(i==0){
				System.out.println(f.toString(f.isOn()));
				break;
			}else {
				System.out.println("请重新输入:");
			}
		}
	}
}
class Fan{
	final static int SLOW=1;
	final static int MEDIUM=2;
	final static int FAST=3;
	private int speed=SLOW;
	private boolean on=false;
	private double radius=5;
	private String color="blue";
	public Fan(){
	
	}
	public void setSpeed(int speed){
		this.speed=speed;
	}
	public void setOn(boolean on){
		this.on=on;
	}
	public void setRadius(int radius){
		this.radius=radius;
	}
	public void setColor(String color){
		this.color=color;
	}
	public int getSpeed(){
		return this.speed;
	}
	public boolean isOn(){
		return this.on;
	}
	public double getRadius(){
		return this.radius;
	}
	public String getColor(){
		return this.color;
	}
	public String toString(boolean on){
		String s;
		if(on){
			s=this.speed+":"+this.color+":"+this.radius;
			return s;
		}else{
			s="Fan is off:"+this.color+":"+this.radius;
			return s;
		}
	}
}

3.
Java面向对象练习题_第3张图片

import java.util.Scanner;
class Demo5_4{
	public static void main(String[] args){
		Scanner scanner=new Scanner(System.in);
		System.out.print("请输入a,b,c:");
		QuadraticEquation q=new QuadraticEquation(scanner.nextDouble(),scanner.nextDouble(),scanner.nextDouble());
		if(q.getDiscriminant()>0){
			double x1=q.getRoot1(q.getDiscriminant());
			double x2=q.getRoot2(q.getDiscriminant());
			System.out.println("x1="+x1);
			System.out.println("x2="+x2);
		}else if(q.getDiscriminant()==0){
			double x=q.getRoot2(q.getDiscriminant());
			System.out.println("x="+x);
		}else{
			System.out.println("The equation has no roots.");
		}
	}
}
class QuadraticEquation{
	private double a;
	private double b;
	private double c;
	public QuadraticEquation(){
		this(0,0,0);
	}
	public QuadraticEquation(double a,double b,double c){
		this.a=a;
		this.b=b;
		this.c=c;
	}
	public double getA(){
		return this.a;
	}
	public double getB(){
		return this.b;
	}
	public double getC(){
		return this.c;
	}
	public double getDiscriminant(){
		double delt=Math.pow(getB(),2)-4*getA()*getC();
		return delt;
	}
	public double getRoot1(double delt){
		double x1=(-getB()+getDiscriminant())/(2*getA());
		return x1;
	}
	public double getRoot2(double delt){
		double x2=(-getB()-getDiscriminant())/(2*getA());
		return x2;
	}
}

4.
Java面向对象练习题_第4张图片

import java.util.Scanner;
class Demo5_5{
	public static void main(String[] args){
		Scanner scanner=new Scanner(System.in);
		System.out.print("Enter row-col:");
		double[][] arr=new double[scanner.nextInt()][scanner.nextInt()];
		System.out.println("请输入矩阵:");
		for(int i=0;il.maxValue){
					l.row=i;
					l.col=j;
					l.maxValue=a[i][j];
				}
			}
		}
		System.out.print("The location of the largest is "+l.maxValue+" at "+"("+l.row+","+l.col+")");
	}
}

5.
Java面向对象练习题_第5张图片

class Demo5_6{
	public static void main(String[] args){
	Circle c1=new Circle(2.0,2.0,5.5);
	Circle c2=new Circle();
	System.out.println(c1.getArea());
	System.out.println(c2.getArea());
	System.out.println(c1.getPerimeter());
	System.out.println(c1.contains (3,3));
	System.out.println(c1.contains(new Circle(4,5,10.5)));
	System.out.println(c1.overlaps(new Circle(3,5,2.3)));
	}
}
class Circle{
	private Pointer center;
	private double radius;
	public Circle(){
		this(0,0,1);
	}
	public Circle(double x,double y){
		this.center=new Pointer(x,y);
	}
	public Circle(double x,double y,double radius){
		center=new Pointer(x,y);
		this.radius=radius;
	}
	public double getArea(){
		return Math.PI*Math.pow(this.radius,2);
	}
	public double getPerimeter(){
		return Math.PI*2*this.radius;
	}
	public double getRadius(){
		return this.radius;
	}
	public boolean contains(double x,double y){
		Pointer c=new Pointer(x,y);
		double distance=center.getDistance(c);
		if(distance>this.radius){
			return false;
		}else{
			return true;
		}
	}
	public boolean contains(Circle other){
		double distance=center.getDistance(other.center);
		if(distance>Math.abs(this.radius-other.radius)){
			return false;
		}else{
			return true;
		}
	}
	public boolean overlaps(Circle other){
		double distance=center.getDistance(other.center);
		if(distance(this.radius-other.radius)){
			return false;
		}else{
			return true;
		}
	}
}
class Pointer{
	private double x;
	private double y;
	public Pointer(){
		this(0,0);
	}
	public Pointer(double x,double y){
		this.x=x;
		this.y=y;
	}
	public double getDistance(Pointer c){
		double deltX=this.x-c.x;
		double deltY=this.y-c.y;
		return Math.sqrt(Math.pow(deltX,2)+Math.pow(deltY,2));
	}
	public double getX(){
		return this.x;
	}
	public double getY(){
		return this.y;
	}
}

6.
Java面向对象练习题_第6张图片

class Demo5_7{
	public static void main(String[] args){
		MyDate md=new MyDate();
		System.out.println(md.getYear());
		System.out.println(md.getMonth());
		System.out.println(md.getDay());
		
	}
}
class MyDate{
	private long year;
	private long month;
	private long day;
	private long days;
	private static int[] daysOfYear;
	private static int[] runYears={31,29,31,30,31,30,31,31,30,31,30,31};
	private static int[] pingYears={31,28,31,30,31,30,31,31,30,31,30,31};
	//静态代码块 类加载完毕后直接执行
	static{
		daysOfYear=new int[50];//1970-1971...
		for(int i=1970;i

7.
Java面向对象练习题_第7张图片

class Demo5_8{
	public static void main(String[] args){
		RegularPolygon r=new RegularPolygon(6,4);
		RegularPolygon r1=new RegularPolygon(10,4,5.6,7.8);
		RegularPolygon r2=new RegularPolygon();
		System.out.println(r.getPerimeter());
		System.out.println(r.getArea());
		System.out.println(r1.getPerimeter());
		System.out.println(r1.getArea());
		System.out.println(r2.getPerimeter());
		System.out.println(r2.getArea());
	}
}
class RegularPolygon{
	private int n;
	private double side;
	private Pointer center;
	public RegularPolygon(){
		this(3,1,0,0);
	}
	public RegularPolygon(int n,double side){
		this(n,side,0,0);
	}
	public RegularPolygon(int n,double side,double x,double y){
		this.n=n;
		this.side=side;
		this.center=new Pointer(x,y);
	}
	public int getN(){
		return this.n;
	}
	public double getSide(){
		return this.side;
	}
	public Pointer getCenter(){
		return this.center;
	}
	public double getPerimeter(){
		return this.n*this.side;
	}
	public double getArea(){
		return (this.n*Math.pow(this.side,2))/(4*Math.tan(Math.PI/this.n));
	}
}
class Pointer{
	private double x;
	private double y;
	public Pointer(){
		this(0,0);
	}
	public Pointer(double x,double y){
		this.x=x;
		this.y=y;
	}
	public double getX(){
		return this.x;
	}
	public double getY(){
		return this.y;
	}
}

8.Arrays工具类

class ArraysDemo{
	public static void main(String[] args){
		int[] arr=new int[]{5,6,2,3,4,1,8,9,7};
		System.out.println(MyArrays.toString(arr));
		MyArrays.sort(arr);
		System.out.println(MyArrays.toString(arr));
		System.out.println(MyArrays.binarySearch(arr,4));
		System.out.println(MyArrays.binarySeachUpper(arr,4));
		//System.out.println(MyArrays.toString(arr));
	}
}
class MyArrays{
	public static void sort(int[] a){
		if(a==null){
			System.out.println("数组为空");
			return;
		}
		if(a.length==0){
			System.out.println("数组中没有元素");
			return;
		}
		for(int i=1;i0&&a[j-1]>e;j--){
				a[j]=a[j-1];
			}
			a[j]=e;
		}
	}
	public static int binarySearch(int[] a,int key){
		if(a==null){
			System.out.println("数组为空");
			return -1;
		}
		if(a.length==0){
			System.out.println("数组中没有元素");
			return -1;
		}
		if(isSort(a)){
			int min=0;
			int max=a.length-1;
			int mid=(min+max)/2;
			while(a[mid]!=key){
				if(a[mid]>key){
					max=mid-1;
				}else if(a[mid]max){
					System.out.println("找不到");
					return -1;
				}
			}
			return mid;
		}
		System.out.println("找不到");
		return -1;
	}
	private static boolean isSort(int[] a){
		for(int i=0;ia[i+1]){
				return false;
			}
		}
		return true;
	}
	public static int[] copy(int[] a,int newLength){
		int[] b=new int[newLength];
		for(int i=0;i0&&b[j-1]>e;j--){
				b[j]=b[j-1];
				indexs[j]=indexs[j-1];
			}
			b[j]=e;
			indexs[j]=index;
		}
		int index=binarySearch(b,key);
		return b[index];
	}
	public static String toString(int[] a){
		if(a.length==0){
			return "["+"]";
		}
		String s="[";
		for(int i=0;i

9.吃鸡

import java.util.Arrays;
class ChiJi{
	public static void main(String[] args){
		Player p1=new Player("小明");
		Player p2=new Player("老王");
		Clips clips=new Clips();
		for(int i=1;i<=20;i++){
			p1.zhuangDan(clips,new Bullent());
		}
		Gun gun=new Gun();
		p1.takeGun(gun);
		p1.shangTang(clips);
		for(int i=1;i<=30;i++){
			p1.kaiQiang(p2);
			if(p2.HP<=0){
				break;
			}
		}
		System.out.println("死亡");
		System.out.println(p2.HP);
	}
}
/*
类	玩家 Player
	属性 昵称 name
		 血量 HP
		 枪 gun
	行为 捡枪(枪)
		 装弹(弹夹,子弹)
		 上膛(弹夹)
		 开枪(玩家)
		 掉血(伤害值)
*/
class Player{
	String name;
	int HP;
	Gun gun;
	public Player(String name){
		this.name=name;
		this.HP=100;
		this.gun=null;		
	}
	public void takeGun(Gun gun){
		this.gun=gun;
	}
	public void zhuangDan(Clips clips,Bullent bullent){
		clips.loding(bullent);
	}
	public void shangTang(Clips clips){
		gun.takeClips(clips);
	}
	public void kaiQiang(Player enemy){
		gun.shoot(enemy);
	}
	public void diaoXue(int damage){
			HP-=damage;
	}
}
/*
类	枪
	属性 弹夹 clips
	行为 装弹夹=Player上膛(弹夹)
		 开枪(玩家)
*/
class Gun{
	Clips clips;
	public void takeClips(Clips clips){
		this.clips=clips;
	}
	public void shoot(Player enemy){
		Bullent bullent=clips.out();
		if(bullent==null){
			System.out.println("放了 一个空枪");
		}else{
			bullent.hit(enemy);
		}
	}

}
/*
类  弹夹
	属性 子弹 bullent
	行为 装弹(子弹)
		 出弹()
*/
class Clips{
	Bullent[] bullents=new Bullent[0];
	int maxSize=30;
	public void loding(Bullent bullent){
		if(bullents.length>=maxSize){
			System.out.println("弹夹已满");
		}else{
			bullents=Arrays.copyOf(bullents,bullents.length+1);
			bullents[bullents.length-1]=bullent;
		}
	}
	public Bullent out(){
		Bullent bullent;
		if(bullents.length>0){
			bullent=bullents[bullents.length-1]; 
			bullents=Arrays.copyOf(bullents,bullents.length-1);	
			return bullent;
		}else{
			System.out.println("没有子弹了!!!");
			return null;
		}
	}

}
/*
类	子弹
	属性 伤害值 damage
	行为 
		命中 hit(玩家)
*/
class Bullent{
	int damage=10;
	public void hit(Player enemy){
		enemy.diaoXue(damage);
	}
}

10.接口

class InterfaceDemo{
	public  static void main(String[] args){
		Button bt_login=new Button();
		//局部内部类(匿名实现子类的匿名对象)
		bt_login.doSomething(new Task(){
			public void doWhat(){
				System.out.println("登录....");
			}
		});
	}
}
class Button{
	public void  doSomething(Task task){
		task.doWhat();
	}
}
interface Task{
	public abstract void doWhat();
}

**11.内部类 **

class InsideDemo{
	public static void  main(String[] args){
		A a=new A();
		A.B b=a.new B();
		b.show();
		System.out.println(a.num);
		System.out.println(b.num);
	}
}
class  A{
	int num=1;
	class B{
		int num=2;
		public void show(){
			System.out.println("B ......");
			System.out.println(A.this.num);
		}
	}
}

12.抽象类

class AbstractDemo{
	public static  void main(String[] args){
		Animal a=new Dog();
		a.eat();
		Animal b=new Cat();
		b.eat();
	}
}
abstract class Animal{
	public abstract void eat();
}
class Dog extends Animal{
	public void eat(){
		System.out.println("狗吃骨头");
	}
}
class Cat extends Animal{
	public void eat(){
		System.out.println("猫吃鱼");
	}
}

13.代理模式

class DaiLiDemo{
	public static void main(String[] args){
		Wang w=new Wang();
		w.setP("Ma");
		w.happy();
	}
}
interface BadWoman{
	void happy();
}
class  Wang implements BadWoman{
	BadWoman b;
	public void setP(String name){
		if(name.equals("Ma")){
			b=new Ma();
		}else if(name.equals("Pan")){
			b=new Pan();
		}
	}
	public void happy(){
		b.happy();
	}
}
class Ma implements BadWoman{
	public void happy(){
		System.out.println("Ma happy!");
	}
}
class Pan implements BadWoman{
	public void happy(){
		System.out.println("Pan happy!");
	}
}

14.单例模式

class DanLiDemo{
	public static void main(String[] args){
		A a=A.setA();
		A b=A.setA();
		System.out.println(a==b);
		B b1=B.setB();
		B b2=B.setB();
		System.out.println(b1==b2);
	}
}
//饿汉模式
class A{
	public static A a=new A();
	public static A setA(){
		return a;
	}
}
//饱汉模式
class  B{
	public static B b=null;
	public static B setB(){
		if(b==null){
			b=new B();
		}
		return b;
	}
}

15.静态内部类

class StaticInsideDemo{
	public static void  main(String[] args){
		A a=new A();
		System.out.println(a.num);
		System.out.println(A.B.num);
		new A.B().show();
	}
}
class  A{
	int num=1;
	static class B{
		static int num=2;
		public void show(){
			System.out.println("B......");
		}
	}
}

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